1
|
Eder J, Antonov AS, Tupikina EY, Gschwind RM. Chiral Diselenophosphoric Acids for Ion Pair Catalysis: A Novel Approach to Enhance Both Proton Donating and Proton Accepting Properties. Chemistry 2024; 30:e202401793. [PMID: 38747423 DOI: 10.1002/chem.202401793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Indexed: 07/18/2024]
Abstract
The activation of poorly reactive substrates via strong chiral acids is a central topic in asymmetric ion pair catalysis these days. Despite highly successful scaffolds such as N-triflylphosphoramides, these catalysts either lack C2-symmetry or provide multiple H-bond acceptor sites, leading to lower ee values for certain reactions. We present BINOL-based diselenophosphoric acids (DSA) as an extremely promising alternative. Using an intertwined approach of synthesis and NMR studies, we developed a synthetic approach to DSA with up to 98 % NMR yield. The obtained acids provide both very high proton donor and proton acceptor properties, a bifunctionality, which is key to catalytic applications. Indeed, first reactivity test proved the much higher acidity of DSA and its ability to initiate Mukaiyama-Mannich reaction and protodesilylation of silyl ethers. Together with their C2-symmetry, the single donor and single acceptor situation, the decreased tendency of self-association, and the straightforward synthesis with potential 3,3'-substitution, the DSA provide all features ideal for the further development of ion pair catalysis.
Collapse
|
2
|
Antonov AS, Shpak IM, Ustinov DV, Izhberdeeva MP, Guseva AN, Galkina AY, Borodai NV, Udovichenko SK, Toporkov AV. Phylogenetic analysis and molecular genetic characteristics of West Nile virus lineage 2 isolates circulating in the Russian Federation. Virus Genes 2024; 60:370-376. [PMID: 38847934 DOI: 10.1007/s11262-024-02079-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 05/21/2024] [Indexed: 07/13/2024]
Abstract
Since its initial detection in Africa, the West Nile virus has disseminated widely across all continents, becoming endemic in numerous countries, including the Russian Federation. A substantial expansion of the West Nile virus range was observed in the European part of the Russian territory in 1999. In light of this epidemiological trend, research endeavours focusing on monitoring West Nile virus circulation activity in endemic regions of the country have gained paramount significance. A substantial dataset has been accrued from 2007 onwards regarding genomic variability and dissemination dynamics across the country throughout the entire monitoring period for the West Nile fever pathogen. The objective of this study was to characterise West Nile virus isolates that have been circulating in the Russian Federation and identify their molecular and genetic characteristics. A phylogenetic analysis of 55 complete genome sequences revealed that the West Nile virus population within the Russian Federation is genetically heterogeneous and is represented by four major clades. One of these clades is currently exhibiting extensive spread into new regions of the country.
Collapse
|
3
|
Meshalkin SA, Tsybulin SV, Bardakov VG, Tatarinov IA, Shitov DA, Tupikina EY, Efremova MM, Antonov AS. "Buttressing Effect" in the Halogen-Lithium Exchange in ortho-Bromo-N,N-dimethylanilines and Related Naphthalenes. Chemistry 2024; 30:e202303956. [PMID: 38131216 DOI: 10.1002/chem.202303956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 12/23/2023]
Abstract
Non-covalent interactions such as coordination of an organolithium reagent by a directing group and steric repulsion of substituents strongly affect the halogen-lithium exchange process. Here we present the manifestation of the "buttressing effect" - an indirect interaction between two substituents issued by the presence of a third group - and its influence on the ease and selectivity of the bromine-lithium exchange and the reactivity of formed aryllithiums. The increase of the size of the "buttressing" substituent strongly affects the conformation of a NMe2 group, forcing it to hinder ortho-bromine and thus slowing down the exchange. In naphthalene substrates bearing two bromines, this suppresses regioselectivity of the reaction. The "buttressing effect" forces formed aryllithiums to deaggregate, thus boosting their reactivity. This facilitates the decomposition via protolisys by ethereal solvents even at low temperatures and in some cases initiates fast Wurtz-Fittig coupling.
