Dicyclohexylcarbodiimide → Tert.-butyl 7-[2-(2-tritylamino-4thiazolyl)-2-tetrahydropyranyloxyimino-acetamido]-3-acetoxymethyl-ceph-3-eme-4-carboxylate

Participants

Reaction Steps

A mixture of 0.362 g of the product of Step C, 0.244 g of tert.-butyl 7-amino-3-acetoxymethyl-ceph-3-eme-4-carboxylate, 0.280 g of dicyclohexylcarbodiimide and 4 ml of dry chloroform was stirred for 2 hours at room temperature and the mixture was vacuum filtered to remove dicyclohexylurea which was rinsed with chloroform. The filtrate was evaporated to dryness under reduced pressure and the residue was dissolved in 1 ml of ether. The solution was chromatographed over silica gel and was eluted with ether. The fractions with an Rf=0.38 were combined and evaporated to dryness under reduced pressure. The residue was taken up in isopropyl ether and effloresced. The mixture was vacuum filtered and the recovered product was rinsed with isopropyl ether to obtain 0.184 g of the syn isomer of tert.-butyl 7-[2-(2-tritylamino-4-thiazolyl)-2-tetrahydropyranyloxyimino-acetamido]-3-acetoxymethyl-ceph-3-eme-4-carboxylate.

Provenance & Evidence