Metal-free CH-functionalization of trisubstituted alkenes with pyridinium ylides: Development of the concept

An effective concept for metal-free CH-functionalization of trisubstituted alkenes with pyridinium ylides proceeding via tandem Michael addition/elimination of a pyridine molecule has been proposed. A new series of CH-functionalization products were synthesized via the reaction of <i>in situ</i> generated pyridinium ylides with thiazolones and selenazolones containing an exocyclic double bond substituted by an alkoxycarbonyl group in moderate to excellent yields and high diastereoselectivity.