SYNTHESIS AND REACTIVITY OF ZOL-2-YL)-1-BROMO-1,2-ETHANEDIONE-1-ARYLHYDRAZONES

The novel, highly versatile 2-(benzothiazol-2-yl)-1-bromo-1, 2-ethaned ione-1-arylhydrazones 3 were prepared and their behavior toward some n ucleophiles was investigated. Thus, reaction of 3 with the sodium salt of malononitrile afforded the aminopyrazolecar-bonitriles 5 that unde rgo cyclocondensation with hydrazine, formic acid, and formamide to gi ve the corresponding pyrazolo[3, 4-d]pyridazine 6, pyrazolo[3, 4-d]pyr imidinone 7, and pyrazolo[3, 4d]pyrimidine 8 derivatives, respectively . Similarly, reactions of 3 with each of acetylacetone, dibenzoylmetha ne, and benzoylacetonitrile afforded the corresponding pyrazole deriva tives 9, 10, and 11, respectively. The latter products undergo cycloco ndensation with hydrazine to afford the corresponding pyrazolo[3, 4-d] pyridazines 12, 13, and 14, respectively. (C) 1997 John Wiley & Sons, Inc.