Allylboration of Ketones and Imines with a Highly Reactive Bifunctional Allyl Pinacolatoboronate Reagent.

Allylboration of ketones and imines with a bifunctional allylboron reagent is reported. Addition of the bifunctional allylboronate to a broad scope of ketones gave tertiary alcohols in excellent yields at ambient temperature without any catalyst or additive. Allylboration of cyclic aldimines also proceeded to give allylated products in good yields under the same reaction conditions. The allylsilane moiety in the product underwent a second allylation with aldehydes or acetals. As such, the bifunctional allylboron reagent serves as a useful linchpin to join two distinct carbonyl compounds to provide synthetically useful intermediates.