Collect. Czech. Chem. Commun. 1986, 51, 1685-1691

Preparation and reactions of thieno[3,2-b]furan derivatives

Eva Kraľovičová, Alžbeta Krutošíková and Jaroslav Kováč

Department of Organic Chemistry, Faculty of Chemical Technology, Slovak Institute of Technology, 812 37 Bratislava


Reactions of 3-(5-aryl-2-furyl)propenoic, 3-(2-benzo[b]furyl)propenoic and 3-(5-ethoxycarbonyl-4H-furo[3,2-b]-2-pyrrolyl)propenoic acids with thionyl chloride in the presence of triethylbenzylammonium chloride were investigated. The obtained 2-arylthieno[3,2-b]-furan-5-carboxylic acid chlorides Ia - Ic and 3-chlorothieno[3,2-b]benzo[b]furan-2-carboxylic acid chloride afforded in substitution nucleophilic reactions the corresponding esters V and carboxylic acids VI which were decarboxylated to VII. 3-Chlorothieno[3,2-b]benzo[b]furan-2-carboxylic acid chloride (Id), 6-ethoxycarbonyl-3-chlorothieno[2',3':4,5]furo[3,2-b]pyrrole-2-carboxylic acid chloride (IV), and ethyl 3-chlorothieno[2',3':4,5]furo[3,2-b]indole-2-carboxylate (VIII), synthesized under conditions of triethylphosphite reduction from ethyl 6-chloro-2-(2-nitrophenyl)thieno[3,2-b]furan-5-carboxylate (Va), are new heterocyclic systems.