Phosphorus pentachloride → benzhydryl (6R)-3-(chloromethyl)-7-[[(2Z)-2-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethoxy]imino-2-[2-(tritylamino)-1,3-thiazol-4-yl]acetyl]amino]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate

Participants

Reaction Steps

To an ice-cooled solution of (Z)-2-t-butoxycarbonylmethoxyimino-2-(tritylaminothiazol-4-yl)acetic acid (IVg') (2.71 g, 5 mmoles) in CH2Cl2 (20 ml) was added PCl5 (1.24 g, 6 mmoles), and the solution was stirred for 20 minutes at room temperature. The acid chloride solution was added under ice-cooling to a solution of the silylated 7-ACA ester, which was prepared by adding bis(trimethylsilyl)acetamide (BSA, 3.7 ml, 15 mmoles) to a stirred suspension of benzhydryl 7-amino-3-chloromethyl-3-cephem-4-carboxylate hydrochloride (V) (2.25 g, 5 mmoles) in CH2Cl2 (20 ml). The reaction mixture was stirred at room temperature for 30 minutes, diluted with ethyl acetate (200 ml) and washed with an aqueous NaHCO3 solution and water. After drying over Na2SO4, the solution was evaporated and the residue was purified by silica gel chromatography (Wako gel C-200, 60 g). The desired fractions, eluted by CHCl3, were combined and concentrated to give 3.16 g (67%) of the title compound VIg'.

Provenance & Evidence