Total Synthesis of the Big Four Antibiotics and Related Antibiotics

Home , Apramycin, Carbomycin, Josamycin, Oleandomycin, Tetracycline antibiotics, Thienamycin

REVIEW ARTICLE

Total synthesis of the big four antibiotics and related antibiotics

Kuniaki Tatsuta

The ﬁrst total syntheses of a variety of antibiotics have been accomplished by using carbohydrates as a chiral source. The key target molecules were members of the ‘Big Four’ classes of antibiotics (macrolides, aminoglycosides, b-lactams and tetracyclines), naphthoquinone antibiotics and their related antibiotics. The Journal of Antibiotics (2013) 66, 107–129; doi:10.1038/ja.2012.126

Keywords: antibiotics; carbohydrates; enantiospeciﬁc synthesis; natural products; total synthesis

INTRODUCTION In the present paper, the author introduces the dynamic as well as ‘Antibiotic’ was one of the greatest scientific discoveries in the 20th elegant parts of his total synthesis of big four antibiotics and related century and the masterpiece of the total synthesis of antibiotics and compounds, focusing not only on ‘art’ but also on the significance bioactive natural products is a display of beauty, achieving a status of of the total syntheses, and featuring his concept of ‘all begins from ‘art’ in organic chemistry. total synthesis’. Anybody can draw a picture, but pictures painted by famous painters such as van Gogh, Monet and Picasso are praised as ‘art’. At TOTAL SYNTHESIS OF MACROLIDE ANTIBIOTICS AND THE the present time, many chemists are able to synthesize natural RELATED MACROLACTONE ANTIBIOTICS products, even those having complicated structure, using advanced When a stone is thrown into a pond, several ripples are produced in organic chemistry. However, not all such synthesis is above the succession, gradually radiating outward from the point of entry until mundane and can thus be raised to the level of ‘art’. The author is of they finally cover the whole pond. The ‘stone’ in macrolide synthesis the opinion that ‘art’ is a sublimate of originality, and has inherent was the news that R B Woodward had begun the total synthesis of special characteristics, and, even in the 21st century, it should be erythromycin A (2) in 1973. His group including the author recognized as such. accomplished the total synthesis in 1981. Some ripples from this Among bioactive natural products, several antibiotics, termed as the point of origin are represented by Masamune’s methymycin synthesis ‘BigFour’,weretheforemostsubjectofresearchatthetimetheauthor in 1977, Corey’s erythronolide synthesis in 1978 and our syntheses of 1 1–6 started his study of antibiotic synthesis. As shown in Figure 1, they carbomycin B, leucomycin A3 (3) and tylosin (4) in 1977 and 1981. were the macrolides (oleandomycin (1), erythromycin A (2), leucomycin A3 (3), tylosin (4)), aminoglycosides (kanamycin A (5), The first total synthesis of 16-membered macrolide antibiotics apramycin (6)), b-lactams (thienamycin (7)) and tetracyclines (tetra- The first total syntheses of the 16-membered macrolide anti- 7 8,9 cycline (8)). The author’s group has fortunately succeeded in complet- biotics, A26771B (1980), carbomycin B (1980), leucomycin A3 ing the total syntheses of 102 diverse bioactive natural products, (josamycin, 1980),8,9 and tylosin (1982)10,11 were accomplished in our including the above-mentioned representatives of the big four anti- laboratories.1–6 These syntheses were based on the stereoselective biotics, and 95 of them represented the first total synthesis of the construction of the carbon skeletons from D-glucose as shown in respective compounds.2–6 It is noteworthy that most of optically active Figure 2. compounds have been synthesized efficiently using carbohydrates as The first total synthesis of tylosin (4) was accomplished by chiral sources, to help determine the absolute structure and to clarify coupling of the C1-C10 (13) and C11-C15 (14) segments derived their structure-activity relationships. The methodologies devised are from D-glucose, and the stereo- and regio-selective introduction of now established as the usual way in the natural product synthesis.2–6 the three sugar moieties (17, 19 and 22) (Figure 3).10,11 The The first total synthesis requires the creation of original synthesis C-methyl compound 9, derived from D-glucose, was converted into concepts and methodologies, including the definition of the absolute the unsaturated ester 10, which was transformed to the methyl structure of the bioactive natural products, as well as the verification ketone 13 through a Michael addition with lithiated methyl of their biological activities. methylthiomethyl sulfoxide to give the branched ester 12. This

Research Institute for Science and Engineering, Waseda University, Tokyo, Japan Correspondence: Professor K Tatsuta, Research Institute for Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan. E-mail: [email protected] Received 5 October 2012; revised 15 October 2012; accepted 24 October 2012 Total synthesis of big four antibiotics and related antibiotics K Tatsuta 108

O O O NH Me Me Me 2 HO O HO Me Me Me Me OH Me HO NH OH OH HO 2 N Me Me N Me Me Me OH O HO HO HO NH2 Me O O O Me O O O Me HO O Me H2N O O O O OMe HO O Me Me OMe Me Kanamycin A (5) O OH O OH OH Me Me O Me Oleandomycin (1) Erythromycin A (2) H2N OH HO HN HO OH O O Me O CHO NH H N 2 Me 2 O HO NH N Me 2 MeO HO HO O O O O OH Me Apramycin (6) Me Me O OAc Aminoglycoside Antibiotics O O Me Me Leucomycin A3 (3) O Me

O Me Me Me CHO HO Me OH N H H H H Me Me OH Me N Me Me NH2 O Me HO S HO O O O O O OH N O Me O OMe Me OH OMe O OH CO2H OH O OH O NH O OH 2 Me Tylosin (4) Me Thienamycin (7) Tetracycline (8)

Macrolide Antibiotics -Lactam Antibiotic Tetracycline Antibiotic

Figure 1 Representatives of big four antibiotics.

1 O C O C O C HO 6 HO AcO AcO HO HO OMe OMe 4 Me OH Sug O Sug O Sug O O HO Me 6 OH 1 CHO 9 CHO O OHC OHC OHC Me 12 Me OH OH Me Me Me Me N Me O Me HO 1 O HO O 9 HO HO O O 4 O O MeO OH OH OMe Me 1 CHO OMe O 1 OH D-Glucose O OH Me Me OH Me 12 HO O Sug 4: Tylosin OH OH O O 15 O 6 OH Me Me Me

Carbomycin Leucomycin A3 Tylosin

Figure 2 Total synthesis of 16-membered macrolide antibiotics from D-glucose.

addition of the lithiated reagent to the correct position from the aldehyde group. The ethylene acetal 16 was submitted to initial desired side was effectively assisted by the metal chelation between glycosylation with D-mycaminosyl bromide 17, yielding the the isopropylidene oxygen and the carboxyl oxygen of the transition b-glycoside 18 after methanolysis. The second glycosylation, state 11, to give only the natural conﬁguration at C6, as expected. accomplished by our particular method,8,13 using the glycal of This step was the ﬁrst key component in completion of the synthesis. mycarose 19 and 1,3-dibromo-5,5-dimethylhydantoin, to give the The aldehyde 14 was also derived from D-glucose through the 2-bromo-2-deoxy-a-glycoside 20 followed by deprotection and branched alcohol. Aldol condensation of 13 with 14 gave the debromination to afford de-mycinosyl tylosin (21). This product unsaturated keto-ester 15, which was transformed to the seco-acid, was also isolated from the natural sources.14 The third glycosylation, followed by lactonization according to Corey’s procedure12 to give a using the mycinosyl bromide 22 under Koenigs ÀKnorr conditions, tylonolide derivative 16, following formation of the acetal of the followed by deprotection, completed the total synthesis of tylosin (4).

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 109

The first total synthesis of 14-membered macrolide antibiotics then cyclization by intramolecular Horner ÀEmmons reaction after The author’s group accomplished the first total synthesis of a esterification of the C1-C7 and C8-C14 segments, 27 and 28,which 14-membered macrolide antibiotic, oleandomycin (1)(Figure4).15,16 were derived from the enantiomeric intermediates 25 and 26.Thesugar As mentioned above, this is also based on the construction of the moieties 30 and 31 were regio- and stereoselectively introduced on the skeleton from carbohydrates, L-andD-rhamnosides, (23)and(24), and aglycone, oleandolide (29), to give oleandomycin (1).

CO Me O 2 H H OH OBn Me H MeS CO Me O BnO OMe 2 O 5 OH OH Me O MeS Me OH O O OOLi O 1 Me Me Me HO 3 C O OH BnO O MeS S S OH 2 Me H Me D-Glucose 9 MeS BnO O n-BuLi 10 11 12

O O O Me 10 Me 10 MeO Me Me O 10 Me OH 11 Me 615 6 OMe + Me OMe 6 Me Me Me O O TrO H TrO O Tr O O OH 15 3 3 11 15 3 MeO 1 OH O OH OH O OH Me CO2Me 13 14 1 Me 15 16

O O Me O O N Br Me Me Me N CHO O Br O Me Me Me Me N Me N Me Me HO Me HO Me Tr O O O OH AcO O OH O Me HO 14 O O O Me O O β Me 3 α NMe OH Me 2 O OH O OH OH Br O AcO 17 Me Me 19 Me Me AcO X (Mycarose 20: X = Br (Mycaminose 18 21: X = H Moiety) Moiety) O Me CHO Me Me Me N Me O β Me HO Me HO O O O O O OH O Me OMe Me Br OMe O OH OH O AcO 22 Me Me MeO OMe (Mycinose 4: Tylosin Moiety)

Figure 3 Total synthesis of tylosin.

1 CO2H Me HO O OMe O OMe BnO 3 Me Me OH Me Me N O 5 O S CbzO O Me BnO O O NMe N Me Me OH OH Me Me O 2 Me 9 OMe Me Me Me 23 25 OAc OH Me Me 30 31 N Me 27 OH Me HO Me Me O Me CSA, MS 4A O O PO(OMe)2 Me O OH 1 CH Cl Me 8 2 2 O O Me OH O OH Me O Me OMe O 10 Me Me Me O OH OHHO BnO Me OMe HO OMe Me 29 1: Oleandomycin OH Me 13 24 26 OH 28

Figure 4 Total synthesis of oleandomycin.

