p-Toluenesulfonic acid → p-Nitrobenzyl 7-amino-3-methylenecepham-4-carboxylate p-toluenesulfonate

Participants

Reaction Conditions

Reaction Steps

To a solution of 965 mg. of p-nitrobenzyl 7-phenoxyacetamido-3-methylenecepham-4-carboxylate in 10 ml. of methylene chloride were added 175 mg. of dry pyridine and 460 mg. of phosphorus pentachloride and the mixture was stirred for five hours at room temperature. Thereafter the reaction mixture was cooled to 0° C. and 50 ml. of cold methanol were added. Following a stirring period of one-hour at room temperature the reaction mixture was evaporated in vacuo to remove the solvents and the residual reaction product mixture was dissolved in a mixture of ethyl acetate and water. The pH was adjusted to pH 7 and the ethyl acetate layer was separated and was washed with water and dried. One equivalent of p-toluene sulfonic acid was added to the dried solution and on cooling 600 mg. of p-nitrobenzyl 7-amino-3-methylene-cepham-4-carboxylate p-toluenesulfonate formed as a crystalline precipitate. The product was purified by recrystallization from a mixture of 12 ml. of methanol 24 ml. of ether and 15 ml. of petroleum ether.

Provenance & Evidence