Silicon Based Cross Coupling Reactions Through Intramolecular Activation

Silicon ─ Based Cross ─ Coupling Reactions Through Intramolecular Activation Yoshiaki Nakao ＊ and Tamejiro Hiyama ＊＊

＊ Department of Material Chemistry, Graduate School of Engineering, Kyoto University

Kyo＊to＊ University Katsura, Nishikyo ─ ku, Kyoto 615 ─ 8510, Japan Research and Development Initiative, Chuo University 1 ─ 13 ─ 27 Kasuga, Bunkyo ─ ku, Tokyo 112 ─ 8551

(Received July 1, 2011; E ─ mail: [email protected]; [email protected])

Abstract: Tetraorganosilanes having a 2 ─ (hydroxymethyl)phenyl group are found to undergo the silicon ─ based cross ─ coupling reaction. The proximal hydroxy group allows transmetalation of alkyl, alkenyl, and aryl groups on silicon to palladium(II), nickel(II), or copper(I or II) to occur, and hence participation in the cross ─ coupling reaction under mild conditions with excellent chemoselectivity. The high stability of the tetraorganosilicon structure is demonstrated by functionalization under various acidic, basic, and oxidative conditions which leave the silyl group completely intact. Moreover, highly efcient synthesis of functional molecules such as oligoarenes has been achieved through iterative cross ─ coupling/O ─ deprotection sequences by simply switching reactivity with orthogonal O ─ protection/deprotection.

hydroxide to generate pentacoordinate silicates in situ ham- 1． Introduction pered application to the synthesis of highly functionalized tar- Metal ─ catalyzed cross ─ coupling reactions have been devel- get molecules and the manufacture of commodity and spe- oped extensively over the last three decades, and applied widely cialty chemicals. Accordingly, efforts have been made to to synthesis of a number of useful substances ranging from overcome these issues and make the silicon ─ based protocol biologically active compounds such as pharmaceuticals and attractive for synthetic chemists. For example, silicon reagents 5 6 7 agrochemicals to organic materials including liquid crystals having silacyclobutyl, electron ─ poor aryl, benzyl, or allyl and uorescent materials, all on scales varying from the labo- groups, 8 which are converted to highly reactive uorosilanes ratory use to the industrial production. Among the main group and/or silanols in situ upon treatment with uoride, have made organometallic coupling partners, organomagnesium, ─ zinc, possible the use of stable tetraorganosilanes in the cross ─ cou- 1 ─ boron, and ─ tin compounds have been extensively utilized. pling reaction. The use of bench ─ stable silanolate salts, on the However, as the result of wide application of cross ─ coupling other hand, has resulted in smooth transformation under mild chemistry even on varying scales, a number of issues have reaction conditions without the need for external activators. 9 come to light with these conventional cross ─ coupling protocols, such as the stability, toxicity, availability and reusability of not only the nucleophilic coupling partners, but also the resultant metal residues. With respect to these issues organosilicon compounds have been expected to have many advantages over other organometallic reagents. Nevertheless, until Hiyama and Hatanaka reported for the rst time in 1988 the cross ─ coupling reaction using tetracoordinate organo(halo)- silanes through formation of pentacoordinate silicate species in situ by the aid of nucleophilic uoride (eq. 1 and Scheme 1), 2 organosilanes had been relatively less employed for cross ─ coupling reaction because of low reactivity due to their high stability. 3 This initial protocol has been further developed reveal- ing several inherent issues associated with the original silicon ─ based cross ─ coupling chemistry while at the same time the Scheme 1. A general catalytic cycle for silicon ─ based cross ─ coupling reactions. importance of the silicon ─ based cross ─ coupling reaction has come to be better recognized. 4 In the original protocol, the use of organosilanes having electron ─ withdrawing halogen or oxygen bound to silicon was considered to be crucial for making the silicon center Lewis ─ acidic enough to promote and stabi- lize the formation of the requisite pentacoordinate silicates. This reagent design makes the organosilicon reagents suscepti- ble to acid ─ or base ─ mediated hydrolysis and thus less attractive for handling by synthetic chemists irrespective of the aforementioned advantages of organosilicon compounds. In addition, the use of such strong nucleophiles as uoride and

