Triethylamine → Carbonic acid ethyl ester 3-methoxy-9-oxo-8-(2,4,6-trimethyl-phenyl)-2,3,4,5-tetrahydro-1H,9H-pyrazolo[1,2-a][1,2,5]triazepin-7-yl ester

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Reaction Conditions

Reaction Steps

To a solution of 3-methoxy-8-(2,4,6-trimethyl-phenyl)-tetrahydro-pyrazolo[1,2-a][1,2,5]triazepine-7,9-dione (106 mg, 0.33 mmol), triethylamine (0.070 ml, 51 mg, 0.50 mmol) and a catalytic amount of 4-dimethylaminopyridine in tetrahydrofuran (2 ml) at 0° C. was added ethyl chloroformate (0.035 ml, 40 mg, 0.37 mmol) dropwise. The suspension was stirred at 0° C. for 20 minutes, treated with more triethylamine (0.070 ml, 51 mg, 0.50 mmol) and ethyl chloroformate (0.035 ml, 40 mg, 0.37 mmol) dropwise, and further stirred at 0° C. for 10 minutes. The solvent was evaporated, the residue diluted with ethyl acetate, the organic phase washed with water and brine, dried over sodium sulfate and concentrated. The gummy residue was triturated in cyclohexane and diethyl ether, stirred at room temperature, filtered and dried. Yield: 100 mg of carbonic acid ethyl ester 3-methoxy-9-oxo-8-(2,4,6-trimethyl-phenyl)-2,3,4,5-tetrahydro-1H,9H-pyrazolo[1,2-a][1,2,5]triazepin-7-yl ester (title compound P1.2) as a pale yellow solid.

Provenance & Evidence