Novel heterocyclization of hydrazinopyridazinones with dimethyl acetylenedicarboxylate with dehydrogenation and rearrangement
Abstract
5-Hydrazinopyridazin-3(2H)-ones 1 reacted with dimethyl acetylenedicarboxylate 2 to give 4,6-dihydropyridazino[4,5-c] pyridazin-5-(1H)-ones 3 by cyclization with dehydrogenation. On the other hand, the reaction of 4-bromo-5-hydrazino- and 5-bromo-4-hydrazinopyridazin-3(2H)-ones 8 and 10 with diester 2 resulted in the novel cyclization with rearrangement to give compounds 3 and 9 together with the expected cyclization products.