Stereoselective dibromination of diphenylphosphorylallenes with N-bromosuccinimide under mild conditions

A highly stereoselective dibromination of diphenylphosphorylallenes using N-bromosuccinimide (NBS) as bromine reagent is developed, wherein a variety of 2-bromo-substituted allyl bromides were obtained in good to excellent yields under mild reaction conditions. Moreover, the dibromination reaction allows a gram-scale synthesis of 2-bromo-substituted allyl bromides, and the products could be successfully transformed to various valuable derivatives.