Selenium-Catalyzed Regioselective Cyclization of Unsaturated Carboxylic Acids Using Hypervalent Iodine Oxidants

A new and convenient selenium-catalyzed regioselective cyclization of gamma,delta-unsaturated carboxylic acids to the corresponding 3,6-dihydro-2H-pyran-2-ones is described. The cyclization products have been obtained in good to excellent yields using diphenyl diselenide as a catalyst and [bis(trifluoroacetoxy)iodo]benzene as a stoichiometric oxidant.