Indazole is well known as an aza analogue of indole, and a number of indazole derivatives have powerful pharmacological activities, for example, anti-inflammatory, anti-tumor, anti-HIV, anti-depressant, and contraceptive activities, etc. 1 Various methods for the preparation of indazoles have been reported. The cyclization of o-methylbenzenediazonium salts, 2 N-(2-nitrobenzylideneamines), 3 o-methyl-N-nitrosoanilines, 4 and o-acylarylhydrazines ...