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 110

The total synthesis of erythromycin A (2) was also accomplished in The relative stereochemistry was elucidated and detected a our laboratories via an original stereo- and regioselective introduction 5-6-10-6-membered tetracyclic core (Figure 7). We accomplished of sugar moieties to the aglycone 32 (Figure 5).17 The glycosylation to the first total synthesis of cochleamycin A, which facilitated the C3 hydroxyl group of 29 and erythronolide derivative 33 determination of the absolute structure, by using intramolecular predictively posed an extremely difficult problem, due to the low Diels ÀAlder reaction followed by direct construction of the reactivity connected with the sterically crowded nature of the C3 10-membered rings,26 which was well-known to be difficult. After hydroxyl group and the formation of a hydrogen bond between its our first total synthesis, Roush’s group reported another synthesis hydroxyl group and C1 carbonyl group. However, our glycosylation, route.27 using the 2,6-anhydro-2-thio sugar 34 worked very efficiently to For maximum convergency, the acyclic precursor 52 of the give the desired a-glycoside 35 in 92% yield. This was converted Diels ÀAlder reaction was constructed by connection of two chiral to erythromycin A (2) through desulfurization to give the 2,6- segments, 48 and 50, which were prepared from a small carbohydrate dideoxyglycoside. 47 and (S)-1,2,4-trihydroxybutane (49), respectively, by our pre- We also developed several other glycosylation methods to synthe- viously developed methodologies.28 Coupling of 48 and 50 size many natural products.18,19 proceeded smoothly to give the alcohol 51 in quantitative yield. This was selectively reduced to the cis, trans-diene structure, Total synthesis of the macrolactone antibiotic, tubelactomicin A which was crucial to the construction of the desired 5–6-membered Tubelactomicin A (46) was isolated from the culture broth of ring by intramolecular Diels ÀAlder reaction. Oxidation of the a b Nocardia sp. MK703-102F1 and showed strong and specific anti- allylic alcohol gave the , -unsaturated aldehyde 52, which was microbial activities against drug-resistant Mycobacterium sp.20 Its submitted to intramolecular Diels ÀAlder reaction in the presence 1 structure was determined by X-ray crystallographic analysis to be of Yb(fod)3 at 140 C. The desired adduct 53 was obtained as a single the 16-membered lactone fused with a trans-decalin skeleton. product in good yield. This intramolecular Diels ÀAlder reaction 21 produced four critical stereocenters, as expected. The desired cycliza- Our total synthesis was completed from L-arabinose, although, independently, another successful synthesis was reported.22 tion of the bromo-aldehyde 54 was accomplished with SmI2 to give The stereochemical array of the northern part of the compound the 10-6-5-membered tricyclic product 55 as a single product, comprising the fully elaborated structure ready for conversion to was derived from L-arabinose (36) (Figure 6). After stereoselective the cochleamycin (58). Lactonization of the seco-acid 56 was realized introduction of C-methyl group, the lactone 37 was submitted to 29 reductive ring-opening to give the diol 38,possessingfunctionalityto under Kita’s conditions to afford the 10-membered lactone d be the northern part 39. The decalin moiety 43, the southern part of concomitant with the formation of the -lactone ring. The allylic alcohol of the lactone 57 was oxidized to a,b-unsaturated ketone by tubelactomicin A, was constructed by intramolecular Diels ÀAlder reaction. Citronerol (40) was converted to the triene 41.The exposure to MnO2, followed by selective acetylation with AcONa and Ac Oat601C to afford ( )-cochleamycin A (58). The synthetic 58 stereoselective Diels ÀAlder reaction to construct the additional four 2 þ chiral centers was realized by heating 41 in xylene, which gave the was identical in all respects, including the optical rotation, with natural cochleamycin A, completing the first total synthesis to adduct 42 as a single product. This was converted to 43 to couple with the northern part 39. establish the absolute structure. Treatment of the mixture of 39 and 43 under the conditions of Thus, the simplest carbohydrate 47 was efficiently used for the total Suzuki coupling gave the tetraene seco-acid 44 after desilylation.23 synthesis. In addition, the first total synthesis of another tetracyclic antibiotic having a unique g-lactone, tetrodecamycin (59), was also The seco-acid 44 was submitted to the macrolactonization by the 30 Shiina method24 to construct the lactone 45. Deprotection and accomplished by using 47 in our laboratories. selective oxidation afforded ( þ )-tubelactomicin A (46). TOTAL SYNTHESIS OF AMINOGLYCOSIDE ANTIBIOTICS The first total synthesis and determination of the absolute The author’s synthetic studies on antibiotics began with the determi- structure of ( þ )-cochleamycin A, which exhibits a unique nation of the absolute structure and the total synthesis of kanamycins 10-membered lactone A(5), B and C (Figure 1).31,32 Subsequently, in 1982, the author had ( þ )-Cochleamycin A (58) was isolated by the Kirin Brewery another chance to undertake work on the total synthesis of group from a cultured broth of Streptomyces sp. and showed aminoglycoside antibiotics, namely, apramycin (6)andsaccharocin cytotoxicity against P388 leukemia cells and antimicrobial activities.25 (69) (Figure 8).

SPh OMe O O Bn O OH Me Me Me O O Me Me 9 Me Me S Me 9 Me Me Me HO OH Me Me HO OH Me O HO OH OH HO Me O 34 O Me N Me OH OH Me Me N Me Me HO Me O Me MeO O Me Me N Me O 1) aq. AcOH O O Me O OH Me NIS, TfOH O O Me 1 MeO 2) H Me 1 O O O Me MS 4A Me 2 O O OMe Me O O OMe Raney Ni O OH Me CH2Cl2 BnO Me O OH Me Me Me 92% Me O OH Me O Me 32 33 S 35 2: Erythromycin A

Figure 5 Total synthesis of erythromycin A.

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 111

OMPM OMPM HO MOMO O O MOMO LiAlH4 MOMO OH O OH Me HO MPMO THF Me 0 °C Me OH Me OH OH 36: L-Arabinose 37 38 B(OH)2 39 CO Et CO SE Me Me 2 2 EtO C H H TB SO 2 TBSO I Me BHT Me Me HO Me Me Me xylene Me Me Me Me ° H H O 130 C O OH 40 41 42 43 OMPM NO2O O NO2 1) Pd (dba) O OMPM CO SE 2 3 MOMO 2 TlOEt H MeMe MOMO I Ph3As Me aq.THF DMAP Me Me Me + OH Me Me Me 2) TBAF CO H CH2Cl2 H 2 OH OH THF H B(OH)2 39 43 Me Me Me H OH 44 OMPM CO2H MOMO HO

Me Me Me Me O O O O H H

Me Me Me Me Me Me H H OH OH 45 46: (+)-Tubelactomicin A

Figure 6 Total synthesis of ( þ )-tubelactomicin A.

The first total synthesis of apramycin and saccharocin was N-benzyloxy-carbonylated to 67. In the glycosylation studies on Apramycin (6)andsaccharocin(69) are antibiotics active against 67, the best result was realized under modified Mukaiyama condi- 36 gram-positive and gram-negative bacteria, including strains resistant tions using 4-azido-2,3,6-tri-O-benzyl-4-deoxy-b-D-glucopyranosyl to other aminoglycoside antibiotics. Structurally, 6 and 69 contain the fluoride (68) to give the glycoside, subsequently deprotected by unusual bicyclic amino-octodialdose and, in addition, 4-amino-4- hydrogenolysis to furnish apramycin. 33,34 deoxy-D-glucose and D-glucose units, respectively. The first total Similarly, saccharocin was synthesized by glycosylation of 67 with synthesis of apramycin and saccharocin was accomplished in our 2,3,4,6-tetra-O-benzyl-b-D-glucopyranosyl fluoride. laboratories in 1983.35 Our starting point was the known aminoglycoside antibiotic, neamine (60), which had already been TOTAL SYNTHESIS AND DEVELOPMENTS OF b-LACTAM synthesized by us. Neamine was converted into the aldehyde 61 by ANTIBIOTICS effective oxidation of the primary amino group (Figure 8). The The molecular architecture associated with the b-lactam antibiotics aldehyde 61 was converted by our carbon-elongation method to the has posed some of the greatest challenges in synthetic chemistry, and acetyl glycal 62. This was submitted to azidonitration using sodium this family has provided the stimulus for development of novel azide and ammonium ceric nitrate to give azidoglycosyl nitrate 63. methodologies for construction of their skeletons and side chains The C3 position of the dimesylate 64 was selectively chlorinated to (Figure 9). Among the cephem antibiotics, the fourth generation has form the 30-chloro compound, which was dechlorinated with been especially noteworthy (Figure 10). tributylstannane to give the 30-deoxy compound 65.Epimerization of the 60-hydroxy group, by heating 65 with sodium acetate trihydrate, Total synthesis of the b-lactam antibiotic, ( þ )-thienamycin yielded the cis cyclic carbamate 66 needed for the apramycin skeleton. Thienamycin (7) was discovered in fermentation broths of Removal of all protecting groups gave aprosamine (67:Z¼ H), which Streptomyces cattleya and showed exceptional antibacterial potency

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 112

TrO HO Me O OH MOMO OMOM O OH I OMOM HO TBDPSO

47 48 49 50

PdCl2(PPh3)2 1) Zn, BrCH2CH2Br HO Me HO Me CuI LiCuBr2 Et NH EtOH-THF MOMO OMOM 2 MOMO OMOM I + OMOM OMOM PhMe 2) IBX TBDPSO TBDPSO PhMe-DMSO 50 48 51

Me Me Yb(fod)3 OHC 2,6-di-tert-butyl-p-cresol H OHC H OR TBDPSO RO RO OMOM xylene H MOMO OMOM 140 °C TBDPSO H R = MOM 52 53 Me Me Me EtO2C Br H OH H OH H 1) ethyl ethynyl ether H H OR SmI2 OR H OH [RuCl (p-cymene)] RO RO 2 2 H 10 H H DMF THF CO2Et CO H OHC RO HO 2 H 0 °C H H 2) CSA/ THF R = MOM OR OH R = MOM 54 55 56 Me Me O O OH H O H Me H H H OH OAc Me 1) MnO / EtOAc O 10 H 2 H H O H O O H 2) AcONa O H O HO Ac2O OH OH 60 °C OH 57 58: Cochleamycin A 59: Tetrodecamycin

Figure 7 Total synthesis of cochleamycin A and tetrodecamycin.

and spectrum.37 ( þ )-4-Acetoxy-3-hydroxyethyl-2-azetidinone (80) 75 to the lactone 76 was the key step of our strategy, although the has been well-known as a highly versatile intermediate for the lactone could not be obtained under usual oxidation conditions. We synthesis of carbapenem antibiotics, such as thienamycin finally discovered that, on exposure to Ag2CO3/Celite in benzene, 75 (Figure 9).38 The synthesis of 80 was initiated by the Sankyo was smoothly oxidized to the g-lactone 76 despite the presence of the group, followed by the Merck group, and culminated in the amino group. practical preparation by two Japanese companies, using The next important operation in the synthesis was to epimerize Noyori ÀMurahashi’s asymmetric procedures and chem-enzymatic stereoselectively and simultaneously the configurations at the C2 and procedures, respectively.38 The first stereocontrolled synthesis of C3 positions of 76. The best result was realized by using DBU in ( þ )-thienamycin (7) was reported by the Merck group, and the MeOH to afford predominantly the desired amino ester 77.This transformation of 80 to 7 was also made more attractive by a second result indicated that the C4 configuration of 76 controlled the Merck group. Consequently, the synthesis of the azetidinone 80 stereoselective construction of the C2 and C3 configurations of 77. 39,40 constitutes a formal total synthesis of ( þ )-thienamycin (7). Hydrolysis with 2 M NaOH led to the hydroxy acid 78, which was in We reported a novel enantiospecific synthesis of 80 from a turn submitted to the b-lactam formation. For our purpose, a carbohydrate through our developed skeletal rearrangement and Grignard-mediated cyclization of the silylated derivative seemed most stereoselective epimerization (Figure 9).41 Our starting material was promising. Thus, 78 was silylated with trimethylsilyl chloride and the commercially-available methyl 2-amino-2,6-dideoxy-a-D- gluco- hexamethyldisilazane, followed by treatment with tert-butylmagne- pyranoside (70), which has also been isolated from natural sources.41 sium chloride to give the bis-silylated b-lactam 79.Oxidative Reaction of 70 with o-benzenedisulfonyl dichloride gave the cyclic decarboxylation by Pb(OAc)4 gave exclusively the desired ( þ )-4- sulfonate 71, which was submitted to our skeletal rearrangement, acetoxy-3-hydroxyethyl-2-azetidinone (80), with removal of silyl including ring-contraction with potassium tert-butoxide. The groups. This was identical in all respects to the authentic sample. resulting 3-formyl-furanoside 72 was oxidized to the carboxylic acid Overall, the yield was B35% in 11 steps from 70. Key steps include 73 in 91% yield. Removal of the N-sulfonyl group of 73 by Birch our original skeletal rearrangement with ring-contraction, oxidation reduction produced the corresponding amino acid 74.Thiswas of the 2-aminofuranose, and stereoselective epimerization to the hydrolyzed and then esterified to give the furanose 75. Oxidation of desired configurations.

