Synthesis of bis-3,4-dialkoxythiophenes linked by am-xylene bridge

Abstract

Two examples of bis 3,4-dialkoxythiophenes linked with am-xylene bridge were synthesized in yields of18% and 32% in a six step process. The formation of them-xylene bridge, key reaction of the synthesis,was carried out through Williamson, Mitsunobu andtrans-etherification reactions which were subse-quently compared on performance and versatility. The Mitsunobu reaction assisted by sonication wasfound to be the best strategy. These molecules are among the few examples of unsymmetrically substi-tuted 3,4-dialcoxythiophenes. During the synthesis an 18 member heterocycle, closely related to a crownether was isolated. The details of the XRD structure of this heterocycle are discussed.