Palladium-Catalyzed Cross-Coupling Reactions of Carboranes with Alkenes via Selective B-H Bond Activation.

A palladium-catalyzed Heck-type cross-coupling reaction of carboranes with alkenes in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was realized. This reaction shows good B(9) selectivity for m-carboranes and is also suitable for o- and p-carborane. Meanwhile, a series of mono-, di-, and trisubstituted alkenes were compatible substrates to afford the alkenylated products in 16-89% yields. The 1,2-bis(carboranyl)ethylene was first synthesized by the reaction of vinyltrimethylsilane and m-carborane. Further transformations of the C═C bond in the product were examined by hydroboration oxidation, oxidation, hydroboration, and bromination reaction to generate corresponding B(9)-functionalized m-carboranes.