Platinum-Catalyzed Michael Addition and Cyclization of Tertiary Amines with Nitroolefins by Dehydrogenation of α,β-sp³ C−H Bonds

A mild platinum-catalyzed oxidative dehydrogenation of α,β-C(sp³)−H bonds of tertiary amines in the presence of ambient oxygen is revealed, and the in situ formed enamines subsequently reacting with various nitroolefins resulted in the development of two one-pot synthetic protocols involving Michael addition−elimination and Michael addition−cyclization. By using different functionalized nitroolefins compatible with the current oxidative conditions, two types of structurally divergent products, trisubstituted enamines and chromano[2,3-b]piperidines, could be expediently accessed, respectively.