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 113

8' 6' O2NO N 6' CHO 3 NH O OAc OAc 2 O O O O O O O NHTs Ac O Ac O HO NHTs NaN3, CAN TsHN O TsHN TsHN NHTs HO NH O O 2 O NHTs Ac Ac H2N O N MeCN O N O O HO O Ts O Ts NH2 HO

60: Neamine 61 62 63 O Me Me NZ NZ O 6' 1) LiCl 6' Me N OMs OMs 6' Me O DMF MeO O O Me O O 100 °C, 2 h O AcONa•3H O O O MsO 3' NHTs 2 3' TsHN NHTs TsHN 3' O O NHTs 2) n-Bu SnH MeOCH2CH2OH TsHN O NHTs 3 O NHTs ° O AIBN 130 C, 2 d O NHTs O O 78% dioxane O 80 °C, 1.5 h

64 65 66 OBn O OH Me N3 OH BnO F O Me HO NZ BnO R OH 6' HO HN 8' 68 HO O O O O O 3' NHZ ZHN NH O H N 2 HO NHZ 2 O HO HO NH2 HO

67 (Aprosamine: Z = H) 6: Apramycin : R = NH2 69: Saccharocin : R = OH

Figure 8 Total synthesis of apramycin and saccharocin.

SO Cl Me Me Me 2 O O O Me CHO CO2H SO2Cl Me O t-BuOK OMe HOSO2NH2 OMe NaHCO3 O O pyridine THF NaClO2 MeOH CO H OH H O OMe HN HN 2 SO2 SO2 then OMe O S NH HO OMe 2 Li SO KO3S NaO3S NH2 NH2 2 liq. NH 70 3 74

71 72 73

Me Me Me O ® O O OH NH2 Ag2CO3-Celite DBU 2 M NaOH CO2Me OH 4 CO2Me O H2N O Me CO H 2 3 2 2 PhH 3 MeOH MeOH CO2Me NH2 NH2 CO2Me 75 76 77 78

1) TMSCl HO TMSO HO H H HMDS H H H H ° Pb(OAc)4 PhMe, 95 C CO2H OAc Me NH Me Me S 2 N N DMF-AcOH NH 2) t-BuMgCl O O TMS 70 °C O THF CO2H 79 80 7: Thienamycin

Figure 9 Total synthesis of thienamycin.

Practical preparation of (Z)-2-(5-amino-1,2,4-thiadiazol-3-yl)-2- thiadiazol-3-yl)-2-(alkoxyimino)acetic acid (Figure 10). The E-isomer methoxy- iminoacetic acid, a side-chain of the fourth generation of is known to be of little value for b-lactam antibiotic use. Conse- cephem antibiotics quently, it was our intention to successfully develop a novel general Recently, (Z)-7b-(2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(alkoxyimi- method of entry into the Z-isomer, even though several methods have no)acetamido)-cephalosporins, such as cefozopran (89), have been already been reported for the production of 88. reported as clinically useful antibiotics having excellent antimicrobial We devised a novel and concise preparation directed toward the activities.42 Their common acyl moiety at the C7 position mass production of the (Z)-methoxyimino compound: (Z)-2-(5- corresponds to the Z-isomer (for example, 88)of2-(5-amino-1,2,4- amino-1,2,4-thiadiazol-3-yl)-2-(methoxyimino)acetic acid (88) based

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 114

KSCN ClCO Me O H N 2 I2/ DMSO 2 ° H 70 C, 30 min MeOCOHN N N CO2Me conc. H2SO4 N N CO2Me N then OMe MeOCOHN EtOAc O OMe S N S MeOCOHN N 81/MeCN O S rt, 15 min 81 82 83 87

1) AcOOH aq. t-BuOH KSCN 2) HCl/MeOH H N ClCO2Me 2 ° H 70 C, 30 min MeOCOHN N N CHO N then MeOH MeOCOHN N S N S O 84/ MeCN O 35 °C rt, 15 min 84 85 86

OMe N 1) NH OMe•HCl OMe O 2 N 7 S 95% MeOH N CONH N N CO2Me CO2H H N N N N 2 S N 2) 1 M NaOH N O N+ MeOCOHN H2N - S S CO2 N 87 88 89: Cefozopran

Figure 10 Practical preparation of a side-chain of the fourth generation of cephem antibiotics.

on the skeletal rearrangement of the aminoisoxazoles 81 or 84, Before and during the challenge to the total synthesis of tetra- and stereoselective formation of 88 (Figure 10).43,44 3-Amino-5- cycline, we have been synthesizing naphthoquinone antibiotics to methoxyisoxazole (81) was subjected to the skeletal rearrangement in develop our own methodologies for the construction of the skeleton. question. A suspension of methyl chloroformate and potassium Namely, pyranonaphthoquinone antibiotics (90–95) were synthesized thiocyanate in acetonitrile was stirred at 70 1C for 30 min to give by unique strategies including Michael ÀDieckmann cyclization. After methoxycarbonyl isothiocyanate in situ, which in turn reacted with the tetracycline synthesis, the author completed the first total 81 to afford methyl 2-(5-methoxycarbonylamino-1,2,4-thiadiazol- synthesis of a furanonaphthoquinone antibiotic, lactonamycin 3-yl)acetate (83) in 86% yield, through skeletal rearrangement of (120), and a pseudo-dimer of tetracycline, hibarimicinone (150), the intermediary thiourea derivative 82. This reaction mechanism was which represented the culmination of synthetic strategies and reasonably supported by the isolation of the similar intermediate 85 methodologies on antibiotics by the author. from 3-aminoisoxazole (84). The compound 85 was also converted to 83 through 86. Oxidation of 83 gave the 2-oxoacetate 87 (with DMSO Total synthesis of naphthoquinone-related antibiotics using and I2 in the presence of catalytic amounts of H2SO4) in 83% yield. carbohydrates and novel strategies The moderate yield was ascribed to purification difficulties due to Pyranonaphthoquinone antibiotics (90–95) have been shown to their polar nature. Without isolation of the keto-ester 87, the methyl possess significant antimicrobial, antifungal and antitumor activities ester 83 was quantitatively converted into the desired Z-isomer of (Figure 11). Structurally, the stereo-alignment of nanaomycin D (91) 2-(methoxyimino)acetate. Saponification provided the target product is included in nanaomycin A (90)andBE-54238B(95), while that of 88 in quantitative yield. This was derived to cefozopran (89), which kalafungin (92)isinmedermycin(93) and BE-52440A (94). The was marketed in 1995.45 representative antibiotics are nanaomycin A (90)andD(91), which were isolated and developed by O¯ mura’s group.50,51 Moreover, a CHALLENGE TO THE TOTAL SYNTHESIS OF TETRACYCLINE furanonaphthoquinone antibiotic, lactonamycin (120), was found to ANTIBIOTICS AND RELATED ANTIBIOTICS have the hexacyclic system and the glycosidic bond at the tertiary For almost half a century, tetracycline (8) has been widely recognized alcohol. These unique structures have drawn attention both for their as a major antibiotic, due to both its unique structural features synthesis using new methodologies and for the creation of novel as well as antibacterial activities.46 The total synthesis of tetracycline biologically active compounds. The author’s group accomplished the families was initiated by Woodward’s 6-demethyl-6-deoxytetracycline first total syntheses of these antibiotics, and developed a synthetic synthesis in 1962, followed by Muxfeldt’s terramycin synthesis strategy for the stereoselective construction of densely-functionalized in 1968, culminating Stork’s 12a-deoxytetracycline synthesis in naphthoquinones using carbohydrates.2–6 1996.1,47 However, all these syntheses have been accomplished only in racemic forms. The total synthesis of natural ( À)-tetracycline (8) The first total synthesis of nanaomycin D and its enantiomer, remained an unanswered challenge, despite the remarkable kalafungin—the ‘enantiodivergent’ total synthesis.Carbohydrates achievements as described above. In 2000, the first total synthesis of have been used widely as chiral sources in stereospecific syntheses ( À)-tetracycline (8) was completed in our laboratories using of natural products, as mentioned above.1–6 Although various D-glucosamine as a chiral starting material, which allows stereo- carbohydrates are available, in most of them one enantiomer is specific construction of the densely and sensitively functionalized A abundant while another isomer is difficult to get in much quantity. ring (Figure 18).48 In 2005, Myers’ group presented the second Thus, it is hoped that both enantiomeric chiral synthons in the total synthesis of ( À)-tetracycline.49 synthesis are derived from only one abundant enantiomer of a

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 115

OH O Me OH O Me OH O Me

O O O

O O O O CO2H O O O 90: Nanaomycin A 91: Nanaomycin D 92: Kalafungin

OH O Me OH Me Me H HO O O O OH O Me OH O OMe N O Me2N O O S O MeO O O O O O O O OH Me OH Me O OH 93: Medermycin 94: BE-52440 A 95: BE-54238B

Figure 11 Representative pyranonaphthoquinone antibiotics. carbohydrate. During synthetic studies on nanaomycin D (91) and its biogenetically synthesized by epoxy-opening dimerization of OM-173 enantiomer, kalafungin (113), in our laboratories, a new methodology aE(111), which was isolated by the O¯ mura group.57 It was possible to was developed to enable synthesis of both enantiomers from a single obtain the antibiotic 111 by stereospecific epoxydation of enantiomeric carbohydrate, creating ‘enantiodivergent synthesis’.52–54 pyranonaphthoquinone 110, which could be derived from the The critical point of the methodology was catalytic isomerization of lactone 106 and g-hydroxyester 107 by our enantiodivergent stereocenters (Figure 12). On the protected hydroquinone 96,the strategy, as mentioned above.52–54 The key reaction sequence is a isomerization at the C3 position was carried out to obtain the lactone regioselective epoxy-opening dimerization of the tetra-substituted 111 97 by elimination-recyclization equilibrium under basic conditions. with Na2SbySN2 reaction of the intermediary tert-thiolate. Using the quinone 98, the isomerization at C1 and C4 positions was Firstly, both enatiomeric intermediates (( À)- and ( þ )-110) were realized to afford the lactone 99 by enolization Àprotonation equili- selectively synthesized from the key intermediates 106 and 107. brium under acidic conditions. This methodology was widely applied Subsequent epoxidation afforded ( þ )- and ( À)-OM-173 aE to the construction of pyranonaphthoquinone antibiotics. The (( þ )- and ( À)-111). The one epimer, ( þ )-111, was hydrolyzed to enantiodivergent synthesis of nanaomycin D (91) and kalafungin natural ( þ )-nanaomycin E (112),58 which was also isolated by 52–54 (92) based on this strategy is shown in Figure 13. O¯ mura’s group, while the other ( À)-111, on treatment with Na2S, Methyl L-rhamnoside (100) was converted into the 2,3-di-O- was converted to natural ( þ )-BE-52440A (94). Thus, their absolute carbonyl-4-O-tosyl derivative 101 in 80% overall yield in a one pot structures were determined. reaction, with trichloromethyl chloroformate and then tosyl chloride in pyridine (Figure 13). Treatment of 101 with zinc powder and The first total synthesis of BE-54238B—the iminoquinone isomerization. sodium iodide in reflux aqueous acetonitrile gave the unsaturated We achieved the enantioselective total synthesis of BE-54238B (95)to alcohol 102. This olefin formation was also developed in our confirm its absolute structure (Figure 15).59 The bromo precursor 113 laboratories. Oxidation of 102 with pyridinium chlorochromate was prepared as mentioned above for the synthesis of nanaomycin D afforded the stable a,b-unsaturated ketone 103.MichaelÀDieckmann (91). The 113 was lithiated to couple with the L-pyroglutamic acid condensation of 103 with 4-methoxy-3-(phenylsulfonyl)-1(3H)-iso- derivative 114 to obtain the ketone 115. After construction of the benzofuranone prepared by Hauser’s procedures gave naphthopyr- pyrrolidine 116, Wittig reaction gave the cis-lactone 117 and the anone 104, which was transformed to the lactol 105 in three steps. trans-hydroxyl ester, in 67% and 22% yields, respectively. The lactone The lactol 105 was submitted to Wittig reaction, which afforded the 117 was suitable for the synthesis of the natural product 95, while the cis-lactone 106 and the trans-hydroxyl ester 107. The lactone 106 was hydroxyester could also be transformed to 117 in high yield by oxidized to the quinone 108, which was subsequently de-O-methy- heating with KHCO3 and 18-crown-6 in dimethylformamide. Acidic lated to give nanaomycin D (91). The hydroxyl ester 107 was removal of two Boc groups in 117 was followed by oxidative de-O- converted to the quinone 109, which was subjected to the above- methylation to give the quinone 118. This was effectively cyclized to mentioned acidic isomerization to produce kalafungin (92), the the hexacyclic product 119 through proton-tautomerization. This was enantiomer of nanaomycin D (91). de-O-methylated by BCl3 to give the retautomerized compound 95, which was identical in all respects with natural BE-54238B. The first total synthesis of BE-52440A and nanaomycin E.(þ )-BE- 52440A (94) was reported as an antitumor agent, produced by a The first total synthesis of a furanonaphthoquinone antibiotic, lactona- Streptomyces strain, by the Banyu group in 2000.55 The structure was mycin. Lactonamycin (120, Figure 16) was isolated from a culture identified as a dimer of nanaomycin derivatives bridged with sulfur broth of Streptomyces rishiriensis MJ773-88K4 by Matsumoto et al.60 (Figure 14), although the relative configuration remained unknown. in 1996. Lactonamycin (120) showed potent antimicrobial activities The first total synthesis of 94 was accomplished by us to help against gram-positive bacteria including methicillin-resistant determine the absolute structure.56 We assumed that 94 would be Staphylococcus aureus and vancomycin-resistant Enterococcus as well

