Dmitriy V. Khakimov

Generation and metathesis of azomethine imines in reaction of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes with het(aryl)methylidenemalononitriles

A new metathesis reaction of azomethine imines is found. Catalytic or thermal diaziridine ring opening of 6-aryl-1,5-diazabicyclo[3.1.0]hexanes leads to azomethine imines reacting further with het(aryl)methylidenemalononitriles to give in situ new azomethine imines inaccessible by common synthetic methods. New azomethine imines are detected as pyrazolines formed via a 1,4-H shift and trapped by the [3+2] cycloaddition with various dipolarophiles to yield 1,5-diazabicyclo[3.3.0]octane derivatives bearing pharmacophoric heterocycles, e.g. furan, nitrofuran, thiophene, and indole. The best results are achieved in the Et2O·BF3-catalyzed reactions in ionic liquids.

Dinitrofuroxan cycloreversion as a novel general approach for the synthesis of nitroazoles

A novel general approach towards various nitroazoles via tandem process involving dinitrofuroxan cycloreversion followed by [3+2] cycloaddition of generated in situ nitroformonitrile oxide is developed. The reaction is promoted by addition of catalytic amounts of ionic liquids. Plausible mechanisms of the described processes based on quantum chemical calculations are proposed.

Quantum-chemical study of the reactivity of di- and trinitropyrazoles

Quantum chemistry methods (DFT B3LYP/6-31G* (3-21G)) were used to calculate the three-dimensional and electronic structure of 4-chloro-3,5-dinitro- and 3,4,5-trinitropyrazoles, as well as their model σ-complexes. Possible reasons for the peculiar reactivity of 3,4,5-trinitropyrazole, 4-chloro-3,5-dinitropyrazole, and their derivatives were examined.

Quantum chemical modeling of the enthalpy of formation for guanidinium bitetrazole salts

The enthalpies of formation for bitetrazole guanidinium salts in the gas and solid phases were calculated using the standard approach and isodesmic reaction method. A comparative analysis of the quality of the methods and the basis sets (HF, 3-21G, 6-31G, 6-311++G(d, p); DFT/B3LYP, 3-21G, 6-31G(d)) was performed for the calculation of the molecular volumes necessary for modeling the enthalpies of formation in solid phase, and the optimum set was recommended. The calculated values of enthalpies of formation of the compounds obtained by the isodesmic reaction method are three times lower than the results obtained using standard procedures.

The study of the formation mechanism of 1,2,3-trialkyldiaziridines by kinetic and quantum chemistry methods

Using UV spectrometry, we studied for the first time the regularities of AlkNHBr consumption in two variations of the formation of 1,2,3-trialkyldiaziridines in aqueous media: by mixing acetaldehyde and AlkNHBr in excess of AlkNH2 (method 1) and by the reaction of MeCH=NEt with EtNHBr in excess of EtNH2 (method 2). We determined the rate constants of the individual stages of the reaction. Using quantum chemistry methods (DFT/B3LYP/3-21G), we performed calculations of spatial and electronic structures of the reacting compounds, indices of local reactivity, and global electrophilicity of atoms of the individual reaction intermediates, based on which we explained the decrease in the reaction rate when using EtNHBr instead of MeNHBr in method 1. In method 2, the formation of 1,2-diethyl-3-methyldiaziridine occurs exclusively through the intermediate iminium cation.