Mukaiyama Michael reaction enolsilanes

Mukaiyama Michael reactions of alkylidene malonates and enolsilanes have also been examined (244). The stoichiometric reaction between enolsilane (342a) and alkylidene malonate (383) proceeds in high selectivity however, catalyst turnover is not observed under these conditions. The addition of HFIP effectively promotes catalyst turnover, presumably by protonation and silyl transfer from the putative copper malonyl enolate generated in this reaction. The reaction proved general for bulky P-substituents (aryl, branched alkyl), Eq. 209. 

A catalytic asymmetric amination reaction has been developed using Cu(2+) catalysts (246). The azodicarboxylate derivative 392 reacts with enolsilanes in the presence of catalyst 269c to provide the adducts in high enantioselectivity, Eq. 213. As observed in the Mukaiyama Michael reactions, alcoholic addends proved competent in increasing the rate of this reaction. Indeed, in the presence of tri-fluoroethanol as additive, the reaction time decreases from 24 to 3 h. 

Silylketene acetals and enolsilanes can also undergo conjugate addition to a,/ -unsaturated carbonyl derivatives. This reaction is referred to as the Mukaiyama-Michael addition and can also be used as a mild and versatile method for C-C bond formation. As shown in Scheme 8-34, in the presence of C2-symmetric Cu(II) Lewis acid 94, asymmetric conjugate addition proceeds readily, giving product with high yield and enantioselectivity.75... 

Other Lewis acid mediated C-C bond forming reactions of silylated C-nucleophiles include the Mukaiyama aldol and Michael additions of enolsilanes ), the related reaction of allylsilanes described by Sakurai ) as well as similar reactions of Me3SiCN ). Other "inert C-nucleophiles such as dialkylzinc compounds also react with carbonyl compounds in the presence of Lewis acids ). We ourselves have utilized many of these processes in performing stereoselective reactions, particularly in achieving diastereofacial selectivity in the reactions... 

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