ChemInform Abstract: Synthesis and Reactions of 3-Carboxytropolone. Conversion to Heterocycle-Fused Troponoid Compounds

The haloform reaction of 3-acetyltropolone (1) afforded 3-carboxytropolone (2) which was treated with diazomethane to give 2-methoxy-3-methoxycarbonyltropone (3a) and 2-methoxy-7-methoxycarbonyltropone (3b). The tropolone 2 reacted with hydrazine to afford 2-hydrazino-3-hydrazinocarbonyltropone (10) or 2-hydrazinotropone (11), depending on the reaction time. The reaction of 2 with phenylhydrazine produced 3-hydroxy-1-phenyl-1,8-dihydrocycloheptapyrazol-8-one (14). The treatment of 2-methoxy-3-methoxycarbonyltropone (3a) with hydrazine or phenylhydrazine gave cyclization products 12 and 15, respectively. The reaction of 2-methoxy-7-methoxycarbonyltropone (3b) with hydrazine, phenylhydrazine, or methylhydrazine gave 2-hydrazino- (13), 2-(2-phenylhydrazino)- (16), and 2-(2-methylhydrazino)-7-methoxycarbonyltropone (17), respectively.