Unexpected reaction of 2-hydrazinoperimidine with maleic anhydride: Syntheses of (8-amino-9-oxo-9,10-dihydro-8H-imidazo[1,2-a]perimidin-10-yl)acetic acid and its azomethine derivatives

The reaction of 2-hydrazinoperimidine (3) and maleic anhydride in mild conditions afforded the formation of an unexpected product, namely (8-amino-9-oxo-9,10-dihydro-8H-imidazo[1,2-a]perimidin-10-yl)acetic acid (5). The possible mechanism of this reaction is discussed. Schiff bases (9a-f) were prepared from 5 using corresponding aldehydes. The structures of the prepared compounds were established with spectral analysis including NOESY 2D experiments.{A figure is presented}.