Phosgene → [6-chloro-5-(o-fluorophenyl)-2,3-dihydro-1,3,3-trimethyl-2-oxo-1H-1,4-benzodiazepin-7-yl]isocyanate

Participants

Reaction Steps

A solution of 3.5 g (0.01 mol) of 7-amino-6-chloro-5-(o-fluorophenyl)-1,3-dihydro-1,3,3-trimethyl-2H-1,4-benzodiazepin-2-one in 60 ml of 1,2-dichloroethane is added dropwise while stirring to a solution of 1.5 g (0.015 mol) of phosgene in ice-cooled 1,2-dichloroethane so that the reaction temperature does not exceed 10°. Subsequently, the reaction mixture is heated at reflux while stirring for a further 10 minutes, whereupon it is cooled to ca 10° and made basic with triethylamine. There is thus obtained a solution of [6-chloro-5-(o-fluorophenyl)-2,3-dihydro-1,3,3-trimethyl-2-oxo-1H-1,4-benzodiazepin-7-yl]isocyanate which can be stored in the cold for several hours with the exclusion of moisture. It is further processed without isolation of the isocyanate contained therein.

Provenance & Evidence