Application of the Z-Selective Still–Gennari Olefination Protocol for the Synthesis of Z-α,β-Unsaturated Phosphonates

Abstract

Application of the Z-selective Still–Gennari modification of Horner–Wadsworth–Emmons (HWE) reaction for the olefination of acylphosphonates is presented. A series of new Z-α,β-unsaturated phosphonates containing a carbonyl or ester moiety in the β-position were obtained in up to 94% yield and with up to 96% Z-selectivity. The standard HWE olefination of the acylphosphonates, which was performed for comparison, was either unsuccessful at all, or resulted in an inferior Z-selectivity and lower isolated yields.