Cephalothin → HCID 70636083, compound

Participants

Reaction Steps

To a cooled (0°), stirred solution of 7.75 g. of 7-(2-thienylacetamido)-7-methoxy-3-acetoxymethyl-3-cephem-4-carboxylic acid [prepared from cephalothin in accordance with procedures described by G. A. Koppel and R. E. Koehler, J. Amer. Chem. Soc., 95, 2403 (1973)] in 46 ml. of dry pyridine was added 5.02 ml. of acetic anhydride. The reaction mixture was allowed to stir with cooling for 2 hours, after which time the mixture was evaporated in vacuo to near dryness. The residue was dissolved in ethyl acetate, and the resulting solution was extracted 3 times with aqueous sodium bicarbonate. The aqueous extracts were combined, layered with ethyl acetate, and acidified with cold 1N.HCl. The organic layer was separated, washed with brine and dried over anhydrous sodium sulfate. Evaporation in vacuo to dryness provided 5.29 g. (68.2 percent) of the title product as a brown froth. Thin layer chromatography of the methyl ester derived from diazomethane exhibited a single spot. For identification purposes a small portion of the product acid was also converted to the corresponding benzhydryl ester using diphenyldiazomethane. Chromatography on a small silica gel column provided pure benzhydryl 7-(2-thienylacetamido)-7-methoxy-3-acetoxymethyl-2-cephem-4-carboxylate: ir (CHCl3) 1780 cm-1 (β-lactam); nmr (CDCl3) δ1.92 (s, 3, OAc), 3.42 (s, 3, OCH3), 3.85 (s, 2, side chain CH2), 4.55 (s, 2, --CH2OAc), 5.01 (m, 1, C4 --H), 5.35 (s, 1, C6 --H) and 6.35 (m, 6, CH2).

Provenance & Evidence