Collapse
|
4
|
Tsybulin SV, Kaplanskiy MV, Antonov AS. Transition-Metal-Free Synthesis of 2-Substituted Benzo[cd]Indoles via the Reaction of 1-Halo-8-lithionaphthalenes with Nitriles. Chemistry 2024; 30:e202303768. [PMID: 38197193 DOI: 10.1002/chem.202303768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/09/2024] [Accepted: 01/10/2024] [Indexed: 01/11/2024]
Abstract
A simple and effective organolithium approach to the synthesis of 2-substituted benzo[cd]indoles from peri-dihalonaphthalenes and nitriles has been developed. The reaction proceeds via a surprisingly easy intramolecular aromatic nucleophilic substitution facilitated by the "clothespin effect". The discovered transformation provides good isolated yields, allows usage of an extensive range of nitriles, and demonstrates a good substituents tolerance. UV-absorption and NMR spectra of the obtained benzo[cd]indoles and their protonated forms demonstrated exclusive protonation to the indole nitrogen atom even in the presence of two NMe2 groups in positions 5 and 6 (i. e. "proton sponge" moiety).
Collapse
|
5
|
Kaplanskiy MV, Karpov VV, Tupikina EY, Antonov AS. NMR detection of the strained metallacycles in organolithiums: theoretical study. Org Biomol Chem 2024; 22:982-989. [PMID: 38180388 DOI: 10.1039/d3ob01916k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
For the first time through quantum chemistry methods, the effective use of 1JCLi spin-spin coupling constants as descriptors for assessing the formation of strained metallacycles is demonstrated. Both acyclic organolithiums and 3- to 7-membered metallacycles are examined. 80 organolithium compounds, including both monomeric and dimeric species, with ligands containing fluorine, nitrogen, oxygen, and carbon (in the form of carbanions), are tested. In general, the 1JCLi values below 12 Hz for monomeric species and below 6 Hz for dimeric species serve as clear indicators of strained monomeric metallacycle formation (for 6Li nuclei). The primary contributor to the overall 1JCLi value is the Fermi-contact term, which correlates directly with the carbon-lithium interatomic distance and allows to distinguish between dimers and monomers.
Collapse
|
6
|
Yakubenko AA, Tupikina EY, Antonov AS. The Role of Conjugation in the Halogen-Lithium Exchange Selectivity: Lithiation of 4,6,7,9-Tetrabromo-1,3-dimethyl-2,3-dihydro-1H-perimidine. Chemistry 2023; 29:e202301439. [PMID: 37261949 DOI: 10.1002/chem.202301439] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 05/31/2023] [Accepted: 06/01/2023] [Indexed: 06/03/2023]
Abstract
The first case of successful suppression of the coordination of a lithium atom with a dialkylamino group by the effective conjugation of the latter with the aromatic core has been discovered. This effect controls regioselectivity of the bromine-lithium exchange in 4,6,7,9-tetrabromo-1,3-dimethyl-2,3-dihydro-1H-perimidine, which leads to products with the most effective conjugation. As a result, the product of this quadruple exchange demonstrates no tendency of the coordination of the NMe groups to neighboring lithium atoms despite the absence of steric restrictions. Experimental results are explained by means of quantum chemical calculations: geometry optimization, natural bond analysis and scans using the modredundant scheme.
Collapse
|
7
|
Tolochenko DO, Tsybulin SV, Yakubenko AA, Tupikina EY, Antonov AS. Spontaneous Cyclization of peri-Diiminonaphthalenes Leading to the Formation of Benzo[ de]isoquinolines and Stable Benzo[ de]isoquinoliniums. Org Lett 2023; 25:977-981. [PMID: 36748976 DOI: 10.1021/acs.orglett.3c00035] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The interaction of peri-dilithionaphthalenes with organic cyanides was studied. Instead of the expected peri-diimines, the reaction leads to the formation of three types of benzo[de]isoquinolines. Treatment of unsubstituted 1,8-dilithionaphthalene with aromatic nitriles results in the formation of 1-amino-1,3-diaryl-1H-benzo[de]isoquinolines. In contrast, 4,5-dilithio-1,8-bis(dimethylamino)naphthalene gives an aromatic isoquinolonium cation via elimination of ammonia under the same condition. Upon treatment with tert-butylcyanide, both dilithionaphthalenes undergo a transformation to 1-amino-3,4-di-tert-butyl-4H-benzo[de]isoquinolines. The observed reactivity was supported by quantum chemical calculations.
