Full Regio- and Stereoselective Protocol for the Synthesis of New Nicotinoids via Cycloaddition Processes with the Participation of Trans-Substituted Nitroethenes: Comprehensive Experimental and MEDT Study.

[3 + 2] Cycloaddition reactions with the participation of Z-C-(3-pyridyl)-N-methylnitrone and series of E-2-R-nitroethenes were both experimentally and theoretically explored in the framework of Molecular Electron Density Theory. It was found that all considered processes are realized under mild conditions and in full regio- and stereocontrol. The ELF analysis additionally showed that the studied reaction proceeds by a two-stage, one-step mechanism.

On the Question of the Formation of Nitro-Functionalized 2,4-Pyrazole Analogs on the Basis of Nitrylimine Molecular Systems and 3,3,3-Trichloro-1-Nitroprop-1-Ene.

Experimental and theoretical studies on the reaction between (E)-3,3,3-trichloro-1-nitroprop-1-ene and N-(4-bromophenyl)-C-arylnitrylimine were performed. It was found that the title process unexpectedly led to 1-(4-bromophenyl)-3-phenyl-5-nitropyrazole instead of the expected Δ2-pyrazoline molecular system. This was the result of a unique CHCl3 elimination process. The observed mechanism of transformation was explained in the framework of the molecular electron density theory (MEDT). The theoretical results showed that both of the possible channels of [3 + 2] cycloaddition were favorable from a kinetic point of view, due to which the creation of 1-(4-bromophenyl)-3-aryl-4-tricholomethyl-5-nitro-Δ2-pyrazoline was more probable. On the other hand, according to the experimental data, the presented reactions occurred with full regioselectivity.