Phosphorus oxychloride → Benzhydryl 7-(2-benzyloxycarbonylmethoxyimino-4-bromo-3-oxobutyramido)-3-vinyl-3-cephem-4-carboxylate

Beteiligte Stoffe

Reaktionsschritte

Vilsmeier reagent prepared from N,N-dimethylformamide (0.67 ml) and phosphorus oxychloride (0.79 ml) was suspended in dry tetrahydrofuran (25 ml). Thereto was added 2-benzyloxycarbonylmethoxyimino-4-bromo-3-oxobutyric acid (2.8 g) at 0° C. with stirring, and the stirring was continued at 0° to 5° C. for an hour to prepare the activated acid solution. This activated acid solution was added at a time to a solution of benzhydryl 7-amino-3-vinyl-3-cephem-4-carboxylate hydrochloride (2.2 g) and trimethylsilylacetamide (7.0 g) in methylene chloride (30 ml) at -35° C., and the mixture was stirred at -10° to -5° C. for 30 minutes. The reaction mixture was poured into ethyl acetate (200 ml), and the separated organic solution was washed with a saturated aqueous sodium bicarbonate and a saturated aqueous sodium chloride, followed by drying over magnesium sulfate. Removal of the solvent gave benzhydryl 7-(2-benzyloxycarbonylmethoxyimino-4-bromo-3-oxobutyramido)-3-vinyl-3-cephem-4-carboxylate (2.8 g).

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