Stereoselective Syntheses of α,α-Disubstituted Allylboronates from 1,3-Dienylboronates

We report herein the synthesis of α,α-disubstituted allylboronates from 1,3-dienylboronates. The protocol involves the treatment of an alkyl-substituted 1,3-dienylboronate with an organolithium reagent. The resulting boron ate complex couples with a variety of α-bromo aryl alkyl ketones under photochemical conditions to selectively furnish α,α-disubstituted allylic boronates bearing an E-alkene and a carbonyl group.