On the one pot syntheses of chromeno[4,3-b]pyridine-3-carboxylate and chromeno[3,4-c]pyridine-3-carboxylate and dihydropyridines

Abstract

Substituted chromenos, dihydropyridines and pyridines have been important in the syntheses of compounds having interesting pharmacological properties. Therefore, we found of interest to synthesize chromenopyridines and chromenodihydropyridines (i.e., fused chromeno and dihydropyridine or pyridine rings) to further study their biological activity. Here, we propose one-pot syntheses for substituted ethyl-2,4-dimethyl-5-oxo-5H-chromeno[4,3-b]pyridine-3- carboxylates, ethyl-2,4-dimethyl-5-oxo-5H-chromeno[3,4-c]pyridine-3-carboxylates and their respective 1,4-dihydropyridines based on a modified Hantzsch pyridine synthesis using 2-hydroxyaryl aldehydes, with electron withdrawing and electron donating groups on the phenyl ring, as starting reactants. Sixteen compounds were synthesized by the described method and fully characterized. An average yield of 37% was obtained for the different derivatives. © 2010 Sociedade Brasileira de Química.

Os cromenos, dihidropiridinas e piridinas substituídos têm-se revelado importantes na síntese de compostos com propriedades farmacológicas interessantes. Consequentemente, achamos importante a síntese de cromenopiridinas e cromenodihidropiridinas (ou seja, anéis fundidos do cromeno e da dihidropiridina ou da piridina) de forma a pesquisar a sua atividade biológica. Neste estudo, propomos a síntese “one-pot” para 2,4-dimetil-5-oxo-5H-cromeno[4,3-b]piridina-3-carboxilatos de etilo, 2,4-dimetil-5-oxo-5H-cromeno[3,4-c]piridina-3-carboxilatos de etilo substituídos e as suas respectivas 1,4 dihidropiridinas, baseada numa síntese modificada da piridina de Hantzsch usando 2-hidroxiaril aldeído, com os grupos que retiram e doam elétrons no anel fenil, como reagentes iniciais. Dezesseis compostos foram sintetizados pelo método descrito e completamente caracterizados. Um rendimento médio de 37% foi obtido para os diferentes derivados.