In situ formation of alkenyl- and alkynylboranes for Diels—Alder reactions by boron—silicon exchange with alkenyl- and alkynylsilanes
摘要:
A variety of alkenylsilanes underwent transmetallation with BBr3 to afford the corresponding alkenyldibromoboranes in solution. Similarly, the transmetallation of alkynylsilanes with BCl3 afforded alkynyldichloroboranes. A number of the alkenyl- and alkynylboranes are novel and useful Diels-Alder dienophiles. An ionic mechanism for the transmetallation is proposed. (C) 1997 Elsevier Science S.A.