Regioselective allylzincation of alkenylboronate

[GRAPHICS] Boryl substitution on an olefin activates the olefinic double bond toward a ddition of an organozinc reagent. Addition of an allylic zinc reagent to an alkenylboronate thus takes place smoothly to afford a variety of gem-zinci o/boryl species. Theoretical studies with density functional calculations o n the reaction pathway revealed that the reaction proceeds via a zincio-ene reaction rather than a bora-Claisen rearrangement.