[2 + 4] Annulation of Alkyl(phenyl)phosphinic Chlorides with Enones: Stereoselective Synthesis of δ‑Phosphinolactones

Various δ-phosphinolactones (δ-phostines) are efficiently and diastereospecifically synthesized in good to excellent yields from direct [2 + 4] annulation of alkyl(phenyl)phosphinic chlorides and α,β-enones in the presence of LiHMDS. The annulation involves deprotonation, Michael addition, and nucleophilic substitution and features readily available materials, good to excellent yields, diastereospecificity, atom and step economy, wide substrate scope, easy separation, and mild conditions.