0.430 g of 1-[5-(4-tert-butyl-piperazin-1-yl)pyridin-2-yl]-1,2,3,4-tetrahydroquinoxaline is put in 12.23 ml of dichloromethane and 0.51 ml of triethylamine, then 0.181 g of triphosgene is added at 0° C. The reaction mixture is stirred at room temperature under nitrogen atmosphere for 15 minutes to form 4-[5-(4-tert-butyl-piperazin-1-yl)pyridin-2-yl]-3,4-dihydro-2H-quinoxaline-1-carbonyl chloride. 0.378 g of trans N-(4-amino-adamantan-1-yl)-methanesulfonamide is prepared in 10 ml of dimethyl formamide and 0.51 ml of triethylamine under nitrogen atmosphere which is heated to dissolve it. The hot mixture is added to the reaction mixture containing 4-[5-(4-tert-butyl-piperazin-1-yl)pyridin-2-yl]-3,4-dihydro-2H-quinoxaline-1-carbonyl chloride and it is stirred for two hours. Water and sodium chloride are added, and it is extracted three times with dichloromethane; the organic phases are combined and then dried over magnesium sulfate, then concentrated under reduced pressure. The 0.829 g of raw product is chromatographed on silica gel, eluting with a gradient of a dichloromethane/(dichloromethane-methanol 90:10) mixture from 0 to 100%. 0.4184 g of trans (5-methanesulfonylamino-adamantan-2-yl)amide of 4-[5-(4-tert-butyl-piperazin-1-yl)pyridin-2-yl]-3,4-dihydro-2H-quinoxaline-1-carboxylic acid is obtained.
