Expedient synthesis of β,β-disubstituted α-methylenepropionates

Baylis–Hillman alcohols are excellent sources of the allylic halides ArCHdouble bond; length as m-dashCH(CH2X)(CO2R) (X=Br, Cl; R1=Me, Et, But). 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 (ArCHR2)C(double bond; length as m-dashCH2)(CO2R1) on treatment with Zn(R2)2 (R2=Me, Et, CH2TMS, CH2SiMe2OMe) or PrZnBr in the presence of catalytic amounts of copper(I) salts (0.5–20 mol%) in high yield.