Continuing our study of the synthesis of 3-acyl-l,5-diazepines through reaction of 2-acyicyclane-l,3diones with 1,2-diamines [I, 2] we have examined the reaction of 2-formyl-5,5-dimethylcyclohexane-l,3-diones (I) with 4-methyl-(lib), 4-benzoyi-(IIc), and 1,2-diamino-4-nitrobenzenes (IId). As shown in [2], the formylcyclanedione I and o-phenylenediamine (IIa) react in a molar ratio of 1 : 1 to give enamine IIIa. The presence of two non-equivalent amino groups in the starting diamines IIb-d makes the possible formation of two isomers in these reactions.Under experimental conditions for similar reactions (mixing of hot ethanolic solutions of the starting materials and subsequent recrystallization of the obtained product) only in the reaction of diamine lid is a single isomer formed and this is 2-(2-amino-5-nitrophenylaminomethylene)-5,5-dimethylcyclohexane-l,3-dione (IIId). In the case of diamines lib,c, a mixture is formed consisting of the main product which is enamine IIIb or IIIc and also the product of reaction at the second amino group, i.e., 2-(2-amino-5-methylphenylaminomethylene)-5,5dimethylcyclohexane-l,3-dione and 2-(2-amino-4-benzoylphenylaminomethylene)-5,5-dimethyicyclohexane-l,3dione respectively. The pure isomers IIIb,c could be prepared by treating formylcyclanedione I with diamines IIb,c at -20~ and precipitation of the products by aqueous potassium chloride solution.The structure of the obtained products was established through the analysis of spectral data. As has been shown in [1], in compounds of type III the most informative aspect of their PMR spectra is the chemical shift of the signal assigned to the aromatic proton situated in a meta position relative to the substituent (R or RZ). The shift of this signal depends on the way the amino groups in diamine II takes part in reaction with compound I. If the reacted amino group is situated meta to the substituent (R or R 1) the signal for this proton is shifted to high field relative to the signals of the other aromatic protons and is found in the region 6.84-6.86 ppm. In the opposite case, the signal is shifted to lower field (7.27 ppm) and does not differ significantly from those of the other aromatic protons. The observed shifts for the signals of compounds IIIc,d (6.79 and 6.80 ppm) unambiguously show that the