The behaviour of [1]benzopyrano[4,3-c][1,5]benzodiazepin-7(8H)-ones 1a–c towards some N-binucleophiles have been studied. With non-aromatic hydrazines the reaction carried out in acidic medium led exclusively to the unexpected [1]benzopyrano[4,3-c]pyrazol-4-ones 4 and 5. Compounds 1 reacted under less drastic conditions with variously substituted amidines and guanidines to give 5H-[1]benzopyrano[4,3-d]pyrimidin-5-ones (10a–d). A general mechanism is proposed to explain the formation of the obtained heterocycles.
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