Copper-Catalyzed Diastereoselective Borylative Allylation of Alkenyl Sulfones and Base-Controlled Synthesis of Skipped Dienes.

Divergent functionalization of α,β-unsaturated sulfones under copper catalysis is reported. Diastereoselective borylative allylation of alkenyl sulfones was achieved with a copper catalyst, allyl phosphate, bis(pinacolato)diboron, and LiOMe. In this method, the addition of a copper-boryl complex to alkenyl sulfone and subsequent allylic substitution rendered boroallylated products in good yield with excellent syn -diastereoselectivity. In contrast, a stronger base (KO t -Bu) promoted the reaction further toward the formation of ( E )-skipped dienes, through elimination of the sulfonyl and boryl groups.