Highly Z -Selective Horner-Wadsworth-Emmons Olefination Using Modified Still-Gennari-Type Reagents.

In this report, new, easily accessible reagents for highly Z -selective HWE reactions are presented. Alkyl di-(1,1,1,3,3,3-hexafluoroisopropyl)phosphonoacetates, structurally similar to Still-Gennari type reagents, were tested in HWE reactions with a series of various aldehydes. Very good Z -selectivity (up to a 98:2 Z : E ratio) was achieved in most cases along with high yields. Application of the new reagents may be a valuable, practical alternative to the well-established Still-Gennari or Ando Z -selective carbonyl group olefination protocols.