Pyridine-N-Oxide as a Mild Reoxidant Which Transforms Osmium-Catalyzed Oxidative Cyclization

摘要

Recent reports from our group showed that the catalytic oxidative cyclization of 1,5-dienes111 directly to cis tetrahy-drofurans (THFs) can be interrupted and that vicinal diols derived from 1,5-dienes also cyclize to give THF rings in excellent yields under the action of osmium tetroxide and an acid.In addition,we also disclosed that the corresponding N-tosyl amino alcohols (tosyl =p-toluenesulfonyl) bearing a pendant alkene cyclize to give the relevant pyrrolidine ring systems 2,the first time that such oxidative methodology had been used to form nitrogen heterocycles (Scheme l).