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有機合成化学69-11＿05論文_Nakao.indd 27 2011/10/20 11:14:34 Ultimately, however, cross ─ coupling reaction using stable transition metals, hypothesizing that the use of 2 ─ (hydroxy- tetraorganosilanes activated by such a mild base as metal car- methyl)phenyl ─ substituted organosilanes (1 ─ 5, Scheme 5) bonate would appear to be ideal, and a general solution would effect transmetalation of an organic group on silicon addressing all the issues has remained elusive until very without the need for a hydroxyl substituent on the silicon atom recently. itself, and so establish a general strategy for enabling tetraor- The robust C ─ Si bonds of tetraorganosilicon compounds ganosilanes to undergo the cross ─ coupling reactions readily. can be cleaved by intramolecular nucleophilic attack as can be Such reagent design of tetraorganosilanes is partly suggested seen in the Brook rearrangement. 10 In particular, rearrange- by the work of Hudrlik and coworkers on allylation and ben- ment is caused by intramolecular attack of anionic oxygen zylation of carbonyls. 13 such as lithium alkoxides (Scheme 2). C ─ Si bond cleavage as in In this account, we describe how tetraorganosilanes 1 ─ 5 the Brook rearrangement has been successfully combined with undergo transmetalation smoothly to copper, nickel, and pal- 11 transmetalation from silicon to copper (Scheme 3) and palla- ladium, and so participate in cross ─ coupling reactions with dium (Scheme 4). 12 We focused our attention on these smooth aryl and alkenyl halides 14 as well as benzyl carbonates. 15 The transmetalations of tetraorganosilicon compounds to late present cross ─ coupling reactions using the newly developed organosilanes proceed smoothly under reaction conditions Scheme 2. The Brook ─ rearrangement. using metal carbonates as a mild activator owing to the presence of the proximal hydroxy group. Moreover, silicon residue 6 can be recovered readily and reused for the synthesis of further tetraorganosilicon reagents (Scheme 5). 2． Preparation of 2 (Hydroxymethly)phenyl substituted Scheme 3. Transmetalation of [2 ─ (hydroxyalkyl) phenyl](trimethyl) ─ ─ 14,15 ─ silanes to copper. Organosilanes and Related Reagents Typical experimental procedures for the syntheses of common organosilicon compounds are applicable to the preparation of 2 ─ (hydroxymethyl)phenyl ─ substituted tetraorganosilicon compounds. For example, alkenylsilanes 1 are prepared by 16 metal ─ catalyzed hydrosilylation of alkynes using hydrosilanes 7a and 7b, which are readily available from 2 ─ bromoben- zyl alcohol, followed by O ─ deprotection. Platinum ─ catalyzed 17 hydrosilylation gives (E) ─ alkenylsilanes stereoselectively 6c,18 (Table 1), whereas ruthenium ─ catalyzed reactions provides an access to (Z) ─ alkenylsilanes (eq. 2). Alkenylsilanes having a Scheme 4. Cross ─ coupling reaction of (Z) ─ β ─ (trimethylsilyl)acrylic range of functional groups can be prepared by these protocols acid. owing to the excellent chemoselectivity achieved with these well ─ established hydrosilylation reactions, as well as the avail-

Table 1. Hydrosilylation of alkynes with 7a.

Scheme 5. Cross ─ coupling reactions using 2 ─ (hydroxymethyl) ─ phenyl ─ substituted and related organosilanes and their regeneration.

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有機合成化学69-11＿05論文_Nakao.indd 28 2011/10/20 11:14:41 Table 2. Ring ─ opening reactions of cyclic silyl ethers 6 with ability of orthogonally O ─ protected hydrosilanes 7a and 7b. organomagnesium or ─ lithium reagents. Alternatively, simple alkenylsilanes such as vinyl ─ and prope- nylsilanes in addition to a number of arylsilanes and hetero- ar ylsilanes, can be prepared by the ring ─ opening reactions of cyclic silyl ethers 6 with highly nucleophilic organolithium or ─ magnesium reagents (Table 2). A cyclohexane variant of cyclic silyl ether 6’, which was readily prepared through O ─ silylation of 2 ─ hydroxyprop ─ 2 ─ yl ─ substituted cyclohexene fol- 19 lowed by platinum ─ catalyzed intramolecular hydrosilylation, also reacts with aryl Grignard reagents to give the corresponding arylsilanes 2’ in good yields (Scheme 6). The trans stereochemistry of the arylsilyl group and the 2 ─ hydroxylprop ─ 2 ─ yl functionality has been unambiguously conrmed by X ─ ray crystallography of a related 3,5 ─ dinitrobenzoate. Cyclic silyl ether 6a reacts with LiAlH 4, and subsequent one ─ pot O ─ acety- lation gives hydrosilane 7b (eq. 3). These ring ─ opening reactions can be used for regeneration of the tetraorganosilicon reagents since the cyclic silyl ethers are silicon residues obtained in high yields upon completion of the cross ─ coupling reaction (vide infra). The tetraorganosilicon compounds thus obtained tolerate a number of reaction conditions convention- ally employed for functional group manipulations as well as standard basic and acidic work ─ up procedures by virtue of the robust tetraorganosilicon moiety (Scheme 7). 3． Cross coupling of 2 (Hydroxymethyl)phenyl substituted Alken─ylsilanes 14a,14c ─ ─ Scheme 6. Preparation of arylsilanes having cyclohexane ─ based backbone 2’. The reaction of alkenyl[2 ─ (hydroxymethyl)phenyl]dimeth-

ylsilanes (1) with aryl iodides proceeds in the presence of PdCl 2

(1 mol%), (2 ─ furyl) 3P (2 mol%), and K 2CO 3 (2.2 equiv) in DMSO at 35 ℃ to give various alkenylarenes in good yields (Table 3). The reaction can be performed on a gram ─ scale to allow for recovery of cyclic silyl ether 6a in 62% yield by distil- lation from the reaction mixture (entry 3 of Table 3). These reaction conditions employing only the mild carbonate base show excellent tolerance toward common functional groups in both coupling partners. Thus silyl ethers remain intact (entry 9 of Table 3), whereas the use of uoride ─ based activators in the original protocols hampers their applications to silyl ─ protected targets. The arylation of α ─ phenylvinylsilanes, which report- 20 edly suffer from competitive cine ─ substitution, proceeds regiospecically to give 1,1 ─ diarylethenes (entries 28 and 29 of Table 3), demonstrating that the newly designed alkenylsilanes are highly reliable in terms of chemo ─ , stereo ─ and regioselec- tivity. The use of iminophosphine ligand IP 21 is effective for the coupling with (E) ─ and (Z) ─ alkenyl iodides, leading to the corresponding substituted 1,3 ─ dienes with complete retention Scheme 7. Functional group interconversion to prepare of stereochemistry (eq. 4). functionalized alkylsilanes 4b ─ 4g. 4． Cross coupling of 2 (Hydroxymethyl)phenyl substituted Arylsi─lanes 14a,14b,14d,14─e,15 ─

The cross ─ coupling reaction of aryl[(2 ─ hydroxymethyl)- phenyl]dimethylsilanes with aryl halides proceeds in the presence of palladium catalysts and copper cocatalysts. The use of bulky phosphorus ligands such as RuPhos 22 is particularly efcient for a range of aryl electrophiles (Table 4). It is worth not- ing that tributylstannyl and pinacolatoboryl groups in the aryl bromides, both usually believed to be more reactive than silyl functional groups, remain intact, and that the Si ─ Ar bond in the arylsilane is selectively activated to give stannyl ─ or boryl ─ functionalized biaryls (entry 3 of Table 4 and Scheme 8). Spe-

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有機合成化学69-11＿05論文_Nakao.indd 29 2011/10/20 11:14:48 Table 3. Cross ─ coupling reaction of alkenylsilanes 1 with aryl Table 4. Cross ─ coupling reaction of arylsilanes 2 with aryl bromides. iodides.

are modest in some cases due to partial protodesilylation of 6a, possibly at the stage of transmetalation of 6a to copper(I) cleaving the Ar ─ Si bond, when subsequent protonation of the cically, to discriminate the boryl group from the silyl group it resulting Ar ─ Cu bond by protic contaminant would give ben- is better to pretreat the silyl reagent with butyllithium to accel- zyl alcohol, which is also detected by GC (Scheme 9). To erate intramolecular nucleophilic attack (Scheme 8). Again, improve the stability of the cyclic silyl ethers and achieve more successful gram ─ scale synthesis allows for isolation of both the efcient recovery, we designed the isopropyl variant of the biaryl and the cyclic silyl ether 6a in high yields (entry 15 of arylsilane, 2h, which reacts with both aryl bromides and chlo- Table 4). rides without any loss of arylating efciency, and in signi- Yields of cyclic silyl ether 6a as estimated by GC analysis cantly improved yields of the corresponding cyclic silyl ether

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有機合成化学69-11＿05論文_Nakao.indd 30 2011/10/20 11:15:01 Scheme 8. Cross ─ coupling of 2a with borylated aryl bromides. Table 6. Nickel ─ catalyzed cross ─ coupling reaction of arylsilanes 2’ with aryl chlorides.

Scheme 9. Possible fate of 6a under the reaction conditions.

Table 5. Cross ─ coupling reaction of phenylsilane 2h with aryl bromides and chlorides.

Table 7. Nickel ─ catalyzed cross ─ coupling reaction of arylsilane 2’a with aryl tosylates.

6b (Table 5). Another strategy for improving the stability of the arylsilane reagents and the cyclic silyl ethers is demonstrated by switching from 2 ─ (hydroxymethyl)phenyl to 2 ─ (hydroxymethyl)cyclohexyl. The saturated 2 ─ (hydroxyprop ─ 2 ─ yl) ─ substituted arylsilanes thus prepared (Scheme 6) react with aryl chlorides and tosylates in the presence of nickel catalysts (Tables 6 and 7), whereas a related 2 ─ (hydroxymethyl) ─ substituted arylsilane prepared through a similar procedure suffered from competitive oxidation of the hydroxymethyl group. The use of aryl chlorides and arene sulfonates has gained signi- cant importance 23 because of their ready availability from inexpensive arene compounds such as substituted phenols. Moreover, use of nickel catalysts is benecial in terms of the cost of the precious metal catalysts employed. This is in fact the rst example of silicon ─ based biaryl synthesis by nickel The proximal hydroxy group appears crucial for the success catalysis. of the present cross ─ coupling reactions using stable tetraor-

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有機合成化学69-11＿05論文_Nakao.indd 31 2011/10/20 11:15:13 ganosilicon reagents. Protection of the hydroxy group com- Scheme 11. Convergent synthesis of silylated quinquerthiophene. pletely kills the reactivity of the silicon reagents, and causes the C ─ Si bond to remain completely intact under the reaction conditions for the cross ─ coupling. Accordingly, the cross ─ coupling reaction of arylsilane reagents having a free ─ hydroxy group with aryl halides having a O ─ protected 2 ─ (hydroxymethyl)phenyl ─ substituted silyl group gives biaryls retaining the O ─ protected silyl group unchanged. Upon deprotection, the silyl terminus can participate in the cross ─ coupling event. Such iterative cross ─ coupling/deprotection sequences have been performed using various aryl bromides having a THP ─ or acetyl ─ protected silyl group to rapidly assemble highly conju- gated oligoarenes having the 2 ─ (hydroxymethyl)phenyl ─ substituted silyl group at their terminus (Scheme 10). 14d,14e This strategy can be applied to the convergent synthesis of oligothiophenes having silyl groups at both ends (Scheme 11). Some of these silylated quinquerthiophenes serve as novel 24 two ─ photon absorbing materials. By taking advantage of various O ─ protecting groups that can be orthogonally attached and removed, oligoarenes having three silyl moieties with dif- ferent O ─ protections are also accessible by iterative cross ─ coupling/deprotection sequences (Scheme 12). These oligoarenes are generally highly soluble in common organic solvents when compared with their parent arenes due to the presence of the highly hydrophobic triorganosilyl group. This allows common

Scheme 10. Linear synthesis of oligoarenylsilanes through iterative Scheme 12. Linear synthesis of trisilylated oligoarene through cross ─ coupling/deprotection. iterative cross ─ coupling/deprotection.

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有機合成化学69-11＿05論文_Nakao.indd 32 2011/10/20 11:15:24 functional group interconversions including lithiation and Table 9. Cross ─ coupling reaction of methylsilane 3 with aryl halogenation to proceed without any extra care for the silyl bromides and chlorides. functionality (Scheme 11). The arylsilanes also cross ─ couple with various benzyl carbonates to give a variety of diarylmethanes in good yields (Table 8). 15 This diarylmethane synthesis can be performed in the absence of any base, 25 probably because the oxidative addition of the benzyl carbonates to palladium(0) proceeds with liberation of carbon dioxide to afford a palladium alkoxide, which itself acts as a base to promote the transmetalation of the arylsilane reagents with the resultant palladium(II) species. 26

Table 8. Cross ─ coupling reaction of arylsilanes 2 with benzyl methyl carbonates.

5． Cross coupling of 2 (2 Hydroxyprop 2 yl)phenyl substituted A─ lkylsilanes 14f ─ ─ ─ ─ ─ Alkylsilane reagents have also been designed based on this intramolecular activation strategy. Hitherto cross ─ coupling with alkylsilanes has been realized only with alkyl(triuoro)- silanes activated by uoride. 27 Methylation was examined rst. The reaction of 2 ─ [(2 ─ hydroxyprop ─ 2 ─ yl)phenyl]trimethylsilane (3) with aryl chlorides successfully proceeds in the pres- 28 ence of Pd(OAc) 2 (1 mol%), QPhos (4.2 mol%), and K 3PO 4 as base in THF at 100 ℃ to give various methylated arenes in good yields (Table 9). The use of 2 ─ (hydroxymethyl)phenyl ─ trimethylsilane results in oxidation of the hydroxymethyl group to give exclusively 2 ─ (trimethylsilyl)benzaldehyde and con- comitant reduction of the aryl electrophiles (eq. 5). A variety of aryl chlorides and bromides are efciently methylated by the present protocol. In a study on a related reaction, Rauf and Brown have recently disclosed that N ─ (trimethylsilyl)methyl ─ is essential; its absence led to O ─ arylation of 4a and the substituted amides and ureas undergo palladium ─ catalyzed Brook ─ rearrangement through migration of the butyl- oxidative methylation of alkenes possibly through intramolec- (diisopropyl)silyl group to the hydroxy group (eq. 6). Other ular coordination of the aminocarbonyl moiety to promote alkylsilanes 4b ─ 4f having a range of functional groups also transfer of a methyl group to palladium(II). 29 participate in the alkylation of aryl electrophiles (Table 10). The reagent design can be successfully extended to various Cross ─ coupling of sec ─ alkylsilanes was pursued next. Sili- primary alkylsilanes. To avoid selectivity problems, differentia- con ─ based sec ─ alkylation of arene electrophiles has never tion is achieved by using less reactive secondary alkyls rather proved successful except for the case of the γ ─ selective cross ─ 9d,31 than methyl as substituents in the 2 ─ (hydroxymethyl)phenyl ─ coupling of crotylsilanes. To this end, 2 ─ (2 ─ hydroxyprop ─ substituted organosilanes. Accordingly, butyl[2 ─ (2 ─ hydroxy- 2 ─ yl)phenyl(tri ─ sec ─ alkyl)silanes having isopropyl (5a), cyclo- prop ─ 2 ─ yl)phenyl]diisopropylsilane (4a) was chosen and pentyl (5b), or cyclohexyl (5c) groups are prepared. The reac- allowed to react with various aryl bromides in the presence of tion of these sec ─ alkylsilanes with aryl bromides proceeds suc- 30 Pd(OAc) 2 (1 mol%), dppf (4.2 mol%), Cu(hfacac) 2 (3.0 cessfully to give the corresponding sec ─ alkylated arenes in mol%), and K 3PO 4 in THF at 100 ℃ to give butylated arenes good yields in t ─ BuOH in place of THF as solvent (Table 11). in good yields (Table 10). The use of the copper(II) cocatalyst

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有機合成化学69-11＿05論文_Nakao.indd 33 2011/10/20 11:15:31 Table 10. Cross ─ coupling reaction of primary ─ alkylsilanes 4 with aryl bromides and chlorides. 6． Mechanism of the Cross ─ coupling A possible catalytic cycle of the cross ─ coupling reactions using these tetraorganosilicon reagents is suggested in Scheme 13. A general scheme for the palladium ─ catalyzed cross ─ coupling reaction involves oxidative addition of electrophiles to palladium(0) followed by transmetalation and reduc- tive elimination. This is applicable to the silicon ─ based reactions. In particular, the transmetalation step with the silicon reagents proceeds either from silicon directly to palladium or from silicon rst to copper then to palladium. Although the precise mechanism remains elusive, the observed oxidation of the hydroxymethyl group (eq. 5) and O ─ arylation (eq. 6) may imply the formation of transition metal alkoxides which undergo intramolecular transfer of an organic group bound to silicon at its equatorial position. This mechanism has also been suggested for the transmetalation of the same silicon reagents to rhodium. 32 Alternatively, pentacoordinate silicates may be generated upon treatment of the silicon reagents with bases, after which intermolecular transfer of the reacting organic group located mostly in an apical position on silicon to the transition metal would proceed. It can reasonably be inferred that rather electron ─ withdrawing alkenyl and aryl groups on the silicon center prefer to occupy an apical position of the postulated pentacoordinate silicates (Mutterties’ rule).

Scheme 13. General catalytic cycle of cross ─ coupling reaction using 2 ─ (hydroxymethyl)phenyl ─ substituted and related organosilicon reagents.

Table 11. Cross ─ coupling reaction of secondary ─ alkylsilanes 5 with aryl bromides.

7． Conclusions We have invented 2 ─ (hydroxymethyl)phenyl ─ substituted and related organosilicon reagents that efciently undergo the palladium ─ and nickel ─ catalyzed cross ─ coupling reactions. These tetraorganosilicon reagents have many advantages over various other organometallic reagents used in cross ─ coupling chemistry in terms of easy preparation, fair stability, and recy- clability. Moreover, the newly developed reaction conditions for the cross ─ coupling without use of highly nucleophilic uoride or hydroxide activators but with mild carbonate or phos- phate bases allow for highly chemoselective coupling of vari- ously functionalized alkenyl, aryl, and alkyl groups with a number of organic electrophiles including inexpensive aryl chlorides and tosylates. The formation of cyclic silyl ethers as a readily recoverable and reusable silicon residues is denitely a supremely useful feature of this process, making it particularly

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有機合成化学69-11＿05論文_Nakao.indd 34 2011/10/20 11:15:38 attractive for industrial large scale applications. This issue of 17） Chandra, G.; Lo, P. Y.; Hitchcock, P. B.; Lappert, M. F. Organometal- ready reusability of stoichiometric metal residues has not pre- lics 1987, 6, 191. 18） Trost, B. M.; Ball, Z. T. J. Am. Chem. Soc. 2005, 127, 17644. viously been addressed by other cross ─ coupling protocols. 19） Tamao, K.; Nakagawa, Y.; Arai, H.; Higuchi, N.; Ito, Y. J. Am. Chem. Thus these novel tetraorganosilicon reagents will nd many Soc. 1988, 110, 3712. opportunities for employment in both academia and industry 20） Hatanaka, Y.; Goda, K. ─ i.; Hiyama, T. J. Organomet. Chem. 1994, for synthesis and manufacture of target substances. 33 465, 97. 21） Shirakawa, E.; Yoshida, H.; Takaya, H. Tetrahedron Lett. 1997, 38, 3759. Acknowledgement 22） Milne, J. E.; Buchwald, S. L. J. Am. Chem. Soc. 2004, 126, 13028. We deeply acknowledge our coworkers Akhila K, Sahoo 23） Littke, A. In Modern Arylation Methods; Ackermann, L., Ed.; Wiley ─ VCH: Weinheim, 2009, pp 25 ─ 67. (post ─ doc), Jinsui Chen (Ph.D.), Akira Yada (Ph.D.), 24） Shimizu, M.; Schelper, M.; Mochida, K.; Hiyama, T.; Adachi, M.; Hidekazu Imanaka, Shiro Ebata, Masaaki Tanaka, Masahide Sasaki, Y.; Akiyama, S.; Maeda, S.; Kanbara, H.; Mori, Y.; Kurihara, Takeda, and Takuya Matsumoto for their extensive contribu- T. Adv. Mater. 2007, 19, 1826. tions to exploitation of the present work. This work has been 25） For the Suzuki ─ Miyaura cross ─ coupling of arylmethyl carbonates: Kuwano, R.; Yokogi, M. Org. Lett. 2005, 7, 945. supported nancially by a Grant ─ in ─ Aid for Creative Scientic 26） (a) Guibe, F.; M’leux, Y. S. Tetrahedron Lett. 1981, 22, 3591. (b) Tsuji, Research (No. 16GS0209) and for Priority Areas “Synergy of J.; Shimizu, I.; Minami, I.; Ohashi, Y.; Sugiura, T.; Takahashi, K. J. Elements” (Nos. 19027029 and 20036030) from MEXT. Org. Chem. 1985, 50, 1523. 27） Matsuhashi, H.; Asai, S.; Hirabayashi, K.; Hatanaka, Y.; Mori, A.; Hiyama, T. Bull. Chem. Soc. Jpn. 1997, 70, 437. References 28） Kataoka, N.; Shelby, Q.; Stambuli, J. P.; Hartwig, J. F. J. Org. Chem. 1） (a) Metal ─ Catalyzed Cross ─ Coupling Reactions; de Meijere, A.; 2002, 67, 5553. Diederich, F., Eds.; Willey ─ VCH: Weinheim, 1998. (b) Metal ─ Cata- 29） Rauf, W; Brown, J. M. Angew. Chem. Int. Ed. 2008, 47, 4228. lyzed Cross ─ Coupling Reactions, 2nd ed.; de Meijere, A.; Diederich, F., 30） Hayashi, T.; Konishi, M.; Kobori, Y.; Kumada, M.; Higuchi, T.; Eds.; Willey ─ VCH: Weinheim, 2004. Hirotsu, K. J. Am. Chem. Soc. 1984, 106, 158. 2） Pentauoro(organo)silicates were reported to undergo palladium ─ cat- 31） Hatanaka, Y.; Ebina, Y.; Hiyama, T. J. Am. Chem. Soc. 1991, 113, alyzed cross ─ coupling reactins for limited examples: Yoshida, J.; 7075. Tamao, K.; Yamamoto, H.; Kakui, T.; Uchida, T.; Kumada, M. 32） Nakao, Y.; Chen, J.; Imanaka, H.; Hiyama, T.; Ichikawa, Y.; Duan, W. Organometallics 1982, 1, 542. L.; Shintani, R.; Hayashi, T. J. Am. Chem. Soc. 2007, 129, 9137. 3） (a) Hatanaka, Y.; Hiyama, T. J. Org. Chem. 1988, 53, 918. For the 33） (Hydroxymethyl)phenyl ─ substituted silicon reagents (HOMSi reaction mechanism by theoretical calculations, see: (b) Sugiyama, A.; reagents) are commercially available worldwide from Advanced Ohnishi, Y. ─ y.; Nakaoka, M.; Nakao, Y.; Sato, H.; Sakaki, S.; Nakao, Molecular Technologies Pty Ltd. and domestically from Wako Pure Y.; Hiyama, T. J. Am. Chem. Soc. 2008, 130, 12975. Chemical Industries, Ltd. 4） (a) Hiyama, T.; Shirakawa, E. Top. Curr. Chem. 2002, 219, 61. (b) Denmark, S. E.; Sweis, R. F. In Metal ─ Catalyzed Cross ─ Coupling Reactions, 2nd ed.; de Meijere, A.; Diederich, F., Eds.; Willey ─ VCH: Weinheim, p 163, 2004. (c) Tsuji, J. Palladium Reagents and Catalysts; Wiley: Chichester, p 338, 2004. 5） Denmark, S. E.; Choi, J. Y. J. Am. Chem. Soc. 1999, 121, 5821. 6） (a) Itami, K.; Nokami, T.; Yoshida, J. ─ i. J. Am. Chem. Soc. 2001, 123, 5600. (b) Hosoi, K.; Nozaki, K.; Hiyama, T. Proc. Japan Acad. Ser. B 2002, 78, 154. (c) Katayama, H.; Taniguchi, K.; Kobayashi, M.; Sagawa, T.; Minami, T.; Ozawa, F. J. Organomet. Chem. 2002, 645, 192. (d) Anderson, J. C.; Munday, R. H. J. Org. Chem. 2005, 69, 8971. 7） Trost, B. M.; Machacek, M. R.; Ball, Z. T. Org. Lett. 2003, 5, 1895. 8） Sahoo, A. K.; Oda, T.; Nakao, Y.; Hiyama, T. Adv. Synth. Catal. 2004, 346, 1715. 9） (a) Denmark, S. E.; Kallemeyn, J. M. J. Am. Chem. Soc. 2006, 128, 15958. (b) Denmark, S. E.; Smith, R. C.; Tymonko, S. A. Tetrahedron 2007, 63, 5730. (c) Denmark, S. E.; Baird, J. D.; Regens, C. S. J. Org. Chem. 2008, 73, 1440. (d) Denmark, S. E.; Werner, N. S. J. Am. Chem. Soc. 2008, 130, 16382. (e) Denmark, S. E.; Smith, R. C.; Chang, W. T. T.; Muhuhi, J. M. J. Am. Chem. Soc. 2009, 131, 3104. 10） Brook, A. G. Acc. Chem. Res. 1974, 7, 77. 11） (a) Taguchi, H.; Ghoroku, K.; Tadaki, M.; Tsubouchi, A.; Takeda, T. J. Org. Chem. 2002, 67, 8450. (b) Taguchi, H.; Takami, K.; Tsubouchi, A.; Takeda, T. Tetrahedron Lett. 2004, 45, 429. 12） Shindo, M.; Matsumoto, K.; Shishido, K. Synlett 2005, 176. 13） (a) Hudrlik, P. F.; Abdallah, Y. M.; Hudrlik, A. M. Tetrahedron Lett. 1992, 33, 6747. (b) Hudrlik, P. F.; Arango, J. O.; Hijji, Y. M.; Okoro, C. O.; Hudrlik, A. M. Can. J. Chem. 2000, 78, 1421. 14） (a) Nakao, Y.; Imanaka, H.; Sahoo, A. K.; Yada, A.; Hiyama, T. J. Am. Chem. Soc. 2005, 127, 6952. (b) Nakao, Y.; Sahoo, A. K.; Yada, A.; Chen, J.; Hiyama, T. Sci. Technol. Adv. Mater. 2006, 7, 536. (c) Nakao, Y.; Imanaka, H.; Chen, J.; Yada, A.; Hiyama, T. J. Organomet. Chem. 2007, 692, 585. (d) Nakao, Y.; Chen, J.; Tanaka, M.; Hiyama, T. J. Am. Chem. Soc. 2007, 129, 11694. (e) Chen, J.; Tanaka, M.; Takeda, M.; Sahoo, A. K.; Yada, A.; Nakao, Y.; Hiyama, T. Bull. Chem. Soc. Jpn. 2010, 83, 554. (f) Nakao, Y.; Takeda, M.; Matsumoto, T.; Hiyama, T. Angew. Chem. Int. Ed. 2010, 49, 4447. 15） Nakao, Y.; Ebata, S.; Chen, J.; Imanaka, H.; Hiyama, T. Chem. Lett. 2007, 36, 606. 16） (a) Hiyama, T.; Kusumoto, T. In Comprehensive Organic Chemistry Vol. 8; Trost, B. M.; Fleming, I., Pergamon: Oxford, 1991, p 763. (b) Trost, B. M.; Ball, Z. T. Synthesis 2005, 853.

