Hydroboration. 77. Revision of the Regioselectivity of the Hydroboration of Alkenes with Dihaloborane-Dimethyl Sulfide Complexes

Article abstract of DOI:10.1021/jo00356a028

The hydroboration of alkanes with dihaloborane-dimethyl sulfide complexes (HBX2*SMe2, X = Cl, Br, and I) was systematically reexamined to establish the true regioselectivities in hydroboration with these reagents.Hydrogen halides (HX, X = Cl, Br, and I) liberated during the hydrolysis-oxidation of the alkyldihaloborane-dimethyl sulfide complexes (RBX2*SMe2) add to the residual alkene and hydrolyze to alcohols, thus introducing a significant error in the regioselectivity of such hydroborations.The true regioselectivities in the hydroboration of alkenes with HBX2*SMe2 reveal considerably smaller formation of secondary and tertiary derivatives than previously reported, a result that should significantly enhance the value of these hydroborating agents.