Nucleophilic cyclization of 3-alkynylquinoxaline-2-carbonitriles into pyrido[3,4-b]quinoxalines
作者:Alexander S. Tyaglivy、Anna V. Gulevskaya、Alexander F. Pozharskii、Olga I. Askalepova
DOI:10.1016/j.tet.2013.09.005
日期:2013.11
3-Alkynylquinoxaline-2-carbonitriles have been synthesized from 3-chloroquinoxaline-2-carbonitrile via the Sonogashira reaction. Treatment of 3-alkynylquinoxaline-2-carbonitriles with an alkylamine or ammonia has been shown to produce stable enamines, e.g., (Z)-3-(2-aryl-2-aminovinyl)quinoxaline-2-carbonitriles. Their base-induced cyclization gave the previously unknown pyrido[3,4-b]quinoxalin-1(2H)-imines or pyrido[3,4-b]quinoxalin-1-amines. 3-Alkynylquinoxaline-2-carbonitriles were directly transformed into pyrido[3,4-b]quinoxalin-1(2H)-imines by heating with an alkylamine and K2CO3 in DMF. The ionization constants, and absorption and fluorescent properties of the resulted pyrido[3,4-b] quinoxalin-1(2H)-imines were measured. (C) 2013 Elsevier Ltd. All rights reserved.