A fast, efficient and stereoselective synthesis of hydroxy-pyrrolidines

A five-step, protecting group free synthesis of 2,3-cis substituted hydroxy-pyrrolidines is presented. Key steps in the synthesis are the chemoselective formation of a primary amine via a Vasella reductive amination using ammonia as the nitrogen source, and the stereoselective formation of a cyclic carbamate from an alkenylamine. Improvement of the reductive amination, by way of the use of α-picoline borane as a more environmentally benign reducing agent, is also presented.

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