Quantum Chemical Calculations on the Peterson Olefination with α-Silyl Ester Enolates
摘要:
The reaction of stabilized Peterson reagents (alpha-silyl ester enolates) with ketones has been studied theoretically and experimentally. Enolate geometry was studied by trapping experiments and NMR spectroscopy and was found to differ markedly with the nature of the base (LiHMDS vs LDA vs KHMDS), The chelating effect of the lithium counterion was found to be critical for the reaction. For the two ketones studied, the combined weight of experimental and computational data assigns geometrical selectivity to the initial addition transition state, though in general there appears to be a fine balance between three possible choices for the rate-determining step.
Stereocontrolled synthesis of α,β-unsaturated carboxylic esters from O-methyl-C,O-bis(trimethylsilyl)ketene acetal and aliphatic aldehydes
作者:Isamu Matsuda、Yusuke lzumi
DOI:10.1016/s0040-4039(01)90445-9
日期:1981.1
(R*,S*) Selective aldol type reaction of O-methyl-C,O-bis(trimethylsilyl)ketene acetal () with aldehydes and stereoselective formation of α,β-unsaturatedcarboxylicesters are attained by the combination of Z- and Lewis acids.