1-Bromopropane → 6-bromo-2-propyl-2H-indazole-4-carboxylic acid methyl ester

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Reaction Conditions

Reaction Steps

The title compounds were prepared in the same manner as described for example 42 (step a) from 6-bromo-1H-indazole-4-carboxylic acid methyl ester (3.0 g, 11.66 mmol) and 1-propyl bromide (1.59 g, 12.94 mmol) wherein the contents were heated at 40° C. for 30 min. The obtained crude products were purified by silica gel chromatography (eluent: 10% ethyl acetate in petroleum ether) to afford the title compounds 6-bromo-1-propyl-1H-indazole-4-carboxylic acid methyl ester (700 mg, 20%) and undesired isomer 6-bromo-2-propyl-2H-indazole-4-carboxylic acid methyl ester (700 mg, 20%) as white solids. 1H NMR (400 MHz, DMSO-d6): (N1-propyl isomer): δ 0.83-0.80 δ (t, J=7.6, 3H), 1.84-1.81 (t, J=14.4 Hz, 2H), 3.95-3.94 (d, J=5.2 Hz 3H), 4.45-4.43 (t, 2H), 7.84 (d, J=1.2 Hz, 1H), 8.43 (d, J=14 Hz, 2H). LCMS (ES+): m/z=297.06.

Provenance & Evidence