Cesium carbonate → 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-(tert-butyl-dimethyl-silanoxy)-indole-1-carboxylic acid tert-butyl ester

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Reaction Steps

To a solution of 3-iodo-thieno[3,2-c]pyrazole-1-carboxylic acid tert-butyl ester (200 mg, 0.57 mmol, Example 5B) and bis-(diphenylphosphinoferrocene)-dichloro palladium (complex with dichloromethane 1:1, 21 mg, 0.03 mmol) in 1,4-dioxane (5 mL) is added 5-(tert-butyl-dimethyl-silanoxy)-1-(tert-butoxycarbonyl)-1H-indole-2-boronic acid (335 mg, 0.86 mmol, prepared as described in Example 4-6 of International Patent Application Publication No. WO 02/32861) followed by a solution of cesium carbonate (741 mg, 2.28 mmol) in water (2 mL). The mixture is stirred at reflux for 15 minutes. Then it is diluted with ethyl acetate and washed with water and brine. The organic layer is dried over magnesium sulfate and concentrated. The residue is chromatographed through silica gel (n-heptane-ethyl acetate, 95:05 as eluant) to afford 200 mg (61%) of 2-(1-tert-butoxycarbonyl-1H-thieno[3,2-c]pyrazol-3-yl)-5-(tert-butyl-dimethyl-silanoxy)-indole-1-carboxylic acid tert-butyl ester as a white foam. LC/MS: RT=4.29 minutes, 570.1 m/e.

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