反应详情

To a solution of 3-(2,5-dimethyl-phenyl)-4-hydroxy-8-methoxy-1-oxa-8-aza-spiro[4.5]dec-3-en-2-one (120 mg, 0.40 mmol), triethylamine (0.08 ml, 60 mg, 0.60 mmol) and 4-dimethylaminopyridine DMAP (2 mg, 0.02 mmol) in 4 ml THF at 0° C. was added a solution of ethyl chloroformate (0.05 ml, 52 mg, 0.50 mmol) dissolved in 1 ml THF dropwise. The suspension was kept at 0° C. for 30 minutes under argon and left stirring at room temperature overnight. Then the solvent was removed under vacuum. Ethyl acetate was added to the residue and the precipitation was filtered off. The filtrate was concentrated under vacuum to give the crude product, which was purified by column chromatography on silica gel (ethyl acetate/cyclohexane 1:9). Yield: 111 mg of carbonic acid 3-(2,5-dimethylphenyl)-8-methoxy-2-oxo-1-oxa-8-aza-spiro[4.5]dec-3-en-4-yl ester ethyl ester (title compound P1.1) as a light yellow gum.

1. waitleft
2. customThen the solvent was removed under vacuum
3. additionEthyl acetate was added to the residue
4. customthe precipitation
5. filtrationwas filtered off
6. concentrationThe filtrate was concentrated under vacuum