Expedient synthesis of β,β-disubstituted α-methylenepropionates

Abstract

Baylis–Hillman alcohols are excellent sources of the allylic halides ArCH CH(CH 2X)(CO 2R) (X=Br, Cl; R 1=Me, Et, Bu t ). The Z double bond isomers are attained in high isomeric purity (>14:1, Z/ E). The halides are chemo- and regiospecifically transformed into the acrylates (ArCHR 2)C( CH 2)(CO 2R 1) on treatment with Zn(R 2) 2 (R 2=Me, Et, CH 2TMS, CH 2SiMe 2OMe) or PrZnBr in the presence of catalytic amounts of copper(I) salts (0.5–20 mol%) in high yield.