86 mg (0.70 mmol) of 4-N,N-dimethylaminopyridine and 671 mg (3.50 mmol) of EDC were added to a solution of 550 mg (1.17 mmol) of the compound from Example 1 and 361 mg (3.50 mmol) of N,N-dimethylglycine in 11 ml of dichloromethane. After the reaction mixture had been stirred at RT for 8 h, all volatile constituents were removed on a rotary evaporator. The residue obtained was taken up in 200 ml of ethyl acetate and washed once with approx. 100 ml of water. After drying over anhydrous magnesium sulphate, filtration and concentration, the product was isolated by means of MPLC (approx. 30 g of silica gel, eluent: 25:25:1 cyclohexane/ethyl acetate/triethylamine) A first fraction of 328 mg of the title compound was obtained. A further 115 mg of the title compound were obtained from a second, still-contaminated fraction by recrystallization from cyclopentyl methyl ether. A total of 443 mg (68% of theory) of the title compound was thus obtained. Another crystallization from diisopropyl ether/cyclopentyl methyl ether (2:1, 1.5 ml per 100 mg) gave the title compound with a melting point of 117° C.
