4,5-erythro/5,6-threo-Stereoselectivity in vinylogous Mukaiyama aldol addition of a silyloxypyrrole to a threose derivative: stereochemical rationalization and relevance to (+)-castanospermine synthesis
作者:Roger Hunter、Sophie C.M. Rees-Jones、Hong Su
DOI:10.1016/j.tetlet.2007.02.100
日期:2007.4
Vinylogous Mukaiyama aldol addition of N-p-methoxybenzyl-4-methoxy-2-trimethylsilyloxypyrrole 7 to bis-MOM threose 6 using SnCl4 as promoter gave the 4,5-erythro/5,6-threo adduct 8, with the correct absolute configurations for the castanospermine framework as determined by a single-crystal X-ray structure. A transition-state model is presented to rationalize the stereo selectivity. (c) 2007 Elsevier Ltd. All rights reserved.