3-Butyl-1-methylimidazolinium borohydride ([bmim][BH4])—a novel reducing agent for the selective reduction of carbon–carbon double bonds in activated conjugated alkenes

A novel ionic reducing reagent, 3-butyl-1-methylimidazolium borohydride ([bmim][BH4]), was synthesized and successfully used for the selective reduction of carbon–carbon double bonds in conjugated alkenes as well as the α,β-carbon–carbon double bonds in highly activated α,β,γ,δ-unsaturated alkenes. The reagent can be regenerated and reused several times without losing its activity.