Unusual rapid hydroboration of alkenes using diborane in chlorohydrocarbon solvents

Diborane dissolves in chlorohydrocarbon solvents, such as dichloromethane, 1,2-dichloroethane and 1,1,2,2-tetrachloroethane to form ∼0.5 M solutions of B2H6. In these solutions, diborane is in equilibrium with solvent–BH3 adducts (8–15%) and these solutions hydroborate representative olefins almost instantaneously, even at −16°C. The alcohol products can be obtained by standard oxidation of these organoboranes.