DIAZEPINES .11. 6-HALOGENO-2,3-DIHYDRO-1H-1,4-DIAZEPINES

2,3-Dihydro-1H,1,4-diazepines are normally brominated at the 6-position. Phenyl substituents are usually unaffected, although with 2,3-dihydro-1,4- diphenyl-5,7-dimethyl-1H-1,4-diazepinium salts, the benzene rings are also brominated. 2,3-Dihydro-1,7-dimethyl-5-phenyl-1H-1,4-diazepine is brominated at the 7-methyl group. N-Chlorosuccinimide and N-iodosuccinimide also substitute dihydrodiazepines at the 6-position. Under appropriate conditions 6,6-dihalogenodihydro-6H-diazepines have been isolated, but they revert to monohalogeno-compounds in dilute hydrobromic acid. 6-Bromodihydro-1H-diazepinium salts are denominated by strong acid in the presence of bromide ion. With nucleophiles, 6-bromodihydro-1H-diazepines either undergo normal nucleophilic substitution or suffer replacement of the bromine by hydrogen.