Triethylamine → 9-Chloro-1-(2,4-dichlorophenyl)-6-[(ethylsulfanyl)methyl]-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazole

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Reaction Steps

To a solution of [9-chloro-1-(2,4-dichlorophenyl)-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazol-6-yl]methanol (300 mg, 0.784 mmol) and N,N-dimethylformamide (1 drop) in tetrahydrofuran (10 mL) was added thionyl chloride (0.086 mL, 1.18 mmol) at room temperature. The mixture was stirred at room temperature for 2 h. The mixture was concentrated in vacuo. To a solution of the residue in tetrahydrofuran (10 mL) and 2-propanol (10 mL) were added triethylamine (0.5 mL, 3.58 mmol) and sodium ethanethiolate (79.1 mg, 0.94 mmol) at room temperature. The mixture was stirred at 60° C. for 3 days. Sodium ethanethiolate (79.1 mg, 0.94 mmol) was added to the reaction mixture at room temperature and the mixture was stirred at 60° C. for 4 days. Water was added to the reaction mixture at room temperature and the mixture was extracted with ethyl acetate. The organic layer was washed with brine, dried over anhydrous magnesium sulfate, and concentrated in vacuo. The residue was purified by flash chromatography on NH-silica gel eluting with a 10-40% ethyl acetate/n-hexane gradient mixture to give the title compound (216 mg, 0.506 mmol, 65%) as a colorless amorphous.

Provenance & Evidence