Isopropyl chloroformate → 4-[4-(6-Cyano-2,3-difluoro-phenoxy)-pyrazolo-[3,4-d]pyrimidin-1-yl]-piperidine-1-carboxylic acid isopropyl ester

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Reaction Steps

Isopropyl chloroformate (Aldrich Chemical Company, Inc., Milwaukee, Wis., USA 1M in toluene; 0.35 mL, 0.35 mmol) was added to a mixture of 3,4-difluoro-2-(1-piperidin-4-yl-1H-pyrazolo[3,4-d]pyrimidine-4-yloxy)-benzonitrile trifluoroacetate salt (which was prepared from 4-[4-(6-cyano-2,3-difluoro-phenoxy)-pyrazolo[3,4-d]pyrimidin-1-yl]-piperidine-1-carboxylic acid tert-butyl ester [Example 49] following the procedure described for the preparation of Intermediate 29; 180 mg, 0.35 mmol), diisopropylethylamine (136 mg, 1.06 mmol) in dichloromethane (6 mL). The reaction was stirred at room temperature overnight. Water was added to quench the reaction and the aqueous layer was extracted three times with dichloromethane. The combined organic layers were dried (sodium sulfate), filtered, evaporated and purified by flash chromatography on silica gel, eluting with 4% methanol/dichloromethane to give 4-[4-(6-cyano-2,3-difluoro-phenoxy)-pyrazolo-[3,4-d]pyrimidin-1-yl]-piperidine-1-carboxylic acid isopropyl ester (147 mg, 85%) as a white solid. Mass spectrum MH+=443.

Provenance & Evidence