Aminodihydrodiazepinium Salts

Nitro substituents in dihydrodiazepinium salts can be reduced by means of iron and acetic acid without reduction of the dihydrodiazepinium ring for example, p-aminophenyl-substituted dihydrodiazepinium salts have been obtained in this way.28 Although 6-nitro groups can also be reduced by metal and acid, it is not a satisfactory method for the preparation of 6-aminodihydrodiazepinium salts since the products apparently form complexes with the metal. 6-Amino derivatives are most conveniently prepared by catalytic reduction of the related nitro compound using either 

6-Aminodihydrodiazepinium salts are stable, but it has proved impossible to isolate the bases. The salts react readily with benzaldehydes to form stable anils which can be reduced to arylamino derivatives by sodium borohydride this reagent also does not react with the dihydrodiazepine ring 28,55 

Reaction of 6-aminodihydrodiazepinium salts with sodium nitrite and acid produced stable solids with peaks in their IR spectra at 2200 cm-1 characteristic of aromatic and heteroaromatic diazonium salts.28 64,55 These diazonium salts could be converted into 6-chlorodihydrodia-zepines.28,64,55 With alcohols or potassium iodide the diazonium group was replaced by a hydrogen atom in the latter case it is likely that a 6-iodo compound was formed which was then protodeiodinated in the acid conditions.54 

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Aminodihydrodiazepinium salts have been prepared by the reaction of ethylenediamine with oxazolium salts (76GP25125I0). 

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