A 1,3,2-Diazaphospholene-Catalyzed Reductive Claisen Rearrangement

1,3,2-Diazaphospholenes (DAPs) are an emerging class of organic hydrides. In this work, we exploited them as efficient catalysts for very mild reductive Claisen rearrangements. The method is tolerant towards a wide variety of functional groups and operates at ambient temperature. Besides being enantiospecific for substrates with existing stereogenic centers, the diastereoselectivity can be switched by varying solvents and DAP catalysts. The reaction kinetics show direct rearrangements of O-bound phospholene enolates and provide a proof-of-principle for catalytic enantioselective reactions.