Asymmetric [2,3]-Wittig rearrangement of the dienolates of chiral secondary alcohol-substituted β-pyrrolidinyl-γ-allyloxyl-α,β-unsaturated esters: total synthesis of (+)-eldanolide
作者:Yu-Jang Li、Guo-Ming Ho、Pin-Zu Chen
DOI:10.1016/j.tetasy.2009.07.028
日期:2009.8
The asymmetric [2,3]-Wittig rearrangement of the dienolates of various chiral beta-pyrrolidinyl-gamma-allyloxyl-alpha,beta-unsaturated esters was investigated using different chiral secondary alcohol Substitutions. When (1S,2R,4R)-2-hydroxy-7,7-dimethylbicyclo[2,2,1]heptane-1-carboxylic acid diisopropylamide was used as chiral auxiliary, it provided the best enantioselectivity in the rearrangement. When various gamma-allyloxy substitutions underwent temperature and additive studies, 1,1-dimethylpropenoxy substitution was found to give the best enantioselectivity. The methodology was applied to the total synthesis of eldanolide. (C) 2009 Elsevier Ltd. All rights reserved.