反应详情

(3S-trans)-[[3-[(t-Butyloxycarbonyl)amino]-4-methyl-2-oxo-1-azetidinyl]oxy]acetic acid. diphenylmethyl ester (4.4 g1 10.0 mmol) was dissolved in a solution of 33 ml of trifluoroacetic acid and anisole (3.3 ml; 30.0 mmol) at -10° C. The mixture was evaporated in vacuo 10 minutes later and the residue was stirred with ether, filtered off and dried over P2O5 to give colorless crystals of (3S)-[[3-amino-4-methyl-2-oxo-1-azetidinyl]oxy]acetic acid, trifluoroacetate salt (yield 2.87 g). The salt (2.87 g; 10.0 mmol) was suspended in dry acetonitrile. MSTFA (5.57 ml; 30.0 mmol) was added and stirring was continued for 30 minutes. After evaporating in vacuo the residue was dissolved in dry tetrahydrofuran and then added to a mixture of the [[[(4-methoxyphenyl)methoxy]-carbonyl]amino]benzeneacetic acid 1-hydroxybenzotriazole ester (4. g, 10.0 mmol) in 25 ml of dry tetrahydrofuran at 0° C., stirred overnight at room temperature and evaporated in vacuo. After adding ether the crude silylated product was decomposed with 1 ml methanol. After removing the solvents in vacuo the residue was stirred with ether/petroleum ether to give colorless crystals of the title compound.

1. customThe mixture was evaporated in vacuo 10 minutes later
2. filtrationfiltered off
3. dry with materialdried over P2O5