Iodine → HCID 178497021, compound

Participants

Reaction Conditions

Reaction Steps

To a suspension of 1-acetyl-1H-thieno[3,2-c]pyrazole-5-carboxylic acid methyl ester [1.3 g, 5.79 mmol, Intermediate (25)] in methanol (30 mL) is added sodium methoxide (25 wt % in methanol). The resulting solution mixture is stirred at 60° C. oil bath for 20 minutes. The oil bath is removed and stirred for 5 minutes. To this is added a solution of iodine (1.76 g, 6.93 mmol) in dimethyl formamide (2 mL). The reaction mixture then heated to 60° C. for 1 hour. The solvent is removed in vacuo. The crude is partitioned between ethyl acetate (100 mL) and water (100 mL) and aqueous layer is further extracted with twice ethyl acetate (25 mL). The combined ethyl acetate phases are washed with brine, dried over sodium sulfate and filtered. The solvent is removed in vacuo to give 3-iodo-1H-thieno[3,2-c]pyrazole-5-carboxylic acid methyl ester [1.58 g, 89%, Intermediate (26)] as light yellow solid; 1H NMR [(CD3)2SO)]: δ 13.80 (1H, brs, NH), 7.947 (1H, s), 3.870 (3H, s).

Provenance & Evidence