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Sulfur-Facilitated Organic Synthesis

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Sulfur-Facilitated Organic Synthesis Sulfur-Facilitated Organic Synthesis Andrew McClory Monday March 16, 2009 8:00 pm, 147 Noyes S S S S S S 'Attempts to make thioacetone by the cracking of trithioacetone gave rise to an offensive smell which spread rapidly over a great area of the town causing fainting, vomiting and a panic evacuation'...'the laboratory work was abandoned.' -Researcher, Freiburg, 1889 S S S 'Attempts to make thioacetone by the cracking of trithioacetone gave rise to an offensive smell which spread rapidly over a great area of the town causing fainting, vomiting and a panic evacuation'...'the laboratory work was abandoned.' -Researcher, Freiburg, 1889 'Recently we found ourselves with an odour problem beyond our worst expectations. During early experiments, a stopper jumped from a bottle of residues, and, although replaced at once, resulted in an immediate complaint of nausea and sickness from colleagues working in a building two hundred yards away. Two of our chemists who had done no more than investigate the cracking of minute amounts of trithioacetone found themselves the object of hostile stares in a restaurant and suffered the humiliation of having a waitress spray the area around them with a deodorant. The odours defied the expected effects of dilution since workers in the laboratory did not find the odours intolerable...and genuinely denied responsibility since they were working in closed systems. To convince them otherwise, they were dispersed with other observers around the laboratory, at distances up to a quarter of a mile, and one drop of either acetone gem-dithiol or the mother liquors from crude thioacetone crystallizations were placed on a watch glass in a fume cupboard. The odour was detected downwind in seconds.' -Esso Researcher, Oxford, 1967 Seminar Overview 1. Nomenclature 6. Olefination 2. Selected Properties A. Julia B. Ramberg-Backlund 3. Elimination C. Eschenmoser D. Corey-Winter A. Burgess E. Nicolaou B. Martin C. Sulfoxide 7. Oxidation D. Chugaev A. Kornblum 4. Radical Reaction B. Moffatt-Swern A. Barton 8. Functionalization B. Zard A. Mislow-Evans 5. C-C Bond Formation B. Pummerer C. DMTSF A. Nature; Fukuyama D. Diels-Alder B. Acyl Anion Equivalents E. Total Synthesis C. Sulfur Ylides E. Chiral Auxiliaries 9. Allium Chemistry Nomenclature of Organosulfur Compounds O O O S S S S S S S R' RSH R R' R R' R S R R' R H R R' R NH2 Thiol Sulfide Sulfoxide Sulfone Disulfide Thioaldehyde Thioketone Thioamide (Mercaptan) (Alkyl Mercaptan) O S O S S S O X O X S S S R OR' R SR' R SR' RO SR' R O Thionoester Thioester Dithioester Xanthate Ester Sulfine Sulfene Sulfonium Salt Sulfoxonium Salt O O O R O O O O S S S S S X S S H2N R Sulfonium ylide Sulfoxonium Ylide Thiirane Episulfonium Salt Episulfone Sulfolane Sulfonamide (Episulfide) S S X R S S S S R S S R Cl R OR' N R OH Thioacetal Ketene Thioacetal R Sulfenyl Chloride Sulfenic Acid Sulfenate Ester (1,3-Dithiane) Thiazolium Salt O O S R' S R' R N O O R S R S S R' S S S S R NH R OR' O O O R R Cl R N R' 2 Thiosulfinate Thiosulfonate Sulfilimine Sulfinyl Chloride Sulfinimine Sulfinamide Sulfinate Ester Selected Properties of Organosulfur Compounds pKa Values (DMSO) O O O S S S S S S H2O 45 39 35 31 31 25 S O O SH O O S N SH S S Ph Ph OH Ph OH 18 18 17 10 7 1 Bond Stengths (kcal/mol) Bond Lengths (A) A-Values (kcal/mol) C=S: 120 C=O: 177 C=S: 1.6 C=O: 1.2 Me: 1.7 C-S: 74 C-O: 85 C-S: 1.8 C-O: 1.4 OMe: 0.6 S-H: 87 O-H: 110 S-H: 1.4 O-H: 1.0 SMe: 0.7 S-S: 65 O-O: 43 S-S: 2.0 O-O: 1.5 S=O: 1.5 SOMe: 1.2 SO2Me: 2.5 Elimination Burgess Dehydration O O OH MeO2C S N NEt3 Benzene 25 -> 50 ºC 60$ / gram SO2 MeO2CNH2 O O Et3NH MeO2C S N O H TESO TESO OBOM OBOM O O 7 steps TBSO MeO2C S TBSO Taxol N NEt3 OTMS OH H H O OH O O (63% yield) O O O Atkins, G. M.; Burgess, E. M. J. Am. Chem. Soc. 