Collapse
|
8
|
Marchenko AV, Ozeryanskii VA, Demidov OP, Antonov AS, Tupikina EY, Pozharskii AF. Organometallic Synthesis of 2,3,6,7-Tetrasubstituted 1,8-Bis(dimethylamino)naphthalenes for Investigation of the Double Buttressing Effect in Proton Sponges. J Org Chem 2022; 87:16506-16516. [DOI: 10.1021/acs.joc.2c02212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
9
|
Karpov VV, Antonov AS, Tupikina EY. Choice of computational protocol for carbon-lithium spin-spin coupling constants 1 J CLi. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2022; 60:985-995. [PMID: 35881390 DOI: 10.1002/mrc.5299] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/19/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
In this work, we tested various computational schemes for calculations of 1 JCLi constants with a high accuracy. On the example of six organolithium reagents (phenyllithium monomer and dimer, monomer s-butyllithium, monomers of 1- and 2-lithionaphthalenes, and a methyllithium tetramer), the following aspects are discussed: (i) the role of a model system geometry, (ii) influence of solvent effects, and (iii) the choice of a functional and basis set. Practical recommendations for calculation of 1 JCLi with an accuracy ±2 Hz are formulated.
Collapse
|
10
|
Mikshiev VY, Tolstoy PM, Puzyk AM, Kirichenko SO, Antonov AS. peri-Interactions in 1,8-bis(dimethylamino)naphthalene ortho-ketimine cations facilitate [1,5]-hydride shift: selective synthesis of 1,2,3,4-tetrahydrobenzo[ h]quinazolines. Org Biomol Chem 2022; 20:4559-4568. [PMID: 35593098 DOI: 10.1039/d2ob00674j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Selective heterocyclization leading to 1,2,3,4-tetrahydrobenzo[h]quinazolines from ortho-ketimines of 1,8-bis(dimethylamino)naphthalene (DmanIms) under acid catalysis has been revealed. In contrast to the rather unreactive N,N-dimethylaniline ortho-ketimine, DmanIms readily undergo this transformation without an additional catalyst. This distinction in the reactivity underscores the importance of the second peri-NMe2 group in DmanIms, which facilitates a [1,5]-hydride shift and the subsequent cyclization. The cascade of peri-interactions emerging between 1-NMe2 and 8-NMe2 groups has been identified as a reason for the catalytic effect: (1) the hydrogen bond in the DmanIm dication constrains 1-NMe2 in the desired position providing proximity of reaction centers, (2) the repulsion of the lone pairs of 8-NMe2 group and unrelaxed 1-NMe2 group arising right after deprotonation process reduces the Gibbs free energy of activation (ΔG‡) for the straight hydride shift, and (3) the electrostatic interaction between 8-NMe2 and the charged NCH2+ group in the intermediate increases the ΔG‡ for the reverse hydride shift.
Collapse
|
11
|
Bardakov VG, Yakubenko AA, Verkhov VA, Antonov AS. Organoboron Derivatives of 1,8-Bis(dimethylamino)naphthalene: Synthesis, Structure, Stability, and Reactivity. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
12
|
Yakubenko AA, Puzyk AM, Korostelev VO, Mulloyarova VV, Tupikina EY, Tolstoy PM, Antonov AS. Self-association of diphenylpnictoginic acids in solution and solid state: covalent vs. hydrogen bonding. Phys Chem Chem Phys 2022; 24:7882-7892. [PMID: 35302575 DOI: 10.1039/d2cp00286h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Triphenylpnictogens were oxidized to access diphenylpnictioginic acids Ph2XOOH (X = P, As, Sb, Bi). It was shown that oxidation with chloramine-T does not lead to the cleavage of a C-pnictogen bond. The preliminary reductive cleavage with sodium in liquid ammonia followed by the oxidation with hydrogen peroxide was successfully utilised for the synthesis of diphenylphosphinic and diphenylarsinic acids. It was shown that in solid state (by means of XRD), all diphenylpnictoginic acids form polymeric chains. Diphenylbismuthinic and diphenylantimonic acids form polymeric covalent adducts, while diphenylphosphinic and diphenylarsinic chains are associated through hydrogen bonding. Unlike diphenylphosphinic acid, diphenilarsinic acid forms two polymorphs of hydrogen-bonded infinite chains. In solution in a polar aprotic solvent diphenylarsinic acid, similarly to dimethylarsinic, forms hydrogen-bonded cyclic dimers together with a small amount of cyclic trimers.