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 116

OMe OMe Me OMe OMe Me OMe OMe Me OMe OMe Me base O O OH O 3 3

OMe O OMe OH CO2Et OMe OH CO2Et OMe OH CO2Et O 96 97

OH O Me OH O Me OH O Me OH O Me OH OH Me OH O Me

H+ O O 1 O 1 O O O 3 3 4 4 O O OH O O O O OH CO2Et O OH CO2Et O OH CO2Et O O O 98 99

Figure 12 Enantiodivergent methodologies for synthesis of pyranonaphthoquinone skeletons.

OMe SO2Ph

O TsO OMe Cl COCOCl O OMe OH Me 3 O HO O OMe then Me Zn O OMe PCC O OMe Me TsCl NaI Me MS 4A Me t-BuOLi O pyridine O O aq. MeCN CH2Cl2 OMe OH OH OH O OH O 100 101 O 102 103 104 OH O Me OMe OMe Me OMe O Me 1 O O CANO AlCl 3 3

O O OMe O O O O OMe OMe Me 106 O 108 O 91: Nanaomycin D Ph P=CHCO Et O 3 2

OH OMe OMe Me OH O Me OH O Me OMe OH 105 1) CAN O O cat. H2SO4 1 O 3 3 4 2) AlCl3

OMe OH CO2Et O OH CO2Et O O 107 109 O 92: Kalafungin

Figure 13 Enantiodivergent total synthesis of nanaomycin D and its enantiomer, kalafungin.

as antitumor activities.60,61 The unique structure of 120 was the tri-substituted olefin of 128 provided the triol, which was determined by X-ray crystallography and degradation studies. By subjected to stereoselective reduction and protection to obtain the the remarkable structure and activities, many groups have been diol 129. After oxidation of the secondary alcohol of 129, the tertiary attracted and challenged to synthesize this compound,62,63 alcohol was protected as triethylsilyl ether to yield 130. Methyl nevertheless, the total synthesis has been unprecedented. propiolate was introduced in the stereospecific manner under the We accomplished the first total synthesis of lactonamycin (120) basic conditions to give the cis-tertiary diol 131. De-silylation and the through Michael ÀDieckmann type cyclization.64 The stereoselective conjugate addition of the resulting primary alcohol proceeded to glycosylation of the tertiary alcohol with the 2,3-deoxysugar is afford 132. Treatment of the ester 132 in methanol under the acidic challenging, and rhodinose derivative 123 wasusedasaresolving conditions to give the g-lactone, followed by oxidation to the 1,4- agent for racemic 121. diketone 121. Thioester 122 corresponding to the DEF segment was synthesized Rhodinose thioether derivative 123 was synthesized from from 4-bromo-3,5-dimethylphenol 124 (Figure 17). O-Methylation of L-rhamnal through Ferrier reaction and inversion of the configuration 124 and subsequent lithiation followed by methoxycarbonylation gave of the secondary alcohol by Mitsunobu reaction. the ester 125, which was taransformed to the bicyclic 126. After The racemic 121 was subjected to glycosylation with 123 in the exchange of O-Me to O-Bn group, the bromide was converted into presence of silver triflate18 to give a diastereomeric mixture of only the sulfone 122. a-glycosides under a strong anomeric effect (Figure 17). The mixture The synthesis of the ABC segment 121 started from mono-O- was separated by silica gel column chromatography to give the methyl-dihydroxybenzoic acid 127 (Figure 17). Reduction of methyl optically pure 133 in 42% (practically 84%). ester and the successive oxidation of the aromatic ring in the presence Michael ÀDieckmann type condensation2–6 of the enone 133 of ethylene glycol gave quinone mono-acetal 128. Dihydroxylation of with the thioester 122 gave the protected lactonamycin 134.

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 117

OMe OMe Me OH O Me OH O Me OH O Me

O O O KOH O O O

OMe O enantio- O CO2Me O CO2Me O CO2H 106 O divergent (–)-110 synthesis (+)-111: (+)-OM-173 E 112: (+)-Nanaomycin E OH O Me OH O O OMe OMe Me OH O Me OH O Me OMe O O O Na2S O O S O MeO OMe OH CO Et O CO Me O CO Me 2 2 2 O O 107 (+)-110 (–)-111: (–)-OM-173 E OH Me O OH 94: (+)-BE-52440A

Figure 14 Total synthesis of OM-173 E, nanaomycin E and BE-52440A.

H Me Me OBoc NBoc NHBoc H OBoc Br OMe OBn Me O O OMe OBn NBoc OBn Ph P=CHCO Et 114 OMe OH 3 2 OBoc OBn H O t-BuLi OH PhMe THF O reflux OMe OMe Me –78 °C O 67% OMe OMe Me 113 115 OMe OMe Me 116

Me Me Me Me H OBoc H OH H H OH O OH O NBoc O NH O 1) TFA MeOH N O BCl3 N O OMe O O O H H ° 2) CAN 60 C CH2Cl2 aq. CH3CN O O O 0 °C O OMe O Me O OH Me OMe OMe Me OMe O Me 117 118 119 95: BE-54238B

Figure 15 Enantiodivergent total synthesis of BE-54238B.

O Me O Me O HO N O O N O F O F A O A O MeO MeO EtS BCDE BC E O O Me O SPh OH OBn O HO OBn O O SO2Et Me O 121 122 123 OH 120: Lactonamycin

Figure 16 Retrosynthesis of lactonamycin.

Hydrogenolysis of 134 afforded lactonamycin (120), completing the was converted into the selenide 136.Treatmentof136 with borane total synthesis. followed by H2O2 oxidation stereoselectively gave the alcohol by simultaneous formation of a new olefin group, which was benzylated The first total synthesis of natural ( À)-tetracycline to the olefin 137. This was submitted to Ferrier reaction with HgCl2 Anhydrotetracycline (147) was our first target (Figure 18)48,65 as it to give the cyclohexanone 138.The[4þ 2] cycloaddition of the provides a viable synthetic relay from 147 to tetracycline (8) via cyclohexenone, which was derived from 138 by dehydration, with the a two-step hydration at the 5a, 6-position.47 A reliable 12a- butadiene 140 did not proceed because of the steric repulsion. hydroxylation is required for the synthesis of 147.Thestarting- Therefore, 138 was epimerized at C2 and dehydrated to the isomer point glucosaminide 135, which was prepared from D-glucosamine, 139.Thea-hydroxymethyl group was an important factor for

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 118

Me Me Me O Me O N O N 1) Me2SO4 / K2CO3 Br O O acetone MeO MeO EtS

Me OH 2) nBuLi / ClCO2Me Me OMe OMe OBn THF, -78 °C Br SO2Et 124 88% (2 steps) 125 126 122

1) OsO / NMO•H O OMe 4 2 1) LiBH / THF O O acetone O O 1) (COCl)2 / DMSO O O 4 HO O MeOH-THF 2) NaBH4 / MeOH Et3N / CH2Cl2 HO TESO MeO 2) ethylene glycol 3) TBSCl / imidazole 2) TESOTf / pyridine DMF 65% (2 steps) O OH PIFA / CH2Cl2 OH O TBSO OTBS TBSO OTBS 84% (2 steps) 50% (3 steps) 127 128 129 130

Me O SPh

O OBn 123 MeO C CO2Me O 2 O O O O O 2-cyclohexen-1-one HO HO NaHMDS / THF TBAF / THF 1) AcCl / MeOH AgOTf MeO2C MeO TESO O O 2) IBX / (CH Cl) MS-4A 93% HO 2 2 CH Cl 54% (3 steps) HO 2 2 TBSO OTBS OH O −40 °C to rt, 11 h 131 132 ( )-121

Me (Resolution) O N O O O Me O Me EtS O O HO N O HO N O O O OBn O O MeO MeO MeO SO Et H2 / Pd-black O 2 122 O O OBn THF OH O O O O KHMDS / THF O 47% O Me O 42% Me O Me O

OBn OBn OH 133 134 120: Lactonamycin

Figure 17 Total synthesis of lactonamycin.

stereospecific introduction of the hydroxy group at C12a to give a and the perhydroxide 149 into ( À)-tetracycline (8), which was furan derivative 145. The cycloaddition with 140 in the presence of identical with natural ( À)-tetracycline in all respects, thus 2,6-di-tert-butyl-4-methylphenol proceeded from the b-face of 139, completing the first total synthesis. Our tetracycline synthesis was regio- and stereoselectively as expected. This highly-stereoselective the first to be accomplished, some 50 years after its structure had been reaction gave a labile adduct, which upon acidic oxidation, was determined.48 transformed to the a,b-unsaturated ketone 141. The tandem Michael ÀDieckmann type reaction of 141 with the isobenzo- The first total synthesis of a pseudo-dimer of tetracycline, furanone 142 gave the tetracyclic compound 143.66 One of the key hibarimicinone problems of this synthesis was the stereoselective introduction of a Hibarimicins, isolated from the culture broth of Microbispora rosea hydroxyl group at C12a. Manipulation of the protective groups of 143 subsp. hibaria, have been known to possess v-Src tyrosine kinase gave the diol 144, which was adequate to oxidate the right wing. The inhibitory activity and differentiation inducing activity of HL-60 primary alcohol of 144 participated in the bromination of C1-12a cells.67,68 Among them, hibarimicinone (150) has the most potent olefin to give the desired 145.Treatmentof145 with a mixture of activity of v-Src tyrosine kinase inhibition without differentiation pyridinium chlorochromate and pyridinium dichromate in inducing activity. The structure of hibarimicinone (150) has been dichloromethane, followed by purification with silica gel, afforded disclosed to be a fascinating pseudo-dimer of tetracycline, which the aldehyde 146 in 61% yield. This transformation realized the includes 13 stereogenic centers as well as the axial chirality concurrent oxidation of primary and secondary alcohols accompanied (Figure 19). On this final chapter, the author presents the first total by introduction of the C12a hydroxyl group. The resulting 146 synthesis of hibarimicinone (150).69,70 was converted to the nitrile 147 by a newly-developed method The strategy chosen to construct the eight-ring skeleton was a using hydroxylamine followed by dehydration with 1,10- double Michael ÀDieckmann type cyclization2–6,64,71 using the chiral carbonyldiimidazole. The nitrile 147 was transformed through 148 biaryl thiolactone 152 (DE segment) and the chiral decalin 151

