Síntese de calcogenofenos, benzo[b]calcogenofenos e benzo[b]furanos utilizando Oxone®

Abstract

This work describes the aplication of the system containing Oxone® and ethanol in the synthesis of new 2,3 bis(organochalcogenyl)benzo[b]chalcogenophenes and -benzo[b]furans. The synthesis involves an eletrophilic cyclization reaction between diorganyl dichalcogenides and 2-thiopropyl-chalcogenoalkynes (11 examples; 46% to 95% yield), 2-methoxy-chalcogenoalkynes (7 examples; 42% to 89% yield) and 2 selenobutyl-selenoalkynes (4 examples; 71% to 94% yield). Subsequently, the Oxone®/diorganoyl dichalcogenide/ethanol system was employed in the eletrophilic cyclization from (Z)-thio- and (Z)-selenoenynes under ultrasound irradiation conditions to access 3-functionalized thiophenes and selenophenes, respectively. By using this strategy, the products (13 examples, 40% to 87% yield) were obtained by employing an alternative energy source, which characterizes this as a green and eco-friendly protocol. Similary, 3 functionalized tellurophenes were synthesized (5 examples, 28% to 65% yield) by using Oxone® as an oxidizing agent and glycerol as a solvent. During our investigations, we discovered the selective oxidative cleavage of tellurium tellurium bond by Oxone® following the cyclization reaction.