The α-halogenation of α,β-unsaturated carbonyls and dihalogenation of alkenes using bisacetoxyiodobenzene/pyridine hydrohalides

A procedure for the α-chlorination or bromination of a number of α,β-unsaturated carbonyls, and the dichlorination or bromination of alkenes, is developed using bisacetoxyiodobenzene (BAIB) and the HCl or HBr salt of pyridine. The reaction proceeds in an acceptable to a good yield and has a broad substrate scope. The dibromination is also achieved using a chiral I[V] reagent, although little enantioselectivity could be achieved.