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 119

OH H2C O 1) Se 1)BH3•THF DBU O H O /NaOH BnO O BnO PhMe O 2 2 HgCl2 OBn NO OBn OBn H2C OBn 2 HO OMe 2 ) BnBr OMe OH 2 ) MsCl OMe Et N NHZ NHZ NHZ NHZ 3 CH2Cl2 135 136 137 138 Me

O NHZ Me NHZ 6 OTMS CrO H OMe O SOCl H 3 3 2 H SO OBn Et N OBn 2 140 2 4 4 142 3 6 5 4 OBn 5 OBn 12a 1 OBn BnO DBMP LDA 3 170 °C NHZ O OH OMe OH O OH 139 141 143

Me NHBoc Me NHBoc H Me NHBoc H H 1) NH2OH Br2 OH OH 1) PCC, PDC OH 2) CDI (Bu3Sn)2O 12a Br 12a 12a 1 OH O 2) Silica gel OMe OH OMe OH O OMe OMe OH O OMe OH O O O 144 145 146 Me Me Me Me Me Me Me NHBoc Me N N Me OH N H Me OOH H H H H O H OH OH 2 OH 2 OH 6 hν, TPP 6 Pt-black 6 5 4 A O O 12a 1 O CN OH OH OH OH OMe OH O O OH OH O O NH2 OH O O O NH2 OH O OH O NH2 147 148 149 8: (–)-Tetracycline

Figure 18 Total synthesis of natural ( À)-tetracycline.

HO OMe Me SnCl4-promoted aldol condensation of 156 resulted in the formation H 8 6 HO 4 OMe of the key enone 157. Diels ÀAlder reaction proceeded 10 O OH O 12 H G F E 14 1' 17 ' OH stereoselectively to give adduct 158, which possessed the desired 9R HO OH 17 1 configuration (hibarimicinone numbering). Jones oxidation, HO OH D C B O A 12' O OH OH converting the allyl trimethysilyl ether to the enone, and the MeO 3' OH 6' 8' H 10' Me O OH OH subsequent reduction with SmI2 to remove the sulfone gave the Sm(III) enolate 159, which was oxidized to provide stereoselectively 150:Hibarimicinone the tertiary alcohol 160. The C10a-alcohol 160 was converted into the b-alcohol 161 through regio- and stereoselective de-O-silylation, oxidation and reduction. Protection of the tertiary alcohol of 161 accompanied with formation of the dienyl silyl ether 162 as desired in TMSO OMe H Me the right ring, and the subsequent Grignard reaction introduced an TBSO OMe TMSO allyl group in a stereoselective manner to give the tertiary alcohol 163. HG S E MOMO O O OTMS TBSO OTBS After silylation of the tertiary alcohol, treatment of the dienyl silyl O TMSO O OMOM DAS B ether with DBU in hot toluene in the presence of i-PrOH promoted OTMS MeO OTBS the regioselective de-silylation, followed by hydrogenation of the exo Me H OMe OnBu OTMS olefin to yield the enone decalin segment 151 corresponding to the 151 152 151 AB and GH segments (Figure 20). Figure 19 Retrosynthesis of hibarimicinone. For constructing the DE segment, the chiral biaryl thiolactone 152 was obtained as shown in Figure 21. The commercially available carboxylic acid 164 was converted into 165 through ortho-lithiation- (AB and GH segments) in Figure 19. Difference of the oxidation stage methylation of the corresponding amide and regioselective de-O- of thiolactones in biaryl 152 should reflect the oxidation stage of CD methylation. Phenol 165 was subjected to oxidative dimerization by and EF rings. At first, the synthesis of decalin 151,thecommon using silver trifluoroacetate, and the resulting bisphenol was protected structure of AB and GH rings, started from the enone 157,72–74 which as benzoate 166. Two benzylic positions of 166 were brominated and was derived from D-arabinose 153 through D-arabinonic acid g- the sequential substitution with thioacetate ion and methanolysis lactone 154 (Figure 20). This methodology had already been produced the thiolactones 167 with free phenols. The racemic biaryl developed for synthesis of progesterone receptor ligands, PF1092s in 167 was converted to the diastereo-mixture of mono-camphanate, our laboratories,72 and applied to the total syntheses of pyralomicin which was resolved by column chromatography and subsequent 1c,73 valienamine and validamine.74 The phenylsulfonate 155 was crystallization to give the optically pure 168 (R* ¼ ( À)-camphanyl silylated to the opened chain enolate 156 in one step by simultaneous group) in good yield. The desired isomer 168 was converted into formation of an enol silyl ether and an O-silyl secondary alcohol. The symmetrically protected 169. Mono-bromination of 169 and

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 120

MeO TBSO OH OH OTBS TBSOTf HO TrO MeO TBSO OMe O O O OH 2,6-lutidine OH O OMe SnCl4 SO Ph CH Cl 2 CH2Cl2 TBSO SO2Ph 2 2 ° –78 °C,15min OH OH OTBS 40 C, 24 h TBSO 94% 71% 153:D-Arabinose 154 155 156

TBSO TBSO TBSO TBSO OTMS H 1) Jones reagent H Oxone H TBSO 9 TBSO TBSO TBSO DTBC 10 acetone,94% NaHCO aq. 10 11 10 9 3 14 14 14 PhMe TBSO 12 SO2Ph TBSO 2) SmI2 TBSO TBSO 90 °C O O OTMS THF,-78 °C O O 89% O O 90% SO2Ph Sm OH 157 158159 160 1) TMSOTf 2,6-lutidine ClCH CH Cl HO TMSO TMSO 2 2 TMSO H TMSOTf H H 2) DBU/i-PrOH H TBSO TBSO MgCl TBSO TBSO 10 2,6-lutidine PhMe A(H) B(G) 14 14 14 ClCH CH Cl Et O 13 TBSO 2 2 TBSO 13 15 2 TBSO 15 3) H2 / Pd-C TBSO 80 °C 0°C O O O OTMS HO OTMS PhMe TMSO 88% 86% O OH TMSO OTMS 72% (3steps) OTMS Me 161 162 163 151

Figure 20 Synthesis of AB and GH segments of hibarimicinone.

1) dibromo- OMe OMe OMe OMe 1) CF3CO2Ag dimethylhydantoin OMe Me OMe Me OMe AIBN/CCl OMe Et3N/ClCH2CH2Cl 4 S HO MeO MeO 2) BzCl / Py 2) AcSK / THF O OMe O HO 50% (2 steps) O OBz then MeONa O HO 2 69% (2 steps) 2 164 165 166 167

OMe OMe OMe 1) dibromo- OMe OMe OMe (-)-camphanicchloride 1) MeONa dimethylhydantoin Et N/ClCH CH Cl S R*O S MOMO S E MOMO 3 2 2 O MeOH-THF O AIBN / CCl4 O

43% O O O HO S 2) MOMCl / i-Pr2NEt OMOM S 2) n-BuOH/Et3N OMOM D S 69% (2steps) MeO CH2Cl2 MeO MeO (Resolution) 90% (2steps) OnBu OMe OMe OMe 168 169 152

Figure 21 Synthesis of DE segment of hibarimicinone.

substitution with n-butanol were performed in one pot to give the its labile keto form in G ring, the latter of which was smoothly chiral biaryl 152. converted into the enol 170 in the presence of LiCl. Hydrolysis of With both segments 151 and 152 in hand, their conversion to an semithioacetal was performed with AgNO3, and the subsequent eight-ring skeleton in a one-pot reaction was explored (Figure 22). In treatment with DBU gave the hydroquinone at the C ring, followed preliminary studies, we found that Michael ÀDieckmann type cycli- by oxidation of the C ring and aromatization of F ring, including zation using the non-substituted benzothiolactone (the left ring type elimination of thioether and tautomerization to afford 171 in one of 152) proceeded in THF, while the cyclization with the alkoxyben- pot. The ether bond crossing the AB rings was formed with excess zothiolactone (the right ring type) was promoted in toluene. Pyridine amounts of LiI by enolization at the BC rings, followed by conjugate suppressed generation of polymerized products. Therefore, the enone addition to the enone 172.Thesimultaneousde-O-methoxymethyla- 151 and bis-thiolactone 152 were treated with base in the mixed tion gave the free phenols (D and E rings) in 173.Theresulting173 solvent including THF, toluene and pyridine to promote double was immediately oxidized to the quinone 174.Finally,de-O-silylation Michael ÀDieckmann type cyclization to give the eight rings, and the as well as de-O-methylation and tautomerization at the CD rings were resulting thiolates were methylated to provide the enol form 170 and achieved under the acidic conditions to give hibarimicinone (150),

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 121

TMSO H TBSO

TBSO TMSO OMe O TMSO SMe OMe OTMS H Me 151 1) AgNO3 OMe Me TB SO OMe TMSO NaHMDS PhMe-acetone-H2O S MOMO O G F MO MO O HO MeI OTMS 2) DBU, PhMe TB SO OTBS O TMSO OMOM S THF-PhMe-Py OH O OMOM C 3) Ag2CO3 Me O -20 °C, 20 min OTMS MeO OTBS PhMe-acetone-H2O OnBu OnBu 57 % Me H then MeI OMe MeO SMe OTMS 63 % (3 steps) 152 170

TMSO OMe TMSO OMe H Me H Me TBSO OMe TBSO OMe TMSO Li TMSO F MOMO O O LiI MOMO OH O OTMS OTMS TBSO OTBS TBSO OTBS MeCN TMSO C B A TMSO C B A O HO OMOM ClCH CH Cl O HO OMOM OTMS 2 2 OTMS MeO OTBS 50 °C, 3 h MeO OTBS Me H Me H MeO O OTMS MeO O OTMS Li 171 172

TMSO OMe TMSO OMe H Me H Me TB SO OMe TMSO TBSO OMe TMSO E HO OH O DDQ OH O O TB SO OTBS TBSO OTBS TMSO O O HO OH D THF TMSO O HO OH D C O OTMS toluene MeO OTBS OTMS Me O OTBS Me H 0°C,5min Me H MeO OH OTMS 70 % (2 steps) MeO O OTMS 173 174

HO OMe H Me HO OMe O OH O 1N HCl-MeOH OH OH HO OH OH O 40 °C, 3 h O OH OH 80 % MeO OH H Me O OH OH 150:Hibarimicinone