Collapse
|
13
|
Yakubenko AA, Karpov VV, Tupikina EY, Antonov AS. Lithiation of 2,4,5,7-Tetrabromo-1,8-bis(dimethylamino)naphthalene: Peculiarities of Directing Groups’ Effects and the Possibility of Polymetalation. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00489] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
14
|
Mulloyarova VV, Puzyk AM, Efimova AA, Antonov AS, Evarestov RA, Aliyarova IS, Asfin RE, Tolstoy PM. Solid-state and solution-state self-association of dimethylarsinic acid: IR, NMR and theoretical study. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130176] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
15
|
Antonov AS, Tupikina EY, Karpov VV, Mulloyarova VV, Bardakov VG. Sterically Facilitated Intramolecular Nucleophilic NMe 2 Group Substitution in the Synthesis of Fused Isoxazoles: Theoretical Study. Molecules 2020; 25:molecules25245977. [PMID: 33348591 PMCID: PMC7765840 DOI: 10.3390/molecules25245977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 11/16/2022] Open
Abstract
The influence of steric repulsion between the NMe2 group and a second ortho-(peri-)substituent in the series of 1-dimethylaminonaphthalene and N,N-dimethylanilene ortho-oximes on the ease of the NMe2 group’s intramolecular nucleophilic substitution is studied. Possible reaction intermediates for three mechanisms are calculated (ωB97xd/def-2-TZVP), and their free Gibbs energies are compared to model reaction profiles. Supporting experiments have proved the absence of studied reactivity in the case of simple 2-dimethylaminobenzaldoxime, which allowed us to establish reactivity limits. The significant facilitation of NMe2 group displacement in the presence of bulky substituents is demonstrated. The possibility of fused isoxazoles synthesis via the intramolecular nucleophilic substitution of a protonated NMe2 group in the aniline and naphthalene series is predicted.
Collapse
|
16
|
Antonov AS, Karpov VV, Tupikina EY, Tolstoy PM, Vovk MA. Aggregation Behavior of Lithionaphthalenes in Solution: Experimental and Theoretical Study. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00524] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
17
|
Mikshiev VY, Pozharskii AF, Filarowski A, Novikov AS, Antonov AS, Tolstoy PM, Vovk MA, Khoroshilova OV. How Strong is Hydrogen Bonding to Amide Nitrogen? Chemphyschem 2020; 21:651-658. [PMID: 31953976 DOI: 10.1002/cphc.201901104] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 12/18/2019] [Indexed: 12/23/2022]
Abstract
The protonation of the carboxamide nitrogen atom is an essential part of in vivo and in vitro processes (cis-trans isomerization, amides hydrolysis etc). This phenomenon is well studied in geometrically strongly distorted amides, although there is little data concerning the protonation of undistorted amides. In the latter case, the participation of amide nitrogen in hydrogen bonding (which can be regarded as the incipient state of a proton transfer process) is less well-studied. Thus, it would be a worthy goal to investigate the enthalpy of this interaction. We prepared and investigated a set of peri-substituted naphthalenes containing the protonated dimethylamino group next to the amide nitrogen atom ("amide proton sponges"), which could serve as models for the study of an intramolecular hydrogen bond with the amide nitrogen atom. X-Ray analysis, NMR spectra, basicity values as well as quantum chemical calculations revealed the existence of a hydrogen bond with the amide nitrogen, that should be attributed to the borderline between moderate and weak intramolecular hydrogen bonds (2-7 kcal ⋅ mol-1 ).
