A number of 6,7‐dihydroquinazolino[3,2‐a][1,5]benzodiazepin‐13(5H)‐ones were prepared utilizing the coupling of readily available 5‐acyl‐1,3,4,5‐tetrahydro‐2H‐1,5‐benzodiazepin‐2‐ones with 2‐nitrobenzoyl chloride followed by a reductive N‐heterocyclization. 3‐Methylsubstituted 1‐(2‐nitrobenzoyl)‐1,5‐benzodiazepinone derivatives did not cyclize under the reductive N‐heterocyclization conditions. The possible mechanism of this heterocyclization was discussed, and it was demonstrated that the hydroxylamine intermediate was the initiator of this reaction. To clarify the reasons of different reactivities of various 1,5‐benzodiazepine derivatives, the quantum‐chemical reactivity descriptors of the hydroxylamine intermediates were calculated and evaluated.

A series of new potential electron transfer mediators, 2-substituted 1,4-benzoquinone derivatives bearing an arylamino group with various substituents in o-, m- and p-positions of an aromatic ring were synthesised by adding a solution of aniline derivatives in aqueous acetic acid to an aqueous solution of 1,4-benzoquinone. The structure and properties of synthesised compounds were investigated by NMR spectroscopy methods in detail. The redox ability of 2-arylamino-1,4-benzoquinone derivatives has been estimated by calculations of quantum chemical structure– activity relationship (QSAR) descriptors within the framework of density functional theory.

A series of 1-aryl substituted dihydro-, 5-methyldihydro- and 6-methyl-dihydro-2,4(1H,3H)pyrimidinediones and their 2-thio analogues were obtained by reaction of the corresponding β-alanines or α-methyl- and β-methyl-β-alanines with urea or potassium thiocyanate. The reaction of N-(2,3- and 3,5-dimethylphenyl)-α-methyl-β-alanines with ethyl acetoacetate gave 1-(2,3- or 3,5-dimethylphenyl)-2,5-dimethyl-1,4,5,6-tetrahydro-4(1H)pyridones. The combined spectral data obtained by 1H-, 13C-, 1H/13C (HETCOR) NMR and IR provided useful information about the structure of the products synthesized in this work.

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A series of condensation products of 1-aryl-4-hydrazinecarbonyl-2-pyrrolidinones with acetone, 2,4-pentanedione, and aromatic aldehydes was obtained and identified by the combination of IR, mass and 1 H, 13 C NMR spectroscopy. The results of their structural studies by NMR spectroscopy are provided. It was ascertained that the presence of the NH group determines the existence of the mixtures of the Z/E-isomers of compounds under study. The availability of Z-isomer as a sterically favorable one was also verified by computer molecular modeling.The products of condensation of carbohydrazides with carbonylic compounds -hydrazones -and its ring-closure reactions are well known and have been thoroughly studied. Compounds of these types are important for both chemical and pharmacological purposes and show analgetic, antidepressive, and bactericidal activities [1]. 1-Aryl-substituted 4-carboxy-2-pyrrolidinones and their salts, esters, amides, and nitriles are plant growth stimulators [2]. The first nucleophilic reaction used in this work was hydrazinolysis of the ester function. Acid hydrazides 2a-c were prepared from the corresponding esters 1a-c and hydrazine monohydrate in refluxing 2-propanol (Scheme 1).Condensation of compounds 2a-c with acetone gave the corresponding isopropylidenehydrazinecarbonyl-2-pyrrolidinones 3a-c, and the one -2b with aromatic aldehydes -1-aryl-4-arylidenehydrazinecarbonyl-2-pyrrolidinones 5-9. 1-Aryl-4-[(3,5-dimethylpyrazol-1-yl)carbonyl]-2-pyrrolidinones 4a-c were synthesized by condensation of hydrazides 2a-c with 2,4-pentanedione in 2-propanol in the presence of a catalytic amount of hydrochloric acid.N-Substituted hydrazones 10-12 were obtained in good yields by alkylation of 1-aryl-4-arylidenehydrazinecarbonyl-1-pyrrolidinones 5, 6 and 8 with ethyl iodide in the presence of potassium hydroxide and potassium carbonate with excess of ethyl iodide without solvent.The structure of the studied compounds 3-12 was elucidated by the methods of IR, mass and 1 H, 13 C NMR spectroscopy. Because of the different nature of fragments of the molecules of the tentative compounds their structural features were mostly unfolded by 1 H, 13 C NMR spectroscopy. Investigation of such structural fragments revealed information concerning the relation between the effects of substituents, their steric arrangement, and the possibility to participate in hydrogen bonding and conjugation. The signals in the NMR spectra were assigned [3, 4] on the basis of chemical shift theory, multiplicities, signal intensities, and comparison with suitable model compounds. The assignment was confirmed by 13 C NMR APT spectra. The results obtained are given in Tables 2-5. The identification of aromatic carbons in the 13 C NMR spectra __________________________________________________________________________________________