Alkenes, reaction with chloroborane

The potassium reagent (1) will deprotonate simple alkenes to give allylic anions. Subsequent reaction with a chloroborane results in the allylic borane, which, in turn, can be converted to an allyl alcohol (eq 4). ... 

Over the past few years, the research groups of Marks and Piers have developed a number of new and effective perfluoroarylborane activators as well as bifunctional boranes. Bis(pentafluorophenyl)bo-rane [HB(CeF5)2]2 was synthesized by Piers et al. by reduction of monomeric chloroborane with Me2-Si(Cl)H (which also serves as the solvent for the reaction) in a quantitative yield. This white, crystalline material exists in a dimeric form in the solid state and in suspension in toluene or benzene promotes rapid hydroboration of a range of simple alkenes and alkynes. The details of the hydroboration chemistry as well as the reaction of the products with zirconocene dialkyls have been the subject of a recent review article. ... 

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