Under argon, 7.52 g (58.2 mmol) of N,N-diisopropylethylamine and 7.71 g (14.81 mmol) of PyBOP are added to 5.20 g (10.58 mmol) of 7-(cis-3,5-dimethylpiperazin-1-yl)-6-fluoro-8-methoxy-1-(2,2,2-trifluoroethyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid hydroformate (Example 31A) and 3.73 g (21.2 mmol) of 2,4-dichlorobenzylamine in 10.7 ml of dimethylformamide and the mixture is stirred at room temperature overnight. The reaction mixture is diluted with 1500 ml of ethyl acetate and washed three times with water. The combined aqueous phases are extracted once with ethyl acetate. The combined organic phases are washed with a saturated sodium chloride solution, dried over sodium sulfate and concentrated. The residue is stirred with 30 ml of acetonitrile. The solid is then collected by filtration and dried under high vacuum. 6.80 mg of the target compound are obtained as a cocrystallisate with 1 eq. of acetonitrile. For smaller quantities the residue after extraction can be purified by preparative HPLC (by one of the methods 5 to 8).
