Under an N2 atmosphere, 160 mg (0.4 mmol) of 8-chloro-1-cyclopropyl-7-[(1S,6S)-2,8-diazabicyclo[4.3.0]non-8-yl]-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid are suspended in 2.25 ml of dichloromethane. 283 μl (1.6 mmol) of trimethylsilyltrifluoroacetamide are added and the mixture is stirred at room temperature for 20 minutes; 0.5 g of 3 Å molecular sieves is then added, and the mixture is stirred at room temperature for one hour, and the solution is evaporated to dryness. Subsequently, a solution of 151 mg (0.283 mmol) of benzhydryl [6R,7R]-3-chloromethyl-8-oxo-7-phenylacetylamino-5-thia-1-aza-bicyclo[4.2.0]oct-2-ene-2-carboxylate in 2.25 ml of acetone is added. After addition of 46.6 mg (0.367 mmol) of NaI, the mixture is stirred overnight (20 hours), poured into water, adjusted to pH=4 with 1N HCl, and extracted 3× with ethyl acetate. The organic phase is washed with water, dried over MgSO4 and evaporated to dryness. 96 mg (0.106 mmol) (38% of theory) of the title product are obtained by chromatography on silica gel using CH2Cl2 /CH3OH (30:1).