Collapse
|
18
|
Tupikina EY, Denisov GS, Antonov AS, Tolstoy PM. Unusual behaviour of the spin-spin coupling constant 1J CH upon formation of CHX hydrogen bond. Phys Chem Chem Phys 2020; 22:1994-2000. [PMID: 31915781 DOI: 10.1039/c9cp05964d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
One-bond coupling constants 1JXY are usually used as a measure of the corresponding XY interatomic distances. However, the physical nature of this correlation is not well understood and, in some cases, a counterintuitive behaviour of 1JXY upon hydrogen bonded complex formation has been reported. In this work, the behavior of 1JCH upon formation and strengthening of complexes with CHX hydrogen bonds and upon a proton transfer process is investigated by means of 1H NMR spectroscopy and quantum chemical calculations. 1H NMR spectra of 1,1-dinitroethane solution at room temperature in various solvents (carbon tetrachloride, chloroform, dichloromethane, acetone, dimethylformamide and dimethyl sulfoxide) illustrate the increase of 1JCH by several Hz upon an increase of the complex strength. Computational results (MP2/aug-cc-pVDZ) reproduce this observation and allow one to conclude that the increase of 1JCH is mainly caused by the change of the carbon hybridization (an increase of s-character), rather than by the change in interatomic distance rCH. The behavior of 1JCH was also examined computationally for a wide range of CHX hydrogen bond energies and geometries. For this purpose, quantum-chemical modeling of the partial proton transfer process for complexes formed by 1,1-dinitroethane and trinitromethane as hydrogen bond donors with acetone, pyridine and fluoride anion as hydrogen bond acceptors was performed. The obtained results have confirmed the above-mentioned idea - for rather weak complexes, the dominant impact on the change of 1JCH magnitude is the increase of the s-character of carbon atom hybridization, while for complexes with a significantly transferred proton, the exponential decrease of the Fermi-contact term dominates.
Collapse
|
19
|
Antonov AS, Bardakov VG, Mulloyarova VV. Sterically facilitated meta-lithiation of arenes, containing electron-donating groups. J Organomet Chem 2020. [DOI: 10.1016/j.jorganchem.2019.121068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
20
|
Antonov AS, Yakubenko AA. Noncovalent Li···H Interaction in the Synthesis of peri-Disubstituted Naphthalene Proton Sponges. SYNTHESIS-STUTTGART 2019. [DOI: 10.1055/s-0039-1690230] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Noncovalent Li···H interaction was utilised as a tool for the second lithiation of 4-lithio-1,8-bis(dimethylamino)naphthalene with n-BuLi in the presence of TMEDA in hexane. Metallation proceeds with 100% selectivity in the second peri-position and with up to 90% yield. A series of 4,5-disubstituted derivatives of 1,8-bis(dimethylamino)naphthalene has been prepared in good to excellent yield after quenching the reaction mass with different electrophiles.
Collapse
|
21
|
Pozharskii AF, Ozeryanskii VA, Mikshiev VY, Chernyshev AV, Metelitsa AV, Antonov AS. Proton-induced fluorescence in modified quino[7,8-h]quinolines: dual sensing for protons and π-donors. Org Biomol Chem 2019; 17:8221-8233. [PMID: 31436774 DOI: 10.1039/c9ob01391a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis, as well as spectral, structural and photoluminescence properties of dipyrido[3,2-e:2',3'-h]acenaphthene 5 and quinazolino[7,8-h]quinazolines 6 as representatives of the bidentate -N[double bond, length as m-dash]/-N[double bond, length as m-dash] superbases, are reported. These nitrogen bases being more rigid (5) or π-extended (6) analogs of optically-mute quino[7,8-h]quinoline are both active in terms of fluorescence with quantum yields up to φ = 0.71-0.77. At the same time, their luminescence behavior is opposite to that of peri-NMe2/NMe2 naphthalene proton sponges and their hybrid NMe2/-N[double bond, length as m-dash] analogs. Although 5 and 6 exhibit visible region emission upon protonation, for the hybrid systems the fluorescence is manifested only for bases. The most remarkable observation is that the fluorescence of compound 5 can be switched on not only by means of organic or inorganic acids, but also through the formation of chelate complexes with such weak H-donors as water and primary alcohols. It was disclosed that water is present in the complex as a cluster comprising 8 interconnected H2O molecules. Overall, the studied compounds demonstrate a previously unobserved type of dual mode optical response, H-sensing (emission enhancement in 5 and 6 on protonation) and π-sensing (emission quenching in 5H+ and 6H+ on coordination with π-donors). This work seems to be an important contribution to areas such as chemosensorics, the creation of new ligands, hydrogen transfer and some other phenomena representing different types of supramolecular interactions.
