Methanol → methyl 1H-indazole-3-carboxylate

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Reaction Steps

Concentrated H2SO4 (1 mL) was added to a solution of indazole-3-carboxylic acid (2.0 g, 12 mmol) in MeOH (40 mL). The reaction mixture was heated at reflux for 3 h, the MeOH was removed under reduced pressure and the residue was partitioned between diethyl ether (100 mL) and H2O (100 mL). Saturated sodium hydrogen carbonate solution was added (100 mL) and the diethyl ether layer was separated. The aqueous layer was further extracted with 2×200 mL of diethyl ether. The combined extracts were dried (MgSO4) and solvent removed under reduced pressure and the solid was recrystallised from cyclohexane/ethyl acetate to afford the title compound (1.29 g, 61%). Mp 158-159° C., lit 168-169° C. v.Auwers, Dereser Chem. Ber. 1919, 52, 1343. 1H-NMR (300 MHz, CDCl3) ppm 4.09 (s, 3H), 7.33-7.38 (m, 1H), 7.46-7.52 (m, 1H), 7.71-7.74 (m, 1H), 8.23-8.26 (m, 1H), 12.03 (s, 1H). MS(EI) m/z 176 [M+].

Provenance & Evidence