Regioselective Barbier reactions of 2-bromomethylcyclohexenone

Although the addition of crotyl or prenyl organometallic reagents has certainly found application in organic synthesis, the use of other non-symmetric allylic organometallic reagents has not received much attention. In part this is due to potential problems in controlling the regioselectivity of the addition products. We have noted that the tin and zinc reagents derived from 2-bromomethylcyclohexenone afford the complementary α and γ addition products, respectively. These conditions work for the reaction with a range of aldehydes, affording the products in good to modest yield.