Síntese de 2-aril-3-(organosselanil)tieno[2,3-b]piridinas promovida por luz visível

Abstract

In the present work, an alternative and mild method for the synthesis of 2-aryl-3-(organoselanyl)thieno[2,3-b]pyridines promoted by visible light was developed. The synthetic strategy developed to obtain these compounds involves the homolytic cleavage of the Se-Se bond of diorganoyl diselenides in the presence of visible light. Thus, the reaction consists of the intramolecular cyclization of different 3-(arylethynyl)-2-(alkylthio)pyridines promoted by diorganoyl diselenides, irradiation of blue LEDs (50 W) and hexane as solvent, in the absence of external photocatalysts under mild conditions of reaction. Twenty-two compounds were obtained with yields ranging from moderate to excellent (57-99%) in reaction times from 0.5 h to 72.0 h. In addition, the method developed was efficient in terms of scale-up (3 mmol), which provided the desired product in a yield of 99% (1.09 g) after 1 h of reaction, demonstrating the applicability of this reaction in a possible industrial scale.