730 mg (2.4 mmol) of tert-butyl(6-chloro-3-propanoylpyridin-2-yl)carbamate (Example 23A) were initially charged in 7 ml of DMSO, and 512 mg (3.2 mmol) of N-Boc-ethylenediamine and 640 μl (3.7 mmol) of N,N-diisopropylethylamine were added. The reaction mixture was irradiated in the microwave reactor at 90° C. for 45 min. The reaction mixture was taken up in a mixture of ethyl acetate and water. The organic phase was washed with saturated aqueous ammonium chloride solution and then with saturated aqueous sodium bicarbonate solution, dried over magnesium sulfate and concentrated on a rotary evaporator. The reaction mixture was chromatographed on silica gel (mobile phase cyclohexane/ethyl acetate 5:1→1:1). This gave 530 mg (53% of theory) of the product as a solid.