1968, 90, 4744-4745. Burgess, E. M.; Penton, H. R.; Taylor, E. A. J. Org. Chem. 1973, 38, 26-31. Holton, R. A. et al. J. Am. Chem. Soc. 1994, 116, 1599-1600. Elimination Martin Dehydration OH F3C O O CF3 F C S CF 3 3 CHCl3 Ph Ph Ph Ph -50 ºC -> 25 ºC 57$ / gram O CF3 S F3C O Ph Ph Ph Ph O CF3 CF Ph O 3 Ph S CF3 S CF3 O Ph Ph Ph OH CF3 H F3C O Ph F C CF OH 3 O O 3 F C S CF 3 3 CHCl , 25 ºC Ph Ph Ph Ph 3 (32% yield) Martin, J. C. Arnhart, R. J. J. Am. Chem. Soc. 1971, 93, 4327-4329. Elimination Sulfoxide Ph O Ph O S S R' H R R Benzene R 25 -> 80 ºC R' R' O O O LiCA; LDA; SPh SPh PhSSPh MeI O O mCPBA; Ph S CCl , 70 ºC 4 O H (+/-)-Acorenone Trost, B. M. Acc. Chem. Res. 1978, 11, 453-461. Oppolzer, W.; Mahalanabis, K. K.; Bättig, K. Helv. Chim. Acta. 1977, 60, 2388-2401. Elimination Xanthate Ester S SMe S NaH, CS2; H OH C MeSH Ph O Ph 250 -> 300 ºC MeI Ph O MeS HO S O NaH, THF, CS ; NaHCO O 2 3 O N then MeI, -30 ºC Ph2O, 260 ºC O Cbz N (92% yield) O Cbz (72% yield) H H 6 steps O HO C O 2 N N HO C N O Cbz Cbz 2 O H H H (-)-Kainic Acid Chugaev, L. Ber. Dtsch. Chem. Ges. 1899, 32, 3332. Nakagawa, H.; Sugahara, T.; Ogasawara, K. Org. Lett. 2000, 2, 3181-3183. Radical Reaction Barton O AIBN, O Bu SnH N 3 R Cl NaO N RH R O Benzene, 80 ºC S S H SnBu3 NC Bu3Sn H SnBu3 N N CN CN O R N R O S SnBu3 AIBN, S SMe NaH, CS ; Bu SnH R OH 2 3 RCH3 MeI R O Benzene, 80 ºC Barton, D. H. R.; Serebryakov, E. P. Proc. Chem. Soc. 1962, 309. Barton, D. H. R.; McCombie, S. W. J. Chem. Soc., Perkin Trans. 1 1975, 1574-1585. C-C Bond Formation Nature - Thioester NH2 N N O OH O O H H N N P P N N S O O O H H O O O O O H H O OH O P O Acetyl CoA O O O Fatty Acids, Polyketides O SCoA O HO O O O O OH HO Alkaloids HO OH SCoA SCoA OH O Glucose Pyruvic Acid Acetyl CoA HO2C CO2H FADH2 NADH ATP Synthesis HO CO2H C-C Bond Formation Fukuyama - Thioester iBuOCOCl 10% Pd/C O N-Methylmorpholine; Et3SiH (2-3 equiv) RCO2H RCHO EtSH R SEt Acetone, 25 ºC, 30 min O O Pd (0) R R' R SEt R' = H, R O O R' SEt R Pd R Pd MSEt R'M O O O H O H 1. 5% PdCl (PPh ) O O O O 2 3 2 SEt O O O O IZn O H O H Toluene, 25 ºC, 5 min 2. HCO2H HO2C Phomoidride B tBuO2C (78% yield) Fukuyama, T.; Lin, S-C.; Li, L. J. Am. Chem. Soc. 1990, 112, 7050-7051. Hayashi, Y.; Itoh, T.; Fukuyama, T. Org. Lett. 2003, 5, 2235-2238. Fukuyama, T.; Tokuyama, H. Aldrich. Acta. 2004. 37, 87-96. C-C Bond Formation Acyl Anion Equivalent - Thiazolium Catalyst Cl HO S N HO S Cl N N N Ph NH2 Thiamine 1.30 $ / gram (Vitamin B1) HO S Cl N Ph 17% O O Et3N, EtOH 80 ºC, 90 min OH (74% yield) HO S Cl N Ph O O 10% CN CN Et3N, EtOH 80 ºC, 16 h (75% yield) Stetter, H.; Kuhlmann, H. Org. Syn. 1984, 62, 170. Stetter, H.; Kuhlmann, H.; Haese, W. Org. Syn. 1987, 65, 26. C-C Bond Formation Acyl Anion Equivalent - Thiazolium Catalyst O R Acyl Anion = synthon exhibiting reversal of normal carbonyl group reactivity HO S Cl N Ph O O * Ph Ph S R Ph OH NBn S Cl R' OH N HO Ph S S Ph Ph R 6% yield R NBn NBn O 52% ee OH R' R' S Ph R O NBn Ph R' Breslow, R. J. Am. Chem. Soc. 1958, 80, 3719-3726. Sheehan, J.; Hunnemann, D. H. J. Am. Chem. Soc. 1966, 88, 3666-3667. Sheehan, J.; Hara, T. J. Org. Chem. 1974, 39, 1196-1199. C-C Bond Formation Acyl Anion Equivalent - Thiazolium Catalyst HO S I CN CN N Ph H 2.3 equiv OH H H HO2C Et3N, iPrOH, 80 ºC MeO2C O CO Me CHO O H 2 (67% yield) (+/-)-Hirsutic Acid O HO S Cl O O N Ph 10% O BzO BzO Et3N, Dioxane, 70 ºC (77% yield) N 6 steps NH O Cl OMe Roseophilin Trost, B. M.; Shuey, C. D.; DiNinno, F. J. Am. Chem. Soc. 1979, 101, 1284-1285. Harrington, P. E.; Tius, M. A. J. Am. Chem. Soc. 2001, 123, 8509-8514. C-C Bond Formation Acyl Anion Equivalent - Dithiane MeS SMe nBuLi MeS SMe R SMe THF, -78 ºC R R nBuLi S S S S S S CH2CH2 THF, -78 ºC R R R SH SH + O O nBuLi S E PhI(CF3CO2)2 BF3•Et2O S S S S S S S R E R H CH Cl THF, -78 ºC CH3CN, 25 ºC 2 2 R R E R R O O O O O Electrophiles (E+): R' X R' Cl R' H R' R'' R' R' Corey, E.
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