Highly selective enolization method for heteroatom substituted esters; its application to the ireland ester enolate claisen rearrangement
作者:Kouji Hattori、Hisashi Yamamoto
DOI:10.1016/s0040-4020(01)81109-1
日期:1994.3
A method for the stereoselective synthesis of silyl ketene acetals from α-siloxy esters, β-hydroxy esters, and α-amino esters is described. Internal quench with excess trimethylsilyl chloride of the lithium enolate at −100 °C, which is generated using a hindered base, LTMP, leads to the selective formation of E-silyl ketene acetal. In contrast, the deprotonation at −100 °C using LHMDS in THF-HMPA (4:1)
描述了一种由α-甲硅烷氧基酯,β-羟基酯和α-氨基酯立体选择性合成甲硅烷基烯酮缩醛的方法。使用受阻碱LTMP在-100°C下用过量的烯醇锂的三甲基甲硅烷基氯进行内部淬灭,可选择性地形成E-甲硅烷基乙烯酮缩醛。相反,使用LHMDS在THF-HMPA(4:1)中在-100°C进行去质子化,然后用叔丁基二甲基甲硅烷基氯进行处理,可以选择性地得到Z-甲硅烷基烯酮缩醛。该方法可用于爱尔兰酯烯酸酯克莱森重排的立体选择反应。