Phosphorus pentachloride → benzhydryl (6R)-8-oxo-3-[(Z)-prop-1-enyl]-7-[[(2Z)-2-[2-(tritylamino)-1,3-thiazol-4-yl]-2-trityloxyiminoacetyl]amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate

Participants

Reaction Steps

To a mixture of 2-(2-tritylaminothiazol-4-yl)-2-(Z)-trityloxyiminoacetic acid (III, R2a =Tr) (873 mg, 1.30 m moles) and dichloromethane (5 ml) was added phosphorus pentachloride (297 mg, 1.43 m moles) at -5° C. The mixture was allowed to stand for 20 min at the same temperature and added dropwise to a solution of diphenylmethyl 7-amino-3-(1-propenyl)-3-cephem-4-carboxylate hydrochloride (XIII, R3 =H: 443 mg, 1 m mole) and N,O-bis(trimethylsilyl)acetamide (0.74 ml, 4.4 m moles) in dichloromethane (5 ml) at -5° C. The reaction mixture was allowed to stand for 20 min. at the same temperature and poured into ice-water. Extraction of the mixture with ethyl acetate and evaporation of the extracts under reduced pressure gave the crude product as an oil, which was chromatographed on a column of silica gel (eluted with chloroform) to give the title compound as an amorphous powder. Yield 510 mg (48%).

Provenance & Evidence