A convenient entry to 5-sp2-substituted and 5,5-disubstituted tetronic acids

3 pages, 1 figure, 1 table, 2 schemes.A one-pot, convenient and general access to 5-sp2-substituted and 5,5-disubstituted tetronic acids is described. The protocol embodies two consecutive chemical events: a Michael addition of pyrrolidine on a secondary or tertiary γ-hydroxy-α,β-alkynyl ester derivative to give the corresponding enamine, and the subsequent acid-catalyzed hydrolysis-lactonization of this intermediate to afford the tetronic acid derivative.This research was supported by the Spanish Ministerio de Educación y Ciencia and the European Regional Development Fund (CTQ2005-09074-C02-02). F.G.T. thanks the Instituto Canario de Investigación del Cáncer for financial support (ICIC-GI nº 10/2005: ISCiii, RTICCC C03/10)