Methyl 3-amino-4-methylbenzoate → methyl 1H-indazole-6-carboxylate

Participants

Reaction Steps

To a stirred solution of methyl 3-amino-4-methylbenzoate (4.98 g, 30 mmol) in acetic acid (50 mL) was added sodium nitrite (2.29 g, 33.0 mmol) in water (5 mL) dropwise at 0° C. After 5 min a solid precipitated. The cooling bath was removed and the reaction mixture was brought to room temperature. More acetic acid (50 mL) was added to dissolve the precipitate; this was stirred for 2 h, and a clear dark solution appeared. After 4 h, acetic acid was evaporated and the residue was added to a saturated aqueous sodium bicarbonate solution; this was extracted with ethyl acetate (3×60 mL). The combined extracts were washed with brine (10 mL), dried (MgSO4) and evaporated. The residue solidified upon standing at room temperature to give an amorphous solid (3.9 g, 73%): MS (ES) m/z 177 (M+); 1H NMR (CDCl3): 10.05 (1H, br s), 8.29 (1H, s), 8.16 (1H, s), 7.86 (1H, d, J=8.0 Hz), 7.81 (1H, d, J=8.0 Hz), 3.97 (3H, s).

Provenance & Evidence