Figure 22 Total synthesis of hibarimicinone. completing the first total synthesis.69,70 This is the 102nd accomplish- ACKNOWLEDGEMENTS ment of total syntheses by the author. The author would like to thank all of his co-workers whose names appear in the references for their intellectual contribution and hard work, and he is also CONCLUSION grateful for financial support from the Research Institute for Science and The total synthesis of the big four antibiotics as well as the related Engineering, Waseda University and the Consolidated Research Institute for Advanced Science and Medical Care, the Global COE program ‘Center for antibiotics are reviewed. Most of the total syntheses that have Practical Chemical Wisdom’, and Scientific Research on Priority Area ‘Creation been completed in our laboratories have been the first ever of Biologically Functional Molecules’ from the Ministry of Education, Culture, accomplished. Establishment of the total syntheses by use of Sports, Science and Technology. carbohydrates as chiral sources created a comprehensive method to investigate a variety of bioactive natural products. The achievement of successful results in research is, of course, of prime importance. Yet, before undertaking research, it is essential that the objectives of the 1 Gabor, L. & Ohno, M. Recent Progress in the Chemical Synthesis of Antibiotics (Springer-Verlag, Heidelberg, 1990). research are clearly understood and defined. Hence, it may be no 2 Tatsuta, K. Total syntheses of useful bioactive compounds. Adv. Synth. Catal. 2001, exaggeration to say that the selection of target molecules decides, 143–159 (2001). 3 Tatsuta, K. Significance of total synthesis of bioactive compounds. Curr. Org. Chem. above all, the value of the research itself, particularly with respect to 2001, 207–231 (2001). bioactive natural product synthesis. In essence, the author believes 4 Tatsuta, K. & Hosokawa, S. Total synthesis of selected bioactive natural products: that the most important factor is to make the utmost effort towards illustration of strategy and design. Chem. Rev. 105, 4707–4729 (2005). 5 Tatsuta, K. & Hosokawa, S. Total synthesis of polyketide-derived bioactive natural realizing one’s goals, that is, to synthesize a target molecule by one’s products. Chem Rec. 6, 217–233 (2006). own concepts and strategies. However, through completion of such 6 Tatsuta, K. Total synthesis and development of bioactive natural products. Proc. Jpn. enterprise and skill, one can certainly produce the ‘art’, as mentioned Acad., Ser. B. 84, 87–106 (2008). 7 Tatsuta, K., Nakagawa, A., Maniwa, S., Amemiya, Y. & Kinoshita, M. Stereospecific in the introduction, which becomes manifest in the reactions and/or total synthesis and absolute configuration of a macrocyclic lactone antibiotic, products. A26771B. Tetrahedron Lett. 21, 1479–1482 (1980).

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8 Tatsuta, K., Tanaka, A., Fujimoto, K., Kinoshita, M. & Umezawa, S. Synthesis of 42 Kanai, T., Morita, Y., Shinohara, H., Kai, Y. & Ogura, K. Reaction of insoluble 2-(5- carbomycin B. Introduction of the amino disaccharide onto the 16-membered-ring amino-1,2,4-thiadiazol-3-yl)-2-((fluoromethoxy)imino)acetic acid with insoluble PCl5 aglycone. J. Am. Chem. Soc. 99, 5826–5827 (1977). in CH2Cl. Chem. Express. 7, 805–806 (1992). 9 Tatsuta, K., Amemiya, Y., Maniwa, S. & Kinoshita, M. Total synthesis of carbomycin B 43 Tatsuta, K., Miura, S., Gunji, H., Tamai, T. & Inagaki, T. A practical preparation of (Z)- and josamycin (leucomycin A3). Tetrahedron Lett. 21, 2837–2840 (1980). 2-(5-amino-1,2,4-thiadiazol-3-yl)-2-(methoxyimino)acetic acid. Tetrahedron Lett. 34, 10 Tatsuta, K., Amemiya, Y., Kanemura, Y. & Kinoshita, M. Synthesis of tylonolide, an 6423–6426 (1993). aglycone of tylosin. Tetrahedron Lett. 22, 3997–4000 (1981). 44 Tatsuta, K. et al. Practical preparation of (Z)-2-(5-amino-1,2,4-thiadiazol-3-yl)-2- 11 Tatsuta, K., Amemiya, Y., Kanemura, Y., Takahashi, H. & Kinoshita, M. Total synthesis methoxy-iminoacetic acid: a side-chain of the fourth generation of cephem antibiotics. of tylosin. Tetrahedron Lett. 23, 3375–3378 (1982). Bull. Chem. Soc. Jpn. 67, 1701–1707 (1994). 12 Corey, E. J. & Nicolaou, K. C. Efficient and mild lactonization method for the synthesis 45 Miyake, A. et al. Studies on condensed-heterocyclic azolium cephalosporins. of macrolides. J. Am. Chem. Soc. 96, 5614–5616 (1974). J. Antibiot. 45, 709–720 (1992). 13 Tatsuta, K., Fujimoto, K., Kinoshita, M. & Umezawa, S. A novel synthesis of 2-deoxy-a- 46 Woodward, R. B. The total synthesis of a tetracycline. Pure Appl. Chem. 6, 561–574 glycosides. Carbohydr. Res. 54, 85–104 (1977). (1963). 14 Okamoto, R. et al. New macrolide antibiotics produced by mutants from Streptomyces 47 Stork, G., La Clair, J. J., Spargo, P., Nargund, R. P. & Totah, N. Stereocontrolled fradiae NRRL 2702. J. Antibiot. 35, 921–924 (1982). synthesis of (±)-12a-deoxytetracycline. J. Am. Chem. Soc. 118, 5304–5305 (1996) 15 Tatsuta, K., Kobayashi, Y., Gunji, H. & Masuda, H. Synthesis of oleandomycin through and references cited therein. the intact aglycone, oleandolide. Tetrahedron Lett. 29, 3975–3978 (1988). 48 Tatsuta, K., Yoshimoto, T., Gunji, H., Okado, Y. & Takahashi, M. The first total synthesis 16 Tatsuta, K., Ishiyama, T., Tajima, S., Koguchi, Y. & Gunji, H. The total synthesis of of natural ( À)-tetracycline. Chem. Lett. 2000, 646–647 (2000). oleandomycin. Tetrahedron Lett. 31, 709–712 (1990). 49 Charest, M. G., Lerner, C. D., Brubaker, J. D., Siegel, D. R. & Myers, A. G. A convergent 17 Toshima, K. et al. Application of highly stereocontrolled glycosidations employing 2,6- enantioselective route to structurally diverse 6-deoxytetracycline antibiotics. Science. anhydro-2-thio sugars to the syntheses of erythromycin A and olivomycin A trisacchar- 308, 395–396 (2005). ¯ ide. J. Am. Chem. Soc. 117, 3717–3727 (1995). 50 Omura, S. et al. Nanaomycins A and B, new antibiotics produced by a strain of 18 Toshima, K. & Tatsuta, K. Recent progress in O-glycosylation methods and its Streptomyces. J. Antibiot. 27, 363–365 (1974). ¯ application to natural product synthesis. Chem. Rev. 93, 1503–1531 (1993). 51 Omura, S., Tanaka, H., Okada, Y. & Marumo, H. Isolation and structure of nanaomycin 19 Toshima, K. et al. Novel glycosidation method using 2,6-anhydro-2-thio sugars for D, an enantiomer of the antibiotic kalafungin. J. Chem. Soc., Chem. Commun. (1976) stereocontrolled synthesis of 2,6-dideoxy-a-and-b-glycosides. J. Am. Chem. Soc. 320–321 (1976). 116, 9042–9051 (1994). 52 Tatsuta, K., Akimoto, K., Annaka, M., Ohno, Y. & Kinoshita, M. Enantiodivergent total 20 Igarashi, M. et al. Tubelactomicin A, a novel 16-membered lactone antibiotic, from syntheses of ( À)-nanaomycin D and its enantiomer, ( þ )-kalafungin. J. Antibiot. 38, Nocardia sp. I. Taxonomy, production, isolation and biological properties. J. Antibiot. 680–682 (1985). 53, 1096–1107 (2000). 53 Tatsuta, K., Akimoto, K., Annaka, M., Ohno, Y. & Kinoshita, M. Enantiodivergent total 21 Hosokawa, S., Seki, M., Fukuda, H. & Tatsuta, K. Total synthesis of an antitubercular syntheses of nanaomycins and their enantiomers, kalafungins. Bull. Chem. Soc. Jpn. 58, 1699–1706 (1985). lactone antibiotic, ( þ )-tubelactomicin A. Tetrahedron Lett. 47, 2439–2442 (2006). 54 Tatsuta, K., Ozeki, H., Yamaguchi, M., Tanaka, M. & Okui, T. Enantioselective total 22 Motozaki, T. et al. Total synthesis of ( þ )-tubelactomicin A. 2. Synthesis of the upper- synthesis of medermycin (lactoquinomycin). Tetrahedron Lett. 31, 5495–5498 half segment and completion of the total synthesis. Org. Lett. 7, 2265–2267 (2005). (1990). 23 Miyaura, N. & Suzuki, A. Palladium-catalyzed cross-coupling reactions of organoboron 55 Tsukamoto, M. et al. New cytotoxic agents, BE-52440A and B, produced by a compounds. Chem. Rev. 95, 2457–2483 (1995). Streptomycete. J. Antibiot. 53, 687–693 (2000). 24 Shiina, I., Kubota, M. & Ibuka, R. A novel and efficient macrolactonization of o- 56 Tatsuta, K., Suzuki, Y., Toriumi, T., Furuya, Y. & Hosakawa, S. The first total synthesis hydroxycarboxylic acids using 2-methyl-6-nitrobenzoic anhydride (MNBA). Tetrahedron and structural determination of ( þ )-BE-52440A. Tetrahedron Lett. 48, 8018–8021 Lett. 43, 7535–7539 (2002). (2007). 25 Shindo, K., Iijima, H. & Kawai, H. Studies on cochleamycins, novel antitumor 57 Iwai, Y. et al. OM-173, new nanaomycin-type antibiotics produced by a strain of antibiotics II. Physico-chemical properties and structure determination. J. Antibiot. Streptomyces. J. Antibiot. 36, 1268–1274 (1983). 49, 244–248 (1996). 58 Kasai, M. et al. Structure of nanaomycin E, a new nanaomycin. J. Antibiot. 32, 26 Tatsuta, K., Narazaki, F., Kashiki, N., Yamamoto, J. & Nakano, S. The first total 442–445 (1979). synthesis of cochleamycin A and determination of the absolute structure. J. Antibiot. 59 Tatsuta, K., Hirabayashi, T., Kojima, M., Suzuki, Y. & Ogura, T. The first total synthesis 56, 584–590 (2003). of a pyranonaphthoquinone antitumor, BE-54238B. J. Antibiot. 57, 291–297 (2004). 27 Dineen, T. A. & Roush, W. R. Total synthesis of cochleamycin A. Org. Lett. 6, 60 Matsumoto, N. et al. Lactonamycin, a new antimicrobiral antibiotic produced by 2043–2046 (2004). Streptomyces rishiriensis. J. Antibiot. 49, 953–954 (1996). 28 Tatsuta, K. & Hosokawa, S. Total synthesis of complicated natural products from 61 Matsumoto, N. et al. Lactonamycin, a new antimicrobiral antibiotic produced by simple carbohydrates. Curr. Org. Chem. (2008) 207–231 (2008). Streptomyces rishiriensis MJ773-884. II. Structure determination. J. Antibiot. 52, 29 Kita, Y., Maeda, H., Omori, K., Okuno, T. & Tamura, Y. J. Novel efficient synthesis of 1- 276–280 (1999). ethoxyvinyl esters using ruthenium catalysts and their use in acylation of amines and 62 Parsons, P. J., Waters, A. J., Walter, D. S. & Board, J. A new route to highly 0 alcohols: synthesis of hydrophilic 3 -N-acylated oxaunomycin derivatives. Chem. Soc., functionalized heterocyclic rings. J. Org. Chem. 72, 1395–1398 (2007). Perkin Trans. 1, 2999–3005 (1993). 63 Siu, T., Cox, C. D. & Danishefsky, S. J. Total synthesis of lactonamycinone. Angew. 30 Tatsuta, K., Suzuki, Y., Furuyama, A. & Ikegami, H. The first total synthesis of a Chem. Int. Ed. 42, 5629–5634 (2003). tetracyclic Antibiotic, ( À)-tetrodecamycin. Tetrahedron Lett. 47, 3595–3598 (2006). 64 Tatsuta, K., Tanaka, H., Tsukagoshi, H., Kashima, T. & Hosokawa, S. The first total 31 Umezawa, S., Tatsuta, K. & Tsuchiya, T. Studies of aminosugars. XII. The absolute synthesis of lactonamycin, a hexacyclic antitumor antibiotic. Tetrahedron Lett. 51, structure of kanamycin as determined by a copper complex method. Bull. Chem. Soc. 5546–5549 (2010). Jpn. 39, 1244–1248 (1966). 65 Tatsuta, K. & Hosokawa, S. Total synthesis of bioactive natural products from 32 Umezawa, S., Koto, S. & Tatsuta, K. The total synthesis of kanamycin B. J. Antibiot. carbohydrates. Sci.Tech.Adv.Mater.7, 397–410 (2006). 21, 424–425 (1968) and references cited therein. 66 Tatsuta, K., Yamazaki, T., Mase, T. & Yoshimoto, T. The first total synthesis of a 33 O’Connor, S., Lam, L. K. T., Jones, N. D. & Chaney, M. O. Apramycin, a unique bioxanthracene ( À)-ES-242-4, an N-methyl-D-aspartate receptor antagonist. Tetrahe- aminocyclitol antibiotic. J. Org. Chem. 41, 2087–2092 (1976). dron Lett. 39, 1771–1772 (1998). 34 Awata, N. et al. Saccharocin, a new aminoglycoside antibiotic fermentation, isolation, 67 Kajiura, T. et al. Biosynthesis of hibarimicins II. Elucidation of biosynthetic pathway by characterization and structural study. J. Antibiot. 36, 651–656 (1983). cosynthesis using blocked mutants. J. Antibiot. 55, 53–60 (2002) and references 35 Tatsuta, K. et al. Total synthesis of aminoglycoside antibiotics, apramycin and cited therein. saccharocin (KA—5685). Bull. Chem. Soc. Jpn. 57, 529–538 (1984). 68 Igarashi, Y. et al. Biosynthesis of hibarimicins III. Structures of new hibarimicin-related 36 Mukaiyama, T., Murai, Y. & Shoda, S. An efficient method for glucosylation of hydroxy metabolites produced by block mutants. J. Antibiot. 55, 61–70 (2002). compounds using glucopyranosyl fluoride. Chem. Lett. 1981, 431–432 (1981). 69 Tatsuta, K. et al. The first total synthesis of hibarimicinone, a potent v-Src tyrosine 37 Kahan, J. S. et al. Thienamycin, a new b-lactam antibiotic I. Discovery, taxonomy, kinase inhibitor. Tetrahedron Lett. 53, 422–425 (2012). isolation and physical properties. J. Antibiot. 32, 1–12 (1979). 70 Tatsuta, K. Recent progress in total synthesis of bioactive natural products. Abstracts of 38 Berks, A. H. Preparations of two pivotal intermediates for the synthesis of 1-b-methyl Papers of The 2nd Tishler-O¯ mura Symposium, Tokyo (2011). carbapenem antibiotics. Tetrahedron. 52, 331–375 (1996). 71 Tatsuta, K. et al. The first total synthesis and structural determination of antibiotics 39 Salzmann, T. N., Ratcliffe, R. W., Christensen, B. G. & Bouffard, F. A. A stereocon- K1115B1s (alnumycins). Tetrahedron Lett. 52, 983–986 (2011). trolled synthesis of ( þ )-thienamycin. J. Am. Chem. Soc. 102, 6161–6163 (1980). 72 Tatsuta, K. et al. Total synthesis of progesterone receptor ligands, ( À)-PF1092A, B and 40 Reider, P. J. & Grabowski, E. J. J. Total synthesis of thienamycin: a new approach from C. Tetrahedron Lett. 38, 1439–1442 (1997). aspartic acid. Tetrahedron Lett. 23, 2293–2296 (1982). 73 Tatsuta, K., Takahashi, M. & Tanaka, N. The first total synthesis of pyralomicin 1c. 41 Tatsuta, K., Takahashi, M., Tanaka, N. & Chikauchi, K. Novel synthesis of ( þ )-4- J. Antibiot. 53, 88–91 (2000). acetoxy-3-hydroxyethyl-2-azetidinone from carbohydrate. Total synthesis of ( þ )-thie- 74 Tatsuta, K., Mukai, H. & Takahashi, M. Novel synthesis of natural pseudo-aminosugars, namycin. J. Antibiot. 53, 1231–1234 (2000). ( þ )-valienamine and ( þ )-validamine. J. Antibiot. 53, 430–435 (2000).

