Two-carbon homologation of ketones via sily ketene acetals: Synthesis of α,β-unsaturated acids and α-trimethylsilyl δ-ketoacids
作者:Moncef Bellassoued、Sinda Mouelhi、Pierre Fromentin、Aurélien Gonzalez
DOI:10.1016/j.jorganchem.2005.01.049
日期:2005.4
O-tris(trimethylsilyl)ketene acetal 1 with saturated, cyclic and aromatic ketones 2 proceeds smoothly in the presence of titanium chloride to give (E)-α,β-unsaturated carboxylic acids 3 with fairly good stereoselectivity. With α,β-unsaturated ketones 4, α-trimethylsilyl δ-ketoacids 5 (syn + anti) are obtained according to Michael-type 1,4 addition. These diastereoisomers are separated and the configurations
C,O,O-三(三甲基甲硅烷基)乙烯酮缩醛1与饱和,环状和芳族酮2的反应在氯化钛存在下平稳进行,得到具有相当好的立体选择性的(E)-α,β-不饱和羧酸3。对于α,β-不饱和酮4,根据迈克尔型1,4加成获得α-三甲基甲硅烷基δ-酮酸5(syn + anti)。分离这些非对映异构体,并通过X射线分子分析获得5a的构型。