Steric influence of silyl groups in titanium- and lithium-mediated aldol condensations
作者:Chitchanun Panyachotipun、Edward R. Thornton
DOI:10.1016/s0040-4039(00)98013-4
日期:——
Reactions of lithium enolates of α-silyloxyketones 1a, 1b, 2a, and 2b with benzaldehyde yield opposite diastereoselection depending upon the size of the silyl group, but all four titanium enolates lead to highdiastereofacialselectivities. These results implicate a nonchelated transition structure which is insensitive to the steric size of the silyl group for the titanium-mediated aldol reactions