Triethylamine → 2-Cyclopropyl-7-[(3S)-3-(dimethylamino)pyrrolidin-1-yl]-5-methyl-6-vinyl-1,3-benzoxazole-4-carbonitrile

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Reaction Conditions

Reaction Steps

2-Cyclopropyl-7-fluoro-5-methyl-6-vinyl-1,3-benzoxazole-4-carbonitrile (I-180) (100 mg, 0.41 mmol) was dissolved in dimethyl sulfoxide (2 ml), then at room temperature, triethylamine (86 μl, 0.62 mmol) and (3S)-3-(dimethylamino)pyrrolidine (68 μl, 0.54 mmol) were added. The solution was stirred under nitrogen atmosphere at 90° C. for 4.5 hours. After cooling to room temperature, the reaction liquid was fractionated with ethyl acetate and an aqueous saturated sodium hydrogencarbonate solution. The aqueous layer was further extracted twice with ethyl acetate. The organic layers were combined, washed with saturated brine, and dried over anhydrous sodium sulfate. The insoluble matter was separated by filtration, then the solvent was evaporated away, and the resulting residue was purified by preparative TLC (eluent, chloroform:methanol=9:1) to obtain a roughly-purified product (123 mg, 89%) as a pale brown solid. This was recrystallized from diisopropyl ether and hexane to obtain the entitled compound (79 mg) as a white solid.

Provenance & Evidence