Hydrochloric Acid → 3-(5-acetyl-1H-indol-2-yl)-1H-thieno[3,2-c]pyrazole-5-carboxylic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

A solution of 3-(5-acetyl-1-tert-butoxycarbonyl-1H-indol-2-yl)-thieno[3,2-c]pyrazole-1,5-dicarboxylic acid 1-tert-butyl ester 5-methyl ester (115 mg, 0.213 mmol, Example 35) in tetrahydrofuran (5 mL) is treated with 2N hydrochloric acid (aqueous, 3 mL) and heated at 70° C. for 17 hours. The reaction is cooled to room temperature and neutralized with Na2CO3 (aqueous). The aqueous phase is extracted three times with ether (10 mL). Combined ether phases are washed with brine and dried over sodium sulfate. Purification by chromatography on 10 g silica gel cartridge (50-70% ethyl acetate gradient in heptane) afforded 3-(5-acetyl-1H-indol-2-yl)-1H-thieno[3,2-c]pyrazole-5-carboxylic acid methyl ester (15 mg, Example 36) as white solid; 1H NMR [(CD3)2SO)]: δ 13.82 (1H, s), 12.13 (1H, s), 8.34 (1H, s), 7.97 (1H, s), 7.78 (1H, d), 7.50 (1H, d), 6.90 (1H, s), 3.91 (3H, s), 2.61 (3H, s); LC/MS: 340 (M+H).

Provenance & Evidence