Pyridine → Benzhydryl 7-amino-3-cephem-4-carboxylate

Participants

Reaction Steps

To a suspension of the said starting material (3e) in dichloromethane (13 parts) under nitrogen are added at -5° to 0° C. pyridine (3 equivalents) and at -25° to -20° C. phosphorus pentachloride (2.7 equivalents). After stirring at -15° to -10° C. for 4 hours, the mixture is mixed with isobutanol (11 parts) cooled at -40° to -30° C., stirred at 0° to 5° C. for 2 hours, and kept at 0° to 5° C. overnight. The mixture is cooled to -25° to -20° C., mixed dropwise with triethylamine (14 equivalents), and kept at 0° to 5° C. overnight. The mixture is diluted with a mixture of ice-water and dichloromethane, and stirred for 20 minutes. The formed organic layer is taken, washed with hydrochloric acid, water, aqueous sodium hydrogen carbonate, and water, dried, and concentrated. The residue is crystallized from ethyl acetate to give 7beta-amino-3-cephem-4-carboxylic acid diphenylmethyl ester (5). Yield: 37.2%.

Provenance & Evidence