Au(I)-Catalyzed Synthesis of Trisubstituted Indolizines from 2-Propargyloxypyridines and Methyl Ketones.

A new Au(I)-catalyzed method for the preparation of trisubstituted indolizines from easily accessible 2-propargyloxy-pyridines is reported. The reaction tolerates a wide range of functionality, allowing for diversity to be introduced in four distinct regions of the product (R, R1, R2, and Ar). The proposed mechanism proceeds via enol addition to an allenamide intermediate and explains the observed increase in yields when electron poor methyl ketones are utilized.