p-Toluenesulfonic acid → methyl 3-iodo-1-(tetrahydro-2H-pyran-2-yl)-1H-indazole-5-carboxylate

Participants

Reaction Steps

In 50 mL R. B. flask, to a solution of 3-iodo-1H-indazole-5-carboxylic acid methyl ester (0.2 g, 0.66 mmol) in DCM (10 mL) was added 3,4-dihydropyran (0.117 g, 1.32 mmol) at 5° C. followed by the addition of PTSA (0.038 g, 0.264 mmol). The reaction was stirred for 2 h at RT, quenched with water (25 mL) and extracted with DCM (50 mL). The organic layer was separated and washed with water (2×25 mL) and dried over anhydrous Na2SO4, filtered and concentrated. The residue was triturated with n-pentane to give 3-iodo-1-(tetrahydro-pyran-2-yl)-1H-indazole-5-carboxylic acid methyl ester (0.15 g, 58%) as off white solid. MS (ESI, pos. ion) m/z: 302.7 (M-THP+1); 1H-NMR (300 MHz DMSO-d6): δ ppm 8.24 (t, 1 H, J=9 Hz), 8.13 (dd, 1 H, J=8.7, 1.5 Hz), 7.60 (d, 1 H, J=9 Hz), 5.73 (dd, 1 H, J=9.6, 2.7 Hz), 4.95 (m, 1H), 3.96-4.04 (m, 4H), 3.75-3.78 (m, 1H), 3.52-3.53 (m, 1H), 2.52-2.56 (m, 1H), 2.05-2.17 (m, 2H), 1.58-1.84 (m, 4H).

Provenance & Evidence