Rhodium-Catalyzed Hydrocarbonylation of a Homoallylamine via N-H Activation and Application for Synthesis of Yohimbane Alkaloids

We describe syntheses of n-yohimbane and alloyohimbane using Rh-catalyzed hydrocarbonylation, which provides a practical methodology to synthesize a delta-lactam from a secondary homoallyl amine. We have also observed an unexpected transformation where the amine proton served as a hydride to participate in hydrocarbonylation. The D-labeled experimental results and preliminary DFT-calculations suggest that the transformation can be rationalized by oxidative cleavage of the homoallyl amines to a metal hydride complex.