Synthetic studies toward paraherquamides E and F and related 13C-labeled putative biosynthetic intermediates: stereocontrolled synthesis of the α-alkyl-β-methylproline ring system
作者:Konrad Sommer、Robert M. Williams
DOI:10.1016/j.tet.2008.05.068
日期:2008.7
putative biosynthesis intermediates have been prepared efficiently in six steps and 24% overall yield. The key steps are a 5-exo-trig cyclization of a zinc enolate on an unactivated alkene and a stereocontrolled alkylation of the enolate formed from 3S-methyl-pyrrolidine-1,2R-dicarboxylic acid 1-tert-butyl ester 2-ethyl ester.
取代的 2R-烯丙基-3S-甲基脯氨酸乙酯适用于制备对羟基苯甲酰胺 E、F 和相关 (13) C 标记的推定生物合成中间体,已通过六个步骤高效制备,总产率为 24%。关键步骤是烯醇锌在未活化烯烃上的 5-exo-trig 环化和由 3S-甲基-吡咯烷-1,2R-二羧酸 1-叔丁酯 2-乙酯形成的烯醇的立体控制烷基化.