Phosphorus pentachloride → p-Nitrobenzyl 7-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2-ethoxyiminoacetamido]-3-mesyloxy-3-cephem-4-carboxylate

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Reaction Steps

To a solution of phosphorus pentachloride (57 g) in methylene chloride (1 () was added pyridine (22 ml) at -20° C. and the mixture was stirred for 30 minutes at -20° C. p-Nitrobenzyl 7-(2-phenylacetamido)-3-mesyloxy-3-cephem-4-carboxylate (50 g) was added to the solution at 5° C. and stirred at the same temperature for 1 hour. Methanol (56 ml) was added to the solution at -30° C. and stirred at -15° C. for 30 minutes. To the solution were added pyridine (80 ml) and diisopropylethylamine (31.4 ml) at -30° C. 2-(5-Amino-1,2,4-thiadiazol-3-yl)-2-ethoxyiminoacetyl chloride hydrochloride (syn isomer) (26.7 g) was added to the solution at -30° C. by portions and stirred at -15° C. for 1 hour Water (1 l) was added to the solution and stirred for 30 minutes. A resultant precipitate was collected by filtration and washed with diisopropyl ether and air-dried to give p-nitrobenzyl 7-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2-ethoxyiminoacetamido]-3-mesyloxy-3-cephem-4-carboxylate (syn isomer) (40 g).

Provenance & Evidence