Triethylamine → Methyl 9-chloro-1-(2,6-dibromo-4-methoxyphenyl)-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazole-6-carboxylate

Participants

Reaction Conditions

Reaction Steps

A mixture of methyl 4-chloro-3-{[(2,6-dibromo-4-methoxyphenyl)carbamothioyl]amino}-2-[(3-hydroxypropyl)amino]benzoate (560 mg, 0.963 mmol), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (203 mg, 1.06 mmol) and triethylamine (0.148 mL, 1.06 mmol) in tetrahydrofuran (10 mL) was stirred at 50° C. for 2 hr. The reaction mixture was diluted with ethyl acetate, washed with water and brine, dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. To a mixture of residue and triethylamine (0.671 mL, 4.81 mmol) in tetrahydrofuran (10 mL) was added methanesulfonyl chloride (0.304 mL, 3.85 mmol) at 0° C. The resultant mixture was stirred at room temperature for 1 h and concentrated in vacuo. After N,N-dimethylformamide (10 mL) and potassium carbonate (1.33 g, 9.62 mmol) were added to the residue, the resultant mixture was stirred at 80° C. for 4 h, diluted with ethyl acetate, washed with water and brine, dried over anhydrous sodium sulfate, filtered and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel eluting with a 30-60% ethyl acetate/n-hexane gradient mixture to give the title compound as a brown solid (466 mg, 0.881 mmol, 91%).

Provenance & Evidence