Denis S. Baranov

An Unexpected Rearrangement That Disassembles Alkyne Moiety Through Formal Nitrogen Atom Insertion between Two Acetylenic Carbons and Related Cascade Transformations: New Approach to Sampangine Derivatives and Polycyclic Aromatic Amides

This work analyzes multiple new reaction pathways which originate from intramolecular reactions of activated alkynes with the appropriately positioned multifunctional hemiaminal moiety. Combination of experimental substituent effects with Natural Bond Orbital (NBO) analysis revealed that alkyne polarization controls partitioning between these cascades. A particularly remarkable transformation leads to the formation of six new bonds at the two alkyne carbons due to complete disassembly of the alkyne moiety and formal insertion of a nitrogen atom between the two acetylenic carbons of the reactant. This reaction offers a new synthetic approach for the preparation of polycyclic aromatic amides with a number of possible applications in molecular electronics. Another of the newly discovered cascades opens access to substituted analogues of Sampangine alkaloids which are known for their antifungal and antimycobacterial activity against AIDS-related opportunistic infection pathogens.

Urea as an organic solvent and reagent for the addition/cyclization/fragmentation cascades leading to 2-R-7H-dibenzo[de,h]quinolin-7-one analogues of Aporphinoid alkaloids

Molten urea serves both as a solvent and a reagent for the one-pot addition/cyclizations/fragmentation cascade which converts peri-alkynyl-9,10-anthraquinones into 2-R-7H-dibenzo[de,h]quinolin-7-ones – substituted analogues of Aporphinoid alkaloids.

Conformational Flexibility of Fused Tetracenedione Propellers Obtained from One-Pot Reductive Dimerization of Acetylenic Quinones

Reductive dimerization of acetylenic anthraquinones provides synthetic access to flexible nonplanar polyaromatics with a tetracenedione core. In solution, these nonplanar, contorted polycycles exist as equilibrating mixtures of two symmetric conformers. The fused tetracenediones are easily reduced and exhibit rich electrochemical behavior.

Novel Anthrathiophene-Based Small Molecules as Donor Material for Organic Photovoltaics: Synthesis and Light-Induced EPR Study

Abstract A novel anthrathiophene-based compound, 1,4-bis((5-(6,11-dioxoanthra[2,1-b]thiophene-2-yl)thien-2-yl)ethynyl)-2,5-bis(octyloxy)benzene, was synthesized and characterized. The optical absorption spectrum of the synthesized compound in film is strongly red-shifted as compared to the solution spectrum. The energies of frontier orbitals measured by cyclic voltammetry show that this compound can act as electron donor in a composite with the widely used fullerene derivative PCBM. This is confirmed by light-induced electron transfer from it to PCBM evidenced from light-induced EPR spectroscopy. The spectroscopic data suggest that anthrathiophene is a promising platform for synthesis of small-molecular electron donors for organic solar cells.

Full Cleavage of C≡C Bond in Electron-Deficient Alkynes via Reaction with Ethylenediamine

Reaction of 1,2-diaminioethane (ethylenediamine) with electron-deficient alkynes leads to full scission of the C≡C bond even in the absence of a keto group directly attached to the alkyne. This process involves oxidation of one of the alkyne carbons into C2 of a 2-R-4,5-dihydroimidazole with the concomitant reduction of the other carbon to a methyl group. The sequence of Sonogashira coupling with the ethylenediamine-mediated fragmentation described in this work can be used for selective formal substitution of halogen in aryl halides by a methyl group or a 4,5-dihydroimidazol-2-yl moiety.

The synthesis and anti-inflammatory activity of propargylamino derivatives of naphthoquinonlevopimaric acid

Naphthoquinonlevopimaric acid was modified with propargylamino residues and anti-inflammatory activities of the synthesized Mannich bases was studied.