Tributylphosphine → 9-Chloro-6-[cyclopropyl(2,2-difluoroethoxy)methyl]-1-(2,4-dichlorophenyl)-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazole

Participants

Reaction Steps

To a solution of [9-chloro-1-(2,4-dichlorophenyl)-1,2,3,4-tetrahydropyrimido[1,2-a]benzimidazol-6-yl](cyclopropyl)methanol (183 mg, 0.433 mmol), 1,1′-(azodicarbonyl)dipiperidine (219 mg, 0.868 mmol) in tetrahydrofuran (5.0 mL) was added tri(n-butyl)phosphine (0.217 mL, 0.869 mmol) at room temperature. After the mixture was stirred at room temperature for 10 min under nitrogen atmosphere, 2,2-difluoroethanol (0.272 mL, 4.30 mmol) was added to the reaction mixture. The mixture was stirred at 50° C. for 14 hr under nitrogen atmosphere. The mixture was concentrated in vacuo and diethyl ether was added to the residue. The solid was removed by filtration and the filtrate was concentrated in vacuo. The residue was purified by flash chromatography on silica gel eluting with a 10-40% ethyl acetate/n-hexane gradient mixture and recrystallization from 2-propanol/n-hexane to give the title compound (102 mg, 0.21 mmol, 48%) as colorless crystals.

Provenance & Evidence