10-Membered Azaenediyne Fused to a Benzothiophene through the Nicholas Macrocyclization: Synthesis and DNA Cleavage Ability

Synlett ◽  
2018 ◽  
Vol 30 (02) ◽  
pp. 161-166 ◽  
Author(s):  
Irina Balova ◽  
Natalia Danilkina ◽  
Andrey Rumyantsev ◽  
Anna Lyapunova ◽  
Alexander D’yachenko ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Dna Cleavage ◽  
Functional Group ◽  
Analysis Data ◽  
Activation Energies ◽  
Efficient Technique ◽  
Bergman Cyclization ◽  
Dsc Analysis ◽  
Cleavage Assay ◽  
Pbr322 Plasmid

The Nicholas-type macrocyclization through NH-tosyl functional group has been found to be an efficient technique for the synthesis of a 10-membered azaenediyne system annulated with a benzothiophene. To compare the activity of azaenediyne synthesized with similar oxa- and carbocyclic enediynes the Bergman cyclization activation energies and the ability of enediynes to cleave DNA (pBR322 plasmid) were investigated. The order of reactivity predicted by DFT calculations (N-enediyne < C-enediyne < O-enediyne) was confirmed by DSC analysis data. Surprisingly azaenediyne was found to be more active in the DNA cleavage assay than the C-analogue.

The Azidosulfonylation of Terminal Alkynes Leading to β-azidovinyl Sulfones

2021 ◽  
Author(s):  
Long Zheng ◽  
Zhanjing Wang ◽  
Chen Li ◽  
Yong Wu ◽  
Zhaohong Liu ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Functional Group ◽  
High Yield ◽  
Terminal Alkynes

We reported herein the first example of N3 radical-mediated azidosulfonylation of alkynes, affording the β-azidovinyl sulfone products in broad substrate scope, excellent functional group compatibility, and high yield. DFT calculations...

scholarly journals Sulfide (Na2S) and Polysulfide (Na2S2) Interacting with Doxycycline Produce/Scavenge Superoxide and Hydroxyl Radicals and Induce/Inhibit DNA Cleavage

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1148 ◽  
Author(s):  
Anton Misak ◽  
Lucia Kurakova ◽  
Eduard Goffa ◽  
Vlasta Brezova ◽  
Marian Grman ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydroxyl Radicals ◽  
Plasmid Dna ◽  
Dna Cleavage ◽  
Biological Effects ◽  
Antibacterial Treatment ◽  
Ros Production ◽  
Biological Processes ◽  
Oxygen Species ◽  
Cleavage Assay

Doxycycline (DOXY) is an antibiotic routinely prescribed in human and veterinary medicine for antibacterial treatment, but it has also numerous side effects that include oxidative stress, inflammation, cancer or hypoxia-induced injury. Endogenously produced hydrogen sulfide (H2S) and polysulfides affect similar biological processes, in which reactive oxygen species (ROS) play a role. Herein, we have studied the interaction of DOXY with H2S (Na2S) or polysulfides (Na2S2, Na2S3 and Na2S4) to gain insights into the biological effects of intermediates/products that they generate. To achieve this, UV-VIS, EPR spectroscopy and plasmid DNA (pDNA) cleavage assay were employed. Na2S or Na2S2 in a mixture with DOXY, depending on ratio, concentration and time, displayed bell-shape kinetics in terms of producing/scavenging superoxide and hydroxyl radicals and decomposing hydrogen peroxide. In contrast, the effects of individual compounds (except for Na2S2) were hardly observable. In addition, DOXY, as well as oxytetracycline and tetracycline, interacting with Na2S or other studied polysulfides reduced the •cPTIO radical. Tetracyclines induced pDNA cleavage in the presence of Na2S. Interestingly, they inhibited pDNA cleavage induced by other polysulfides. In conclusion, sulfide and polysulfides interacting with tetracyclines produce/scavenge free radicals, indicating a consequence for free radical biology under conditions of ROS production and tetracyclines administration.

Oxidative [4+2] Annulation of 1-Naphthols with Alkynes Accelerated by an Electron-Deficient Rhodium(III) Catalysts

2022 ◽  
Author(s):  
Antônio Junio Araujo Dias ◽  
Hiroto Takahashi ◽  
Juntaro Nogami ◽  
Yuki Nagashima ◽  
Ken Tanaka
Keyword(s):  
Dft Calculations ◽  
Activation Energies ◽  
High Efficacy ◽  
Mild Conditions ◽  
Internal Alkynes ◽  
Lower Activation

The 1,3-diethoxycarbonyl-2,4,5-trimethylcyclopentadienyl (CpE) rhodium(III) complex displayed high efficacy in the catalytic oxidative annulation of 1-naphthols with internal alkynes under mild conditions. DFT calculations revealed that lower activation energies for the...

Metal−Ligand Charge-Transfer-Promoted Photoelectronic Bergman Cyclization of Copper Metalloