Tamao reaction

Reactivity of benzo[l,2]oxasilole 21 was also studied <2004GC122>. Homoallylic alcohol 22 was obtained by treatment with tetrabutylammonium fluoride (TBAF). Tamao reaction provided the desilylated ortho-phcnoXxc benzyl alcohol 23. Finally, treatment with methyllithium resulted in nucleophilic methylation on silicon and opening of the Si-O bond (Scheme 3). 

Magar, S. S., Fuchs, P. L. Synthesis of tertiary alcohols via the use of the allyidimethylsilyl moiety as a latent hydroxyl group in the Kumada-Fleming-Tamao reaction. Tetrahedron Lett. 1991,32, 7513-7516. 

Substitution Reactions Involving Organomagnesium Derivatives (the Kumada-Corriu-Tamao Reaction)... 

The cyclohexyloxy(dimethyl)silyl unit in 8 serves as a hydroxy surrogate and is converted into an alcohol via the Tamao oxidation after the allylboration reaction. The allylsilane products of asymmetric allylboration reactions of the dimethylphenylsilyl reagent 7 are readily converted into optically active 2-butene-l, 4-diols via epoxidation with dimethyl dioxirane followed by acid-catalyzed Peterson elimination of the intermediate epoxysilane. Although several chiral (Z)-y-alkoxyallylboron reagents were described in Section 1.3.3.3.3.1.4., relatively few applications in double asymmetric reactions with chiral aldehydes have been reported. One notable example involves the matched double asymmetric reaction of the diisopinocampheyl [(Z)-methoxy-2-propenyl]boron reagent with a chiral x/ -dialkoxyaldehyde87. 

Tamao K, Miyaura N (2002) Introduction to Cross-Coupling Reactions. 219 1-9... 

Tamao K, Miyaura N (2002) Introduction to Cross-Coupling Reactions. 219 1-9 Tanaka M (2003) Homogeneous Catalysis for H-P Bond Addition Reactions. 232 25-54 Tanner PA (2004) Spectra, Energy Levels and Energy Transfer in High Symmetry Lanthanide Compounds. 241 167-278 ten Cate MGJ, see Crego-Calama M (2005) 249 in press ten Holte P,see Zwanenburg B (2001) 216 93-124 Thiem J,see Werschkun B (2001) 215 293-325... 

Leighton and coworkers [217] have also used this approach to develop efficient strategies for the synthesis of polyketide-derived natural products [218]. A main motif of these compounds is a skipped polyol structure, as in 6/2-94 this can easily be prepared by a novel Rh-catalyzed domino reaction of a diallylsilyl ether in the presence of CO, followed by a Tamao oxidation [219]. Thus, reaction of, for example, the silane 6/2-93, which is readily prepared from the corresponding ho-... 

Type I and II silicon-tethered carbonyl-ene reactions were first performed by Robertson.4,4a,4b One particularly striking application of this method is the conversion of isoserine derivative 3 (Scheme 1) into amino triol 4 via a carbonyl-ene reaction followed by Tamao-Fleming oxidation.5... 

Palladium-catalyzed bis-silylation of methyl vinyl ketone proceeds in a 1,4-fashion, leading to the formation of a silyl enol ether (Equation (47)).121 1,4-Bis-silylation of a wide variety of enones bearing /3-substituents has become possible by the use of unsymmetrical disilanes, such as 1,1-dichloro-l-phenyltrimethyldisilane and 1,1,1-trichloro-trimethyldisilane (Scheme 28).129 The trimethylsilyl enol ethers obtained by the 1,4-bis-silylation are treated with methyllithium, generating lithium enolates, which in turn are reacted with electrophiles. The a-substituted-/3-silyl ketones, thus obtained, are subjected to Tamao oxidation conditions, leading to the formation of /3-hydroxy ketones. This 1,4-bis-silylation reaction has been extended to the asymmetric synthesis of optically active /3-hydroxy ketones (Scheme 29).130 The key to the success of the asymmetric bis-silylation is to use BINAP as the chiral ligand on palladium. Enantiomeric excesses ranging from 74% to 92% have been attained in the 1,4-bis-silylation. 

Coupling reactions of non-conjugated a,o>diynes have been systematically classified by Tamao [17]. 

Scheme 10.5. System for different coupling reactions of non-conjugated diynes proposed by K. Tamao [1 7].

Recently, Schaumann et al. 153,154 an(j Bienz et tf/.155,156 have developed dependable routes for the resolution of racemic functionalized organosilanes with Si-centered chirality using chiral auxiliaries, such as binaphthol (BINOL), 2-aminobutanol, and phenylethane-l,2-diol (Scheme 2). For instance, the successive reaction of BINOL with butyllithium and the chiral triorganochlorosilanes RPhMeSiCl (R = /-Pr, -Bu, /-Bu) affords the BINOL monosilyl ethers 9-11, which can be resolved into the pure enantiomers (A)-9-ll and (7 )-9-11, respectively. Reduction with LiAlFF produces the enantiomerically pure triorgano-H-silanes (A)- and (R)-RPhMeSiH (12, R = /-Pr 13, -Bu 14, /-Bu), respectively (Scheme 2). Tamao et al. have used chiral amines to prepare optically active organosilanes.157... 

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