N-(Thieno[2,3-b]pyridin-3-yl)cyanoacetamides: synthesis and cyclizations

¹ Kuban State University
² The Federal State Unitary Enterprise “Institute of Chemical Reagents and High Purity Chemical Substances” of National Research Centre “Kurchatov Institute”, 3 Bogorodsky Val, Moscow, 107076, Russia
³ ChemEx Lab, Vladimir Dal’ Lugansk National University
⁴ North Caucasus Federal University

Published: 14 November 2020 by MDPI in The 24th International Electronic Conference on Synthetic Organic Chemistry session General Organic Synthesis

https://doi.org/10.3390/ecsoc-24-08400

Abstract:

A series of N-(thieno[2,3-b]pyridin-3-yl)cyanoacetamides were prepared by reaction of 3-aminothieno[2,3-b]pyridines with 1-cyanoacetyl-3,5-dimethytlpyrazole. Upon treatment with alkali, N-(2-alkoxycarbonylthieno[2,3-b]pyridin-3-yl)cyanoacetamides undergo Camps-type cyclization to give dipyridothiophenes. The relative stability of their tautomers was estimated by quantum chemical calculations. In contrast, cyclization of 3-(2-cyanoacetamido)thieno[2,3-b]pyridine-2-carboxamides lead to the formation of pyrido[3’,2’:4,5]thieno[3,2-d]pyrimidines.

Keywords: heterocyclization, Camps reaction, thienopyridines, cyanoacetylation

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