Acid-Mediated Highly Regioselective Oxidation of Substituted Furans: A Simple and Direct Entry to Substituted Butenolides

4 pages, 2 tables, 3 schemes.The scope and limitations of an expeditious synthesis of substituted butenolides from 3-substituted or 3,4-disubstituted furans is described. The entire process embodies a controlled oxidation of the furan core to a 2,5-dialkoxy-dihydrofuran intermediate and a regioselective acid-catalyzed hydrolysis to the butenolide ­derivative. 3-Substituted furans yield exclusively 2-substituted butenolides. Calculations studies provide substantiation of a proposed mechanism.The authors thank Spanish Ministerio de Educación y Ciencia (PPQ2002-04361-C04-02 and PPQ2002-04361-C04-03), CONICET (Project 2429) and UNSL (Project 7301) for financial support. JPC thanks Universidad de La Laguna for a postdoctoral Intercampus Fellowship