Trifluoroacetic acid → (6R)-7-[[(2Z)-2-(2-amino-1,3-thiazol-4-yl)-2-methoxyiminoacetyl]amino]-3-[(2-carboxy-[1,3]thiazolo[4,5-c]pyridin-5-ium-5-yl)methyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate

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Reaction Steps

A mixture of diphenylmethyl 7-[(Z)-2-methoxyimino-2-(2-tritylaminothiazol-4-yl)acetamido]-3-iodomethyl-3-cephem-4-carboxylate [VIIa] (466 mg, 0.5 mmole) and 2-carboxythiazolo[4,5-c]pyridine [prepared according to the procedure of Zhur. Obshchei Khim., 26, 613 (1956); C.A., 50, 13906 (1956)] (90 mg, 0.5 mmole) in 2 ml of DMSO was stirred at room temperature for 1.5 hours and diluted with ethyl acetate-ether to give 375 mg of crude quaternary salt, which was treated with 5 ml of TFA and 0.1 ml of anisole at room temperature for 15 minutes. The mixture was evaporated in vacuo and triturated with ether to give 213 mg of crude Iv. The crude product was dissolved into a small volume of phosphate buffer (pH 7.0) and chromatographed on a column of packing (20 ml) in PrepPAK/C18 cartridge. The column was eluted with water (200 ml) and 10% aqueous CH3OH (150 ml) to afford 51 mg (17%) of the title compound (Iv) as an amorphous powder. Mp. 144°~160° C. (dec.). Estimated purity by HPLC: 85%.

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