The mechanism of the Horner–Emmons modification of the Wittig reaction

Abstract

The decomposition of erythro- and threo-β-hydroxyphosphonates in basic medium shows that they partly revert to benzaldehyde and the anion (1) to an extent which is solvent-dependent, and partly inter-convert directly; the ratios of cis- to trans-cinnamonitrile formed from the two β-hydroxyphosphonates are very similar.