Synthesis of ethynyl phosphonates via enolphosphate intermediates

Abstract

The facile conversions of $\beta$ -keto phosphonates to various-substituted ethynylphosphonates were studied. By the condensation reactions of diethyl methylphosphonate and acyl chlorides with 2-equivalents of n-BuLi base, the $\beta$ -keto phosphonates were prepared conveniently. In one pot processes, these $\beta$ -keto phosphonates were existed as Li-enolate forms, and subsequent phosphorylation to carbonyl oxygen gave the enol phosphates in stereoselective manners. This diethyl phosphate group was easily eliminated to produce the ethynyl phosphonates by tBuOK based. These procedures were proved to be suitable to synthesize the aromaticsubstited ehtynyl phosphonates, particularly.