Phosphorus oxychloride → benzhydryl (6R,7R)-3-(chloromethyl)-7-[[(2Z)-2-[2-methyl-1-[(2-methylpropan-2-yl)oxy]-1-oxopropan-2-yl]oxyimino-2-[5-[(2-methylpropan-2-yl)oxycarbonylamino]-1,2,4-thiadiazol-3-yl]acetyl]amino]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate

Participants

Reaction Steps

A mixture of N,N-dimethylformamide (0.648 ml) and phosphoryl chloride (0.781 ml) was stirred at room temperature for 30 minutes. To the mixture were added tetrahydrofuran (4 ml) and (Z)-2-{5-[(tert-butoxy carbonyl)amino]-1,2,4-thiadiazol-3-yl}[(2-tert-butoxy-1,1-dimethyl-2-oxoethoxy)imino]ethanoic acid (3 g) at 4° C., and the reaction mixture was stirred at room temperature for 1 hour. Meanwhile, a mixture of benzhydryl 7β-amino-3-chloromethyl-3-cephem-4-carboxylate hydrochloride (3 g) and N-trimethylsilylacetamide (8.72 g) in tetrahydrofuran (15 ml) was warmed to make a clear solution. The solution was then cooled to −20° C. and added to the activated acid solution obtained above. The reaction mixture was stirred at a temperature of −10° C. to 0° C. for 1 hour and poured into a mixture of ethyl acetate and water. The aqueous layer was separated, and the organic layer was washed with brine, dried over anhydrous magnesium sulfate and filtered. The filtrate was concentrated in vacuo and purified by column chromatography on silica gel eluting with hexane/ethyl acetate (3:2) to give benzhydryl 7β-[(Z)-2-(5-tert-butoxycarbonylamino-1,2,4-thiadiazol-3-yl)-2-(1-tert-butoxycarbonyl-1-methylethoxyimino)acetamido]-3-chloromethyl-3-cephem-4-carboxylate (4.79 g).

Provenance & Evidence