Enantioselective Synthesis of 3,4-Dihydroisoquinolin-1(2H)-ones by Nickel-Catalyzed Denitrogenative Annulation of 1,2,3-Benzotriazin-4(3H)-ones with Allenes

A denitrogenative annulation reaction of 1,2,3-benzotriazin-4(3H)-ones with allenes catalyzed by a nickel-phosphine complex to produce a variety of substituted 3,4-dihydroisoquinolin-1(2H)-ones in a regioselective manner is described. A highly enantioselective version, as well as structural evidence for the mechanistic course of this reaction, is also presented.