Triphosgene → (R)-(-)-1-(2-oxo-5-cyclohexyl-1,3,4,5-tetrahydro-2H-1,5-benzodiazepin-3-yl)-3-(3-tert-butoxycarbonyl-4-methylphenyl)urea

Participants

Reaction Steps

Under ice-cooling, triphosgene (456 mg) was added to a solution of tert-butyl 2-methyl-5-aminobenzoate (850 mg) in anhydrous tetrahydrofuran (50 ml), triethylamine (1.85 ml) was added thereto five times each 0.37 ml over a 15 minutes after divided into five portions. After the mixture was stirred at room temperature for 5 minutes, (R)-(−)-2-oxo-3-amino-5-cyclohexyl-1,3,4,5-tetrahydro-2H-1,5-benzodiazepine (1.04 g) was added under ice-cooling. The resultant mixture was stirred at room temperature for one hour, the reaction mixture was poured into ice-water, and extracted with ethyl acetate. The organic layer was washed with saturated brine, dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure, crystals so precipitated were washed with diisopropyl ether, to thereby obtain 1.94 g of the title compound (Yield: 98%).

Provenance & Evidence