1-Chloroethyl chloroformate → 5-(2-Chlorophenyl)-1,2,3,6-tetrahydropyridine hydrochloride

To a solution of the 5-(2-chlorophenyl)-1,2,3,6-tetrahydro-1-methylpyridine (5.9 g) in dichloromethane (60 ml) was added 1-chloroethyl chloroformate (5.1 ml) and the mixture was stirred for 2.5 h. The mixture was washed with water and a saturated aqueous sodium chloride solution, and dried over anhydrous magnesium sulfate and the solvent was evaporated under reduced pressure to give brown oil. A solution of the obtained oil in methanol was refluxed for 2 h. The solvent was evaporated under reduced pressure and the obtained residue was crystallized from ethyl acetate to give 5-(2-chlorophenyl)-1,2,3,6-tetrahydropyridine hydrochloride (2.4 g). A solution of 5-(2-chlorophenyl)-1,2,3,6-tetrahydropyridine hydrochloride (155 mg), 2-chloro-1,6-dihydro-1-methyl-6-oxo-4-(pyrimidin-4-yl)pyrimidine (150 mg) and triethylamine (235 μl) in dimethylformamide (3 ml) was stirred at room temperature for 2 h. To the reaction mixture was added water (3 ml), and the precipitated crystals were collected by filtration to give the title compound (240 mg) as white crystals.