Collapse
|
22
|
Antonov AS, Leshchenko EV, Zhuravleva OI, Dyshlovoy SA, von Amsberg G, Popov RS, Denisenko VA, Kirichuk NN, Afiyatullov SS. Naphto-Γ-pyrones from the marine-derived fungus Aspergillus foetidus. Nat Prod Res 2019; 35:131-134. [PMID: 31242774 DOI: 10.1080/14786419.2019.1610954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Nine naphto-γ-pyrones rubrofusarine B (1), TMC 256 A1 (2), fansecinones A (3) and B (4), aurasperones A (5), B (6) and F (7), dianhydro-aurasperone C (8) and asperpyrone B (9) were isolated from the marine-derived fungus Aspergillus foetidus KMM 4694. Their structures were established based on spectroscopic methods. The effect of the substances on viability and colony formation of human drug-resistant prostate cancer 22Rv1 cell was evaluated.
Collapse
|
23
|
Antonov AS, Pozharskii AF, Tolstoy PM, Filarowski A, Khoroshilova OV. 1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation. Beilstein J Org Chem 2018; 14:2940-2948. [PMID: 30546478 PMCID: PMC6278759 DOI: 10.3762/bjoc.14.273] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/15/2018] [Indexed: 11/26/2022] Open
Abstract
The structure and protonation behaviour of four ortho-arylketimines of 1,8-bis(dimethylamonio)naphthalene with a different number of methoxy groups in an aromatic substituent were investigated in solution by NMR (acetone, DMSO, MeCN), in solid state by X-ray analysis and in the gas phase by DFT calculations. Both mono- and diprotonated species were considered. It has been shown that E-isomers of neutral imines can be stabilised by an intramolecular C=N−H···OMe hydrogen bond with a neighbouring methoxy group. Electron-donating OMe groups dramatically increase the basicity of the imino nitrogen, forcing the latter to abstract a proton from the proton sponge moiety in monoprotonated forms. The participation of the out-inverted and protonated 1-NMe2 group in the Me2N−H···NH=C hydrogen bond is experimentally demonstrated. It was shown that the number and position of OMe groups in the aromatic substituents strongly affects the rate of the internal hindered rotation of the NH2+ fragment in dications.
Collapse
|
24
|
Mazurov AV, Vinogradov DV, Kabaeva NV, Antonova GN, Romanov YA, VIasik TN, Antonov AS, Smirnov VN. A Monoclonal Antibody, VM64, Reacts with a 130 kDa Glycoprotein Common to Platelets and Endothelial Cells: Heterogeneity in Antibody Binding to Human Aortic Endothelial Cells. Thromb Haemost 2018. [DOI: 10.1055/s-0038-1646445] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
SummaryA new monoclonal antibody (mAb), VM64, reacts with a common antigen on the surface of human platelets and vascular endothelial cells (EC). Under nonreduced conditions it recognized in immunoblotting a protein of 130 kDa both in platelets and EC. VM64 precipitated the same 130 kDa protein from the lysate of surface radioiodinated platelets. Electrophoretic mobility of this protein was not altered by reduction and differed from the bands precipitated by reference mAb against platelet glycoproteins (GP) Ia–IIa, Ib, IIb–IIIa and GMP130. VM64 binding to platelets and EC was specific and saturable. The number of binding sites on platelets was 9.9 ± 3.5 × 103 per platelet and on the surface of EC monolayer – 2.40 ± 0.32 × 106 per cell. VM64 also binds to platelets from Glanzmann's thrombasthenia patients which lack GPIIb–IIIa. VM64 did not affect platelet aggregation induced by ADP, collagen, thrombin and ristocetin. In the monolayers of EC from umbilical vein and human aorta, VM64 stained the area at the periphery of the cells adjacent to the cell-cell boundaries. In preconfluent cultures preferential staining was observed at the active leading margins of the cells. Unlike EC cultures from umbilical vein, where all cells were positively stained, in aortic EC cultures some unstained or poorly stained cells were constantly present, indicating a heterogeneity of EC population related to the expression of VM64 antigen. The biochemical characteristics of VM64 antigen, its presence both on platelets and EC and typical distribution on the surface of EC suggested that this antigen is identical to PECAM (CD31) protein.
Collapse
|
25
|
Antonov AS, Bardakov VG, Pozharskii AF, Vovk MA, Misharev AD. Laying the way to meta -functionalization of naphthalene proton sponge via the use of Schlosser's superbase. J Organomet Chem 2018. [DOI: 10.1016/j.jorganchem.2017.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|