Studies on the reactions of cyclic oxalyl compounds with hydrazines or hydrazones : Synthesis and reactions of 4‐benzoyl‐1‐(3‐nitrophenyl)‐5‐phenyl‐1 H ‐pyrazole‐3‐carboxylic acid

The 1 H ‐pyrazole‐3‐carboxylic acid 2 , obtained from the furan‐2,3‐dione 1 and N ‐Benzylidene‐ N '‐(3‐nitrophenyl) hydrazine, was converted via reactions of its acid chloride 3 with various alcohols or N‐nucleo‐philes into the corresponding ester or amide derivatives 4 or 5 , respectively. Nitrile 6 and anilino‐pyrazole acid 7 derivatives of 2 were also obtained by dehydration of 5a in a mixture of SOCl 2 with DMF and reduction of 2 with sodium polysulphide, respectively. While cyclocondensation reactions of 2 or 7 with phenyl hydrazine or hydrazine hydrate and 6 with only anhydrous hydrazine lead to derivatives of pyrazolo[3,4‐ d ]‐pyridazinone 8 and pyrazolo[3,4‐ d ]pyridazine amine 9 , respectivel. The reaction of 2 with 2‐hydrazinopyri‐dine provided hydrazono‐pyrazole acid derivative 10 , which was decarboxylated to give hydrazono‐pyra‐zole derivative 11 . Pyrazolo[4,3‐ d ]oxazinone 12 and 2‐quinolyl pyrazolo[3,4‐ d ]pyridazine 13 derivatives were also prepared by cyclocondensation reactions of 2 with hydroxylamine hydrochloride and 7 with acetaldehyde, respectively.