Yield:351456-45-6 90%

Reaction Conditions:

with iodine;potassium hydroxide in N,N-dimethyl-formamide at 20; for 3 h;

Steps:

3-Iodo-1H-indazole (1a).

General procedure: 3-Iodoindazoles were obtained by direct iodination of commercial indazoles by the method previously described by Bocchi [28] with slight modifications. A solution of 1H-indazole (3 g, 25.4 mmol), iodine (12.7 g, 50.03 mmol) and potassium hydroxide (5.34 g, 95.25 mmol)in DMF (7 mL) was stirred for 3 h at room temperature. The reaction was quenched by dilution with saturated solution of sodium bisulfite (150 mL) and a precipitated was formed. The precipitated was filtered over vacuum and washed with water (3 × 30 mL). The solid was left to dry at 30 °C in a vacuum oven overnight obtaining 6.17 g of a pale yellow solid. Yield: 100%; m.p.: 136-138 °C (lit.:[36] 134-136 °C); IR (KBr) ν (cm-1): 3086 (NH); 424 (C-I). 1H-NMR δ (ppm): 13.50 (1H, s, H-1); 7.55(1H, d, J = 8.6 Hz, H-7); 7.45-7.40 (2H, m, H-6 and H-4); 7.19 (1H, dd, J = 7.5 Hz, H-5). 13C-NMR δ(ppm): 140.41; 127.22; 126.79; 121.23; 120.39; 110.51; 93.49; HRMS calculated for C7H5IN2: 243.9497,Found: 243.9499.3-Iodo-1H-indazole (1a). 3-Iodoindazoles were obtained by direct iodination of commercial indazoles by the method previously described by Bocchi [28] with slight modifications. A solution of 1H-indazole(3 g, 25.4 mmol), iodine (12.7 g, 50.03 mmol) and potassium hydroxide (5.34 g, 95.25 mmol) in DMF(7 mL) was stirred for 3 h at room temperature. The reaction was quenched by dilution with saturated solution of sodium bisulfite (150 mL) and a precipitated was formed. The precipitated was filtered over vacuum and washed with water (3 30 mL). The solid was left to dry at 30 °C in a vacuum oven overnight obtaining 6.17 g of a pale yellow solid. Yield: 100%; m.p.: 136-138 °C (lit.: [36] 134-136 °C)

References:

Vera, Gonzalo;Diethelm, Benjamín;Terraza, Claudio A.;Recabarren-Gajardo, Gonzalo [Molecules,2018,vol. 23,# 8,art. no. 2051]