SYNTHESIS AND STRUCTURE OF NEW DERIVATIVES OF 10-R-4-METHYL-1,8-DINITRO-3-OXA-5,10-DIAZATRICYCLO[6.3.1.02.6]DODECA-2(6),4-DIENE

Abstract

The spatial and electronic structure of 2-methyl-5,7-dinitrobenzo[d]oxazole, which is the substrate for the synthesis of hydride σ-adducts, was studied by the DFT/B3LYP/aug-cc-pVDZ method. Analysis of the charges on the atoms showed that the largest positive NBO charge is concentrated on the carbon atom C2 of the oxazole ring, while the carbon atoms C4 and C6 annelated benzene nucleus have the highest Mulliken charges both in the gas phase and in water. Thus, it has been established that a rigid base, a methoxide ion, is attached to the carbon atom C2, which is a hard reaction center, and a reaction with a soft base, a hydride ion, can also proceed through softer reaction centers — carbon atoms of the benzene ring C4 and C6. The bond lengths calculated by the quantum-chemical method are in good agreement with the experimental data obtained by X-ray diffraction, which confirms the correctness of the choice of the quantum-chemical calculation method. New derivatives of 3-azabicyclo [3.3.1]nonane have been synthesized by Mannich condensation of 2-methyl-5,7-dinitrobenzo[d]oxazole hydride σ-adduct with methylamine and β-aminopropanoic acid. This method is distinguished by relative simplicity, availability of reagents and allows under mild conditions to transfer from the aromatic system activated by nitro groups to 3-azabicyclo[3.3.1]nonane derivatives containing the nitro groups that are promising from the point of view of further functionalization. The structure of the compounds obtained was proved by IR, 1H-, 13C-, two-dimensional correlation NMR spectroscopy, as well as elemental analysis data. It was shown that the compounds obtained can serve as the basis for the creation of hybrid physiologically active compounds containing both a 3-azabicyclononane fragment and an oxazole cycle.