Novel reaction between 3,4,5,6-tetrachloro-1,2-benzoquinone and bis-azomethines

3,4,5,6-Tetrachloro-1,2-benzoquinone (o-CHL) reacted with N,N'-dicyclohexyl-1,2-ethanediimine 1a to give a transient condensation product, which underwent [4+2]cycloaddition reaction with another molecule of 1a. In a different manner, utilizing N,N'-diaryl-1,2-ethanediimines 1b,c as a dienophile led to an initial production of substituted o-CHL, followed by a [4+2]cycloaddition reaction with another molecule of 1b,c. A similar behavior was observed on the reaction of N,N'-di(alkyl/aryl)-p-xylenediimines 1a-f with the same acceptor.