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 123

Structures of the 102 Synthesized Compounds

OH NH2 NH2 NH2 O O O HO HO HO O HO HO HO HO NH2 NH2 HO H N HO H2N NH2 2 O OH O OH O H2N OH HO NH HO NH O 2 2 HO O HO O HO NH2 O HO HO OH H2N H2N HO HO OH O O 1: Neamine 2: Trehalosamine 3: Kanamycin A 4: Kanamycin B (1967) (1967) (1968) (1968)

OH HO O O O HO NH HO2C CH NH CNHCH CO X NH CH CHO HO2C CH NH CNHCH CO X NH CH CHO H N 2 2 O CH CH CH CH OH 2 NH 2 2 NH 2 HO NH2 HO O H2N N NH N NH HO H H O 5: Kanamycin C 6: Chymostatin A: X=L-Leu 7: Chymostatin B: X=L-Val (1968) (1973) (1973)

OH O Me Me CHO O CHO Me Me HO2C CH NH CNHCH CO X NH CH CHO Me Me N MeO HO CH CH N 2 NH 2 MeO HO O O O MeO OH O O O O Me OH Me N NH Me Me O OAc O O Me H Me O OAc O O Me Me Me OMe 8: Chymostatin C: X=L-Ile 9: Carbomycin B OMe 11: Leucomycin A3 (1973) (1977) (1980)

O Me Me OH Me O OCO HO OH Me Me H H OH O O Me N Me HO Me COOH O O O Me Me H H H O O O O OMe OH O Me Me 10: Hirsutene 12: Coriolin 13: A26771B O OH (1979) (1980) (1980) Me 14: Erythromycin A (1981)

O OH Me O CHO H2N Me HO OH Me Me Me OH NH H HOH OH HO Me N O Me HO O HO O O O O O O MeO OH OH N N H N NH2 OMe Me 2 O OMe O OH OH O HO NH2 Me Me HO 15: Tylosin 16: Isoretronecanol 17: Rosmarinecine 18: Apramycin (1981) (1982) (1982) (1983)

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 124

Structures of the 102 Synthesized Compounds (continued)

OH H2N NH HO O Me C OH O Me OH O Me HO NH OH NH HO O O O CH2 O O CH2 H N NH2 2 O CH2 CH2 O O O O HO NH2 H2NCHCOCH2CHCO2H O O HO 5 2 19: Saccharocin 20: Arphamenine A (2R,5S) 22: Nanaomycin D 23: Kalafungin (1983) 21: Epi-arphamenine A (2S,5S) (1985) (1985) (1983)

OH HO Me

O Me Me Me OH O Me OH AcO Me Me O O AcO Cl O Cl O OH O O OH O NC NC NO N O O O Me Me Me O CO2H HO H Me Me Me O 24: Nanaomycin A 25: Elaiophylin 26: Indisocin 27: N-Methylindisocin (1985) Me OH (1986) (1987) (1987) OH

O O Me N OH O Me Me Me Me O NH HO NHCHO OH HN N N Me HO O Me HO Me O O O Me OH N NH O O N O H H O O Me 28: Erbstatin 29: Azepinomycin Me OMe N HO O O OH (1987) (1987) Me Me Me 30: Oleandomycin 31: Pyridomycin (1988) (1989)

Me Me Me Me HO

HO OHOH OH Me HO O O OH O Me Me OH O OH OH NH Me N O Me O 2 HO HO O HO HO OH O O NMe2 O HO N Me O O 32: Rifamycin W 33: Cyclophellitol 34: Medermycin (Lactoquinomycin) 35: Allosamizoline (1990) (1990) (1990) (1991)

O Cl O Cl MeO N N H O OH O Me Cl OH Me OMe MeO O N N Me N Me Me N Me Cl MeO O NH2 O Me O Me Cl Me Me 36: Herbimycin A 37: Maniwamycin A 38: Maniwamycin B 39: Neopyrrolomycin (1991) (1993) (1993) (1993)

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 125

Structures of the 102 Synthesized Compounds (continued)

HO OH Me HO OH O O OH O N N Me N O NH2 O HO HO N O O Me N O HO OH HO OH N OHO H O H O CO2H H N HO OH HN HO N Me MeO NHAc O HO HO OH 40: Pyrizinostatin 41: AB3217-A 42: Nagstatin 43: Gualamycin (1994) (1994) (1995) (1995)

OH OH OH OH Me O OH HO O O O HO HO O OH O HO O AcO O OH O H Me Me Me O O O CO2H HO O AcO HO HO Me Me Me Me Me Me Me Me Me

44: Deacetyl-caloporoside 45: Calbistrin A 46: PF1092A 47: PF1092B (1996) (1997) (1997) (1997)

OH O O HO Me O HO HO O Me OH O HO Me HO HO Me Me OH O Me Me OH Me OH 48: PF1092C 49: MS-444 50: Terpestacin 51: KD16-U1 (1997) (1997) (1998) (1998)

MeO OH MeO OH CHO O O HO OH CHO Me Me MeO MeO HO O O O OH CHO HO OH OH OH OMe MeO Me MeO Me OHC HO HO O O OH MeO OH MeO OH 52: Glyoxalase I Inhibitor 53: ES-242-4 54: ES-242-5 55: Sideroxylonal B (1998) (1998) (1999) (1999)

O O CHO OOH OH OH HO OH Cl CHO HO O O Me O Me CHO Cl N O N N OH OH Me Me O Me O OHC O O O OH HO OH OH OH Me Me 56: Sideroxylonal C 57: Pyralomicin 2c 58: PF1163A 59: PF1163B (1999) (1999) (1999) (1999)

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 126

Structures of the 102 Synthesized Compounds (continued)

O OH Cl O O OH Cl N O Me HO Me OH OH Me C H C6H13 N 6 13 N HO HO H OH OH NH2 OH 60: Pyralomicin 1c 61: PC-3 (SF2420B) 62: YM-30059 63: Validamine (2000) (2000) (2000) (2000)

H O N OH Me OH NMe2 HO H H HH MeO HO OH OH Me NH S 2 O OMe HO N OH O O CO H N NH2 OH O OH O NH2 2 H

64: Valienamine 65: Tetracycline 66: Thienamycin 67: Asterriquinone B1 (2000) (2000) (2000) (2001)

H CHO O N HO OH HO MeO O O O HO O Me OH OH O O HN HO O N O H N MeO O H Me OH HO

68: Demethylasterriquinone B1 69: Quinolactacin B 70: LL-Z1640-2 71: Luminacin C1 (2001) (2001) (2001) (2001)

O CHO Cl O OH Cl HO HO OH O OH O OH MeO O O OH OH O OH HO O Me O OH O O O O HO OH H Me O O AcO HO HO OH 72: Luminacin C2 73: Napyradiomycin A1 74: UCE6 75: 4-O-(4"-O-Acetyl- -L-rhamnopyranosyl)-ellagic (2001) (2002) (2002) acid (2003) Me Me OOMe H OH O H OH O O H Me HO OAc N N O HO N H AcHN Me Me Me HO O H O O NH H N O OO OH NH2 OOHMe 76: Cochleamycin A 77: Lymphostin 78: BE-54238B 79: Trichostatin D (2003) (2004) (2004) (2005)

