HighlyCis-Selective Horner-Wadsworth-Emmons (HWE) Reaction of Methyl Bis(2,4-Difluorophenyl) Phosphonoacetate
摘要:
Of the previously reported Horner-Wadsworth-Emmons (HWE) reaction, the olefination of methyl bis(2,4-difluorophenyl)phosphonoacetate (la) with various aldehydes gave unsaturated esters in the highest cis-selectivity.
A facile two-step synthesis of methyl bis(2,2,2-trifluoroethyl)phosphonoacetate (Still–Gennari reagent) has been developed by exploiting Garegg–Samuelsson reaction conditions. Starting from trimethyl phosphonoacetate, Still–Gennari reagent was prepared in 94% yield via methyl 2-bis[(trimethylsilyl)oxy]phosphoryl}acetate intermediate. This synthetic procedure was also used to prepare some kinds of