Allylic Phosphorus Ylides Directly Generated from Alcohols with Water as the Only Byproduct.

A novel strategy for the preparation of allylic phosphorus ylides directly from Morita-Baylis-Hillman (MBH) alcohols in an environmentally benign manner was developed. With the assistance of a calcium catalyst, the SN2' process between phosphines and allylic alcohols occurred smoothly, delivering allylic phosphorus salts and calcium-stabilized hydroxide ions. Then, in situ deprotonation gave the allylic phosphorus ylides with water as the only byproduct. Functionalized 1,3-diene moieties can be conveniently obtained by trapping the ylides through a Wittig olefination.