Water → 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-formyl-indole-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

To a solution of 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-hydroxymethyl-indole-1-carboxylic acid tert-butyl ester [373 mg, 0.794 mmol Intermediate (10)] in Dichloromethane (20 mL) is added Dess-Martin Periodinane (407 mg, 0.959 mmol). Stirred at room temperature for 30 minutes. Water (10 mL) is added and stirred for 30 minutes at room temperature. The reaction mixture is dissolved with ethyl acetate (30 mL) and washed twice with a mixture of 10% Na2S2O3/saturated NaHCO3 (4 ML) solution. The ethyl acetate phase is washed with water, NaHCO3, brine and dried over sodium sulfate. The residue is chromatographed on 10 g silica gel cartridge eluting with 30 to 40% ethyl acetate gradient in heptane to afford 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-formyl-indole-1-carboxylic acid tert-butyl ester [300 mg, 81%, Intermediate (11)] as a white solid; 1H NMR [(CD3)2SO)]: δ 10.079 (1H, s, CHO), 8.323 (1H, s), 8.318 (1H, d), 8.017 (1H, s), 7.978 (1H, d), 7.391 (1H, d), 7.345 (1H, s), 1.660 (9H, s), 1.341 (9H, s); TLC data Rƒ=0.37 (30% ethyl acetate in heptane). Step 2. To a solution of 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-formyl-indole-1-carboxylic acid tert-butyl ester [100 mg, 0.214 mmol, Intermediate (11)] in anhydrous tetrahydrofuran (5 mL) is added phenylmagnesium bromide (1M in tetrahydrofuran, 1 mL) at −78° C. The resulting reaction mixture is stirred at the same temperature for 1 h then quenched it by the addition of water at 0° C. (4 mL). The reaction mixture is extracted three times with ethyl acetate (30 mL). Combined ethyl acetate phases are washed with brine, dried over sodium sulfate and filtered. Evaporation of the solvent in vacuo yielded 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-(hydroxy-phenyl-methyl)-indole-1-carboxylic acid tert-butyl ester [99 mg, 85%, Intermediate (12)] as a white foam; LC/MS: (M+H, 546). Step 3. The mixture of 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-(hydroxy-phenyl-methyl)-indole-1-carboxylic acid tert-butyl ester [99 mg, 0.181 mmol, Intermediate (12)] in tetrahydrofuran (2 mL) and KOH (1M aqueous, 1 mL) is stirred at 60° C. under nitrogen for 22 hours. The solvent is removed in vacuo. To this slurry mixture is added water (2 mL) and brought pH to 6 by addition of 2N hydrochloric acid. The product is extracted three times with dichloromethane (20 mL) and the combined extracts are washed with brine then dried over sodium sulfate. The residue is chromatographed on 10 g silica gel cartridge, eluting with 50 to 100% ethyl acetate gradient in heptane to afford phenyl-[2-(1H-thieno[3,2-c]pyrazol-3-yl)-1H-indol-5-yl]-methanol [56 mg, 89%, Example 24] as a off-white solid; LC/MS: 346 (M+H), 328 [(M−18)+H]; TLC data: Rƒ=0.14 (50% ethyl acetate in heptane).

Provenance & Evidence