Benzyl chloroformate → 5,6-Dichloro-2-(4-methoxy-3-nitro-phenyl)-benzoimidazole-1-carboxylic acid benzyl ester

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Reaction Steps

Dimethylformamide (25 mL) was added to 5,6-dichloro-2-(4-methoxy-3-nitro-phenyl)-1H-benzoimidazole (1.01 g, 3 mmol) from Step A. As the mixture stirred, sodium hydride (0.168 g, 4.2 mmol) was gradually added. After 3 hours, benzyl chloroformate (0.857 mL, 6 mmol) was added dropwise to the mixture. The reaction mixture was stirred overnight and then was partitioned between water (1,000 mL) and ethyl acetate (500 mL). The solvent was removed on the rotary evaporator and the residue triturated with 4:1 hexane:ethyl acetate to give the product (0.62 g), mp 212-214° C.

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