Diastereoselective Synthesis of Stable Phosphorus Ylides by a Three-Component Reaction between Triphenylphosphine,Dialkyl Acetylenedicarboxylates and 3-(Arylsulfonylhydrazono)Butanoates

Protonation of the reactive 1:1 intermediate produced in the reaction between dialkyl acetylenedicarboxylates and triphenylphosphine by 3-(arylsulfonylhydrazono)butanoates leads to vinylphosphonium salts which undergo Michael addition with the conjugate base of the CH-acid to produce highly functionalised, salt-free phosphorus ylides in a diastereoselective manner and excellent yields.