DIPROTODECARBOXYLATION REACTIONS OF 3,4-DIALKOXYTHIOPHENE-2,5-DICARBOXYLIC ACIDS MEDIATED BY Ag 2 CO 3 AND MICROWAVES Pablo A. Cisneros-Pe ´rez, Diego Martı ´nez-Otero, Erick Cuevas-Ya ´nez, and Bernardo A. Uribe-Frontana Centro Conjunto de Investigacio ´n en Quı ´mica Sustentable, UAEM-UNAM, Toluca, Estado de Me ´xico, Mexico GRAPHICAL ABSTRACT Abstract An efficient and rapid method is reported to obtain 3,4-dialkoxythiophenes from 3,4-dialkoxythiophene-2,5-dicarboxylic acids through a diprotodecarboxylation reaction with Ag 2 CO 3 /AcOH as a catalytic system and microwave heating in dimethylsulfoxide (DMSO) as solvent. This methodology lets us obtain for the first time good performance with thiophenes bearing strong electron-donating groups such as alkoxides. This methodology eliminates the usage of harmful quinoline as solvent, as well as the long reaction times typically used (12– 18 h) to obtain the 3,4-dialkoxythiophenes. The reaction of 7 diacids showed good yields (60–89%) following 20 min of microwave heating in a temperature range of 120–150  C. [Supplementary materials are available for this article. Go to the publisher’s online edition of Synthetic Communications 1 for the following free supplemental resource(s): Full experimental and spectral details.] Keywords Ag 2 CO 3 ; 3,4-dialkoxythiophene-2,5-dicarboxylic 3,4-dialkoxythiophenes; mic- rowaves; protodecarboxylation INTRODUCTION 3,4-Dialkoxythiophenes are very important substances in the preparation of oligothiophenes and polythiophenes, [1] which have interesting electronic properties and find applications in electronic devices fabrication, as organic light-emitting diodes (OLEDs) [2a] and organic field-effect transistors (OFETs), [2b] electrochromic materials, [2c] biosensors, [2d] chemosensors, [2e] organic solar cells, [2f] etc. One of the Received April 4, 2013. Address correspondence to Bernardo A. Uribe-Frontana, Centro Conjunto de Investigacio ´n en Quı ´mica Sustentable, UAEM-UNAM, Carretera Toluca-Atlacomulco Km 14.5, Campus UAEMe ´x ‘‘San Cayetano’’ Toluca, C.P. 50200, Estado de Me ´xico, Mexico. E-mail: bafrontu@unam.mx Synthetic Communications 1 , 44: 222–230, 2014 Copyright # Taylor & Francis Group, LLC ISSN: 0039-7911 print=1532-2432 online DOI: 10.1080/00397911.2013.800212 222 Downloaded by [UNAM Ciudad Universitaria] at 17:02 14 November 2013