Recyclization of 2-Iminochromenes via Ketene Aminal Intermediates: One-Pot, Three-Component Reaction for Synthesis of 1,4-Dihydropyridines-fused-1,3-diazaheterocycles

Abstract

An efficient, one-pot synthesis of 4-aryl-1,4-dihyropyrido[1,2-a]-fused-1,3-diazaheterocycles by three-component reaction of 1,n-diamine, nitroketene dithioacetal (1,1-di(methylthio)-2-nitroethene), and 2-iminochromenes in EtOH is reported. This new protocol has the advantages of good yields, short reaction times, and convenient operation. The structures were corroborated spectroscopically (infrared, ¹H and ¹³C NMR, and electron impact–mass spectrometry) and by elemental analyses. A plausible mechanism for this type of recyclization is proposed.

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GRAPHICAL ABSTRACT

Keywords:

• 1,4-Dihydropyridines
• 2-iminochromene
• ketene aminal
• three-component reaction