Improved <i>E</i>-Selectivity in the Wittig Reaction of Stabilized Ylides with α-Alkoxyaldehydes and Sugar Lactols
作者:Christian Harcken、Stephen F. Martin
DOI:10.1021/ol016729+
日期:2001.11.1
[GRAPHICS]The Wittig reactions of alpha -alkoxyaldehydes and sugar lactols with stabilized ylides such as (alkoxycarbonylmethylene)triphenylphosphoranes typically proceed with low E-selectivities. However, we have discovered that the reaction of such aldehydes with (methoxycarbonylmethylene)tributylphosphorane in toluene in the presence of catalytic amounts of benzoic acid proceeds to give the E-alpha,beta -unsaturated esters with high selectivities and in high yields.