Acetamide, 2-(trimethylsilyl)- → 4-Nitrobenzyl 7-[2-(2-formamidothiazol-4-yl)-2-ethoxyiminoacetamido]-3-hydroxy-3-cephem-4-carboxylate

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Reaction Steps

N,N-Dimethylformamide (0.114 g.), phosphoryl chloride (0.240 g.) and ethyl acetate (0.5 ml.) were reacted in a conventional manner to give a Vilsmeier reagent. Ethyl acetate (5 ml.) and 2-(2-formamidothiazol-4-yl)-2-ethoxyiminoacetic acid (syn isomer, 0.35 g.) were added at the same temperature for 30 minutes to give the activated acid solution. On the other hand, trimethylsilylacetamide (1.31 g.) and bis(trimethylsilyl)acetamide (1.14 g.) were added to a suspension of 4-nitrobenzyl 7-amino-3-hydroxy-3-cephem-4-carboxylate (0.50 g.) in ethyl acetate (7.5 ml.) and stirred at room temperature for an hour. To the solution was added the activated acid solution obtained above all at once at -10° C., and stirred at the same temperature for 30 minutes. Water (15 ml.) and ethyl acetate (15 ml.) were added to the resultant solution. The organic layer was separatwashed with a saturated aqueous solution of sodium bicarbonate (15 ml.) and water (10 ml.), dried over magnesium sulfate and concentrated in vacuo. The residue was pulverized with diethyl ether and the precipitates were collected by filtration to give 4-nitrobenzyl 7-[2-(2-formamidothiazol-4-yl)-2-ethoxyiminoacetamido]-3-hydroxy-3-cephem-4-carboxylate (syn isomer, 0.634 g.).

Provenance & Evidence