Phosgene → (S)-[6-bromo-5-(o-chlorophenyl)-2,3-dihydro-1,3-dimethyl-2-oxo-1H-1,4-benzodiazepin-7-yl]isocyanate

Participants

Reaction Steps

50 g (0.127 mol) of (S)-7-amino-6-bromo-5-(o-chlorophenyl)-1,3-dihydro-1,3-dimethyl-2H-1,4-benzodiazepin-2-one are dissolved in 700 ml of 1,2-dichloroethane while warming and the still hot solution is added dropwise while stirring and cooling to a mixture of 90 ml (0.173 mol) of a 20 percent solution of phosgene in toluene and 500 ml of dichloroethane in such a manner that the temperature does not exceed 10°. The mixture is subsequently heated to boiling under reflux while stirring for 1 hour, 500 ml of 1,2-dichloroethane are distilled off, the solution is cooled to 10°, made basic with triethylamine and evaporated, there being obtained (S)-[6-bromo-5-(o-chlorophenyl)-2,3-dihydro-1,3-dimethyl-2-oxo-1H-1,4-benzodiazepin-7-yl]isocyanate as a foam which can be stored for several days in a refrigerator with the exclusion of moisture.

Provenance & Evidence