Utility of Bifunctional <i>N</i>‑Heterocyclic Phosphine (NHP)-Thioureas for Metal-Free Carbon–Phosphorus Bond Construction toward Regio- and Stereoselective Formation of Vinylphosphonates

An efficient and practical protocol for completely regioselective and highly stereoselective synthesis of vinyldiazaphosphonates from N-heterocyclic phosphine (NHP) and allenes via phospha-Michael/intramolecular nucleophilic substitution reaction has been developed. This transformation enabled the synthesis of valuable densely functionalized vinyldiazaphosphonates with a β-, γ-unsaturated ester moiety under mild reaction conditions. Synthetic utility of vinyldiazaphosphonates was demonstrated by a series of synthetic manipulations.