A new visible light-induced method is reported for the C3-alkylation of imidazo[1,2-a]pyrimidines and -pyridines with aryldiazoacetates. This protocol can be performed in open air and serves as a convenient entry to several known and new molecules. A formal synthesis of zolpidem is achieved by changing the alkylating agent to an appropriate hypervalent iodine compound followed by a Krapcho decarboxylation step.

Abstract

This work describes a protocol being only promoted by visible light for the C3-alkylation of imidazo[1,2-a]pyrimidines and imidazo[1,2-a]pyridines with aryldiazoacetates. Several known and new analogs of a key intermediate employed in previous syntheses of zolpidem have been accessed in good yields. The preparation of this key intermediate was also achieved using this method, but an adjustment of the nature of the alkylating agent was required.