[NH:1]1[C:5]2[CH:6]=[CH:7][S:8][C:4]=2[CH:3]=[N:2]1.[OH-].[K+].[I:11]I>CN(C=O)C>[I:11][C:3]1[C:4]2[S:8][CH:7]=[CH:6][C:5]=2[NH:1][N:2]=1To a solution of 1H-thieno[3,2-c]pyrazole (1.0 g, 8.05 mmol) in DMF (65 ml) at room temperature was added potassium hydroxide (1.36 g, 24.2 mmol) and iodine (3.07 g, 12.1 mmol). The maroon reaction mixture was stirred at room temperature for 3 h then quenched with 10% aqueous Na2S2O3 and diluted with water. The mixture was extracted with EtOAc (2×). The combined organics were washed with water, sat LiCl, and sat NaCl, then dried over MgSO4 and concentrated to afford 2.0 g (99%) of 3-iodo-1H-thieno[3,2-c]pyrazole as a light brown solid. 1H NMR (DMSO-d6, 300 MHz): δ (ppm) 13.38 (br. s., 1H), 7.68 (d, J=5.3 Hz, 1H), 7.21 (d, J=5.3 Hz, 1H).
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