Selenium dioxide oxidation of alkylcoumarins and related methyl‐substituted heteroaromatics

Abstract

AbstractBy the use of selenium dioxide as the specific oxidizing agent in the coumarin series, the 4‐ethyl, 4‐propyl and 4‐benzyl substituents of coumarin were converted into α‐alcohols 2 and/or ketones 3, while 3‐methyl‐ and 3‐benzylcoumarins were converted into 3‐acyl derivatives 7. The methyl substituent of the analogous thiocoumarin 5, chromones 10 or thiochromone 11 was also oxidized into the formyl functionality. Facile oxidative desulfurization into the ketone functionality, prior to methyl oxidation, was observed for the thione derivatives of 1a, 5, 6 and 10.