Synthesis of Alkenyl Boronates from Epoxides with Di-[B(pin)]-methane via Pd-Catalyzed Dehydroboration.

A practical and broadly applicable catalytic method for the synthesis of (E)-alkenylborons is presented. Reactions are promoted by [Pd(Cl)(η3-C3H5)]2 and proceed by the dehydroboration of cyclic borates. Through the use of epoxides and readily available di-B(pin)-methane (pin = pinacolato), a range of allylic alcohol-containing alkenyl boronates, including those that contain a tertiary alcohol, may be prepared in up to 75% yield and >20:1 E/Z.