General procedure for the synthesis of 7-methyl-1H-indazole from 2,6-dimethylaniline: tert-butyl nitrite (52 mL) was slowly added to a solution of chloroform (750 mL) of 2,6-dimethylaniline (25 g, 206 mmol) at room temperature and protected by nitrogen, stirred for 20 min, then potassium acetate (40 g, 412 mmol) and 18-crown-6 ( 5.4 g, 20.6 mmol). The reaction mixture was heated to reflux for 3 hours, followed by cooling to room temperature and continued stirring for 15 hours. Upon completion of the reaction, the solids in the mixture were removed by vacuum filtration and the solids were washed with chloroform (400 mL). The filtrates were combined, washed with water (2 x 250 mL), dried over anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. The residue was purified by fast column chromatography on silica gel, using hexane/ethyl acetate (9:1) as eluent to afford 7-methyl-1H-indazole as an orange solid (23 g, 85% yield). The structure of the product was confirmed by 1H NMR (CDCl3): δ 2.60 (s, 3H), 7.10 (m, 2H), 7.70 (d, 1H), 8.10 (s, 1H).
