Synthesis of Pharmaceutically Relevant Nitrogen Heterocycles via Rhodium Catalyzed C-H Bond Functionalization

Recently in the Ellman and Bergman groups a method was discovered for preparing 1,2-dihydropyridines via rhodium-catalyzed coupling of α,β-unsaturated imines and alkynes. Subsequent in situ oxidation provides access to the corresponding pyridines. This method was expanded to include terminal alkynes, challenging substrates for transition-metal mediated transformations. In contrast formal reduction of the dihydropyridine intermediates through Diels-Alder reaction with alkenes provides access to isoquinuclidines, an important class of piperidines, in excellent diastereoselectivities