Hydrochloric Acid → 1h-Indazole-3-carboxylic acid,4,5,6,7-tetrahydro-1-(phenylmethyl)-,ethyl ester

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Reaction Steps

To a stirring solution of 2.0 g (10.30 mmol) of 4,5,6,7-Tetrahydro-1H-indazole-3-carboxylic acid ethyl ester (Ainsworth, C. J. Am. Chem. Soc. 1957, 79, 5242) in 50 mL of DMF is added 1.85 g (13.838 mmol, 1.3 equiv) of K2CO3, followed by 1.35 mL (11.33 mmol, 1.1 equiv) of benzyl bromide. The reaction mixture is stirred 15 min at RT then heated at 60° C. for 16 h. The reaction is cooled to RT, poured into 100 mL 1N HCl, and extracted with Et2O (2×100 mL). The organic layers were washed with H2O (2×100 mL), dried (MgSO4), and the solvent removed in vacuo. Purification of the crude material by silica gel flash column chromatography using a gradient elution of hexane/EtOAc 6/1 to 3/1 afforded 1.05 g of 4,5,6,7-Tetrahydro-1-Benzyl-1H-indazole-3-carboxylic acid ethyl ester as a yellow oil which later solidified: 1H NMR (CDCl3, 300 MHz) δ7.37-7.23 (m, 3H), 7.13 (m, 2H), 5.31 (s, 2H), 4.39 (q, 2H, J=7.2), 2.74 (m, 2H), 2.40 (m, 2H), 1.72 (m, 4H), 1.39 (t, 3H, J=7.2).

Provenance & Evidence