OMe OH Me OH Me Me OH Me NC NC H H Me Me O O NC NC MeO HO O O 80: Xanthocillin X dimethylether 81: Xanthocillin X 82: YM182029 83: AM6898D (2005) (2005) (2005) (2005)

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 127

Structures of the 102 Synthesized Compounds (continued)

CO2H Me Me HO Me Me O Me O Me Me Me Me Me Me O O H MeO OMe O Me O N Me Me N OH Me Me H H O HO O O N O Me OH H Me O OH 84: Tubelactomicin A 85: Tetrodecamycin 86: Actinopyrone A 87: Lagunamycin (2006) (2006) (2006) (2006)

HOOC

HO O O O Me O N Me Me Me Me OH O Me HO HO O OH HO Me O HO HO2C O O Me O OH O O O O CO2H N MeO O CO2Me OH O 88: Vinaxanthone 89: YCM1008A 90: TMC-66 91: OM-173 E (2007) (2007) (2007) (2007)

OH O Me OH OO Cl OH O Me HO OH O OMe OMe Me O O S O O MeO MeO O Me O O OCO2H O O MeO2C OH OH OH O Me O OH 92: Nanaomycin E 93: (+)-BE-52440A 94: (–)-TMC-264 95: Nidulalin A (2007) (2007) (2008) (2009) Me

AcO O Me OMe Me O HO N O O Me Me O O MeO OH HO Me OH O O O O Me OH OH OH O O O O O HH H Me Me Me O Me O OMe O HO O MeH H OH

96: Benzopyrenomycin 97: Epi-cochlioquinone A 98: Lactonamycin 99: K1115 B1 (2009) (2010) (2010) (2011)

O OH

HO OMe Me OH H Me OH O O HO OMe O OH O OH OH O O H OH HH HO OMe HO HO O Me O HO HO MeO OH O OH H Me O OH OH OH

100: K1115 B1 101: XR774 102: Hibarimicinone (2011) (2011) (2012)

The Journal of Antibiotics Total synthesis of big four antibiotics and related antibiotics K Tatsuta 128

List of 102 synthesized compounds

The big four antibiotics (aminoglycoside, The ﬁrst total beta-lactam, macrolide No synthesis and tetracycline antibiotics) Compounds Year Journal title Volume no. Issue no. Page range

1 JJNeamine 1967 J. Antibiot. 20 1 53–54 2 JJTrehalosamine 1967 J. Antibiot. 20 6 388–389 3 JJKanamycin A 1968 J. Antibiot. 21 5 367–388 4 JJKanamycin B 1968 J. Antibiot. 21 6 424–425 5 JJKanamycin C 1968 J. Antibiot. 21 2 162–163 6 J Chymostatin A: X ¼ L-Leu 1973 J. Antibiot. 26 11 625–646 7 J Chymostatin B: X ¼ L-Val 1973 J. Antibiot. 26 11 625–646 8 J Chymostatin C: X ¼ L-lle 1973 J. Antibiot. 26 11 625–646 9 JJCarbomycin B 1977 J. Am. Chem. Soc. 99 17 5826–5827 10 Hirsutene 1979 J. Am. Chem. Soc. 101 20 6116–6118 11 JJLeucomycin A3 1980 Tetrahedron Lett. 21 29 2837–2840 12 J Coriolin 1980 J. Antibiot. 33 1 100–102 13 J A26771B 1980 Tetrahedron Lett. 21 15 1479–1482 14 JJErythromycin A 1981 J. Am. Chem. Soc. 103 11 3210–3213 1981 J. Am. Chem. Soc. 103 11 3213–3215 1981 J. Am. Chem. Soc. 103 11 3215–3217 15 JJTylosin 1981 Tetrahedron Lett. 23 33 3375–3378 16 J Isoretronecanol 1982 J. Am. Chem. Soc. 105 12 4096 17 J Rosmarinecine 1982 J. Am. Chem. Soc. 105 12 4096 18 JJApramycin 1983 Tetrahedron Lett. 24 44 4868–4870 19 JJSaccharocin 1983 Tetrahedron Lett. 24 44 4868–4870 20 J Arphamenine 1983 J. Antibiot. 36 12 1787–1788 21 J Epi-arphamenine 1983 J. Antibiot. 36 12 1787–1788 22 J Nanaomycin D 1985 J. Antibiot. 38 5 680–682 23 J Kalafungin 1985 J. Antibiot. 38 5 680–682 24 J (À)-Nanaomycin A 1985 Bull. Chem. Soc. Jpn. 58 6 1699–1706 25 JJElaiophylin 1986 Tetrahedron Lett. 27 39 4741–4744 26 J Indisocin 1987 J. Antibiot. 40 8 1202–1203 27 J N-Methylindisocin 1987 J. Antibiot. 40 8 1202–1203 28 J Erbstatin 1987 J. Antibiot. 40 8 1207–1208 29 J Azepinomycin 1987 J. Antibiot. 40 10 1461–1463 30 JJOleandomycin 1988 Tetrahedron Lett. 29 32 3975–3978 31 J Pyridomycin 1989 Tetrahedron Lett. 30 52 7419–7422 32 JJRifamycin W 1990 Tetrahedron 46 13-14 4629–4652 33 J Cyclophellitol 1990 Tetrahedron Lett. 31 8 1171–1172 34 J Medermycin 1990 Tetrahedron Lett. 31 38 5495–5498 35 Allosamizoline 1991 Tetrahedron Lett. 32 39 5363–5366 36 JJHerbimycin A 1991 Tetrahedron Lett. 32 42 6015–6018 37 J Maniwamycin A 1993 Tetrahedron Lett. 34 38 6095–6098 38 J Maniwamycin B 1993 Tetrahedron Lett. 34 38 6095–6098 39 J Neopyrrolomycin 1993 Tetrahedron Lett. 34 52 8443–8444 40 J Pyrizinostatin 1994 J. Antibiot. 47 3 389–390 41 J AB3217-A 1994 Tetrahedron Lett. 35 19 3099–3102 42 J Nagstatin 1995 Tetrahedron Lett. 36 37 6721–6724 43 J Gualamycin 1995 Tetrahedron Lett. 36 37 6717–6720 44 J Deacetyl-caloporoside 1996 Tetrahedron Lett. 37 14 2453–2456 45 J Calbistrin A 1997 Tetrahedron Lett. 38 4 583–586 46 J PF1092 A 1997 Tetrahedron Lett. 38 8 1439–1442 47 J PF1092 B 1997 Tetrahedron Lett. 38 8 1439–1442 48 J PF1092 C 1997 Tetrahedron Lett. 38 8 1439–1442 49 J MS-444 1997 J. Antibiot. 50 3 289–290 50 J Terpestacin 1998 Tetrahedron Lett. 39 1 83–86 51 KD16-U1 1998 Tetrahedron Lett. 39 6 401–402 52 J Glyoxalase I inhibitor 1998 Tetrahedron Lett. 39 6 401–402 53 J ES-242-4 1998 Tetrahedron Lett. 39 13 1771–1772

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The big four antibiotics (aminoglycoside, The ﬁrst total beta-lactam, macrolide No synthesis and tetracycline antibiotics) Compounds Year Journal title Volume no. Issue no. Page range

54 J ES-242-5 1999 J. Antibiot. 52 4 422–425 55 J Sideroxylonal B 1999 Tetrahedron Lett. 40 10 1925–1928 56 J Sideroxylonal C 1999 Tetrahedron Lett. 40 10 1925–1928 57 J Pyralomicin 2c 1999 Tetrahedron Lett. 40 10 1929–1932 58 J PF1163A 1999 J. Antibiot. 52 12 1146–1151 59 J PF1163B 1999 J. Antibiot. 52 12 1146–1151 60 J Pyralomicin 1c 2000 J. Antibiot. 53 1 88–91 61 J PC-3 2000 J. Antibiot. 53 4 418–421 62 J YM-30059 2000 J. Antibiot. 53 4 418–421 63 Valienamine 2000 J. Antibiot. 53 4 430–435 64 Validamine 2000 J. Antibiot. 53 4 430–435 65 JJTetracycline 2000 Chem. Lett. 2000 6 646–647 66 J Thienamycin 2000 J. Antibiot. 53 10 1231–1234 67 J Asterriquinone B1 2001 J. Antibiot. 54 1 105–108 68 J Demethylasterriquinone B1 2001 J. Antibiot. 54 1 105–108 69 J Quinolactacin B 2001 J. Antibiot. 54 1 109–112 70 J LL-Z1640-2 2001 Chem. Lett. 2001 2 172–173 71 J Luminacin C1 2001 Tetrahedron Lett. 42 43 7625–7628 72 J Luminacin C2 2001 Tetrahedron Lett. 42 43 7625–7628 73 J Napyradiomycin A1 2002 Chemistry Lett. 2002 1 14–15 74 JJUCE 6 2002 J. Antibiot. 55 12 1076–1080 75 J 4-O-(400-O-acetyl-a-L- 2003 J. Nat. Prod. 66 5 729–731 rhamnopyranosyl)-ellagic acid 76 J Cochleamycin A 2003 J. Antibiot. 56 6 584–590 77 J Lymphostin 2004 Tetrahedron Lett. 45 13 2847–2850 78 J BE-5423B 2004 J. Antibiot. 57 4 291–297 79 J Trichostatin D 2005 Tetrahedron Lett. 46 2 333–337 80 J Xanthocillin X dimethyl ether 2005 Tetrahedron Lett. 46 30 5017–5020 81 J Xanthocillin X 2005 Tetrahedron Lett. 46 30 5017–5020 82 J YM182029 2005 Ogura, T. Doctor Thesis, Waseda Univ. 83 J AM6898D 2005 Ogura, T. Doctor Thesis, Waseda Univ. 84 Tubelactomicin A 2006 Tetrahedron Lett. 47 14 2439–2442 85 J Tetrodecamycin 2006 Tetrahedron Lett. 47 21 3595–3598 86 J Actinopyrone A 2006 Tetrahedron Lett. 47 30 5415–5418 87 J Lagunamycin 2006 Tetrahedron Lett. 47 35 6183–6186 88 J Vinaxanthone 2007 Chemistry Lett. 32 1 10–11 89 J YCM1008A 2007 Tetrahedron Lett. 48 24 4187–4190 90 J TMC-66 2007 Tetrahedron Lett. 48 41 7305–7308 91 J OM-173 aE2007Tetrahedron Lett. 48 45 8018–8021 92 J Nanaomycin E 2007 Tetrahedron Lett. 48 45 8018–8021 93 J BE-52440 A 2007 Tetrahedron Lett. 48 45 8018–8021 94 J TMC-264 2008 Tetrahedron Lett. 49 25 4036–4039 95 J Nidulalin A 2009 J. Antibiot. 62 8 469–470 96 J Benzopyrenomycin 2009 Tetrahedron Lett. 50 48 6701–6704 97 J Epi-cochlioquinone A 2010 Tetrahedron Lett. 51 42 5532–5536 98 J Lactonamycin 2010 Tetrahedron Lett. 51 42 5546–5549 99 J K1115 B1a 2011 Tetrahedron Lett. 52 9 983–986 100 J K1115 B1b 2011 Tetrahedron Lett. 52 9 983–986 101 J XR774 2011 Kataoka, Y. Master Thesis, Waseda Univ. 102 JJHibarimicinone 2012 Tetrahedron Lett. 53 4 422–425

The Journal of Antibiotics