Ethyl chloroformate → 7H-Pyrrolo(2,3-d)pyrimidine-5-carboxylic acid, 4-chloro-, ethyl ester

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Reaction Conditions

Reaction Steps

A solution of 5-bromo-4-chloropyrrolo[2,3-d]pyrimidine (Example 35) (232 mg; 1 mmol) in anhydrous THF (5 mL) was cooled to -78° C. under argon and a solution of n-butyl lithium (1.3 mL of 2.31M) was added at such a rate that the temperature of the reaction mixture remained below -72° C. After stirring the reaction mixture at -78° C. for 45 minutes, a solution of ethyl chloroformate (0.15 mL) in THF (2 ml) was added slowly, maintaining the reaction temperature below -72° C. The reaction mixture was stirred at -78° C. for 2 hours then allowed to warn to room temperature. A saturated solution of NH4Cl (20 mL) was added to the reaction mixture. The organic layer was separated and the aqueous layer was extracted with ethyl acetate (2×25 mL). The combined organic extracts were dried and evaporated to a white solid, yield 210 mg (92%): m.p. 140°-141° C.

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