A green procedure for the regio- and chemoselective hydrophosphonylation of unsaturated systems using CaO under solventless conditions

Diethyl phosphite and diphenylphosphine add to a series of unsaturated derivatives using environmentally-friendly calcium oxide as a basic promoter under solventless conditions at room temperature. The corresponding adducts are obtained in a totally regioselective fashion, via a 1,4-addition on alpha,beta-unsaturated esters and sulfone, and a 1,2-addition on cyclic and acyclic alpha,beta-unsaturated aldehydes and ketones.