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有機合成化学69-11＿05論文_Nakao.indd 35 2011/10/20 11:15:39 PROFILE

Yoshiaki Nakao (born in 1976) was educated in chemistry at Kyoto University (Ph.D. with Profs. Tamejiro Hiyama and Eiji Shirakawa), Yale University (visiting student with Prof. John F. Hartwig), and Max ─ Planck ─ Institut für Kohlenforschung (visiting scholar with Prof. Manfred T. Reetz). From 2002 to 2010, he worked with Prof. Hiyama as an assistant professor at Kyoto University. Last year, he was promoted to Lecturer at Kyoto Universi- ty. He received Mitsui Chemicals Catalysis Science Award of Encouragement (2009), The Society of Silicon Chemistry Award of Encouragement (2009), Thieme Journal Award (2010), Merck ─ Banyu Lectureship Award (2010), The Chemical Society of Ja- pan Award for Young Chemists (2011), and The Commendation for Science and Technol- ogy by MEXT, The Young Scientists’ Prize (2011). His research interests include the development of new synthetic reactions by metal catalysis for selective organic synthesis.

Tamejiro Hiyama was appointed to be associ- ate professor at Kyoto University in 1972, completed his Ph.D. in engineering at Kyoto University in 1975 right before he spent a postdoctoral year at Harvard University. In 1981 he started his own independent research at the Sagami Chemical Research Center. In 1992 he moved to the Research Laboratory for Resources Utilization, Tokyo Institute of Technology, as a full professor and further to Graduate School of Engineering, Kyoto University, in 1997. Since retirement from Kyoto University in 2010, he has been at Chuo University as RDI Professor. His research covers areas from novel synthetic methods (Hiyama reaction, Hiyama cross ─ coupling, Nozaki ─ Hiyama ─ Kishi reaction, Oxidative Desulfurization Fluorination, etc) to the synthesis of biologically active substances and invention of novel functional materials like liquid crystals and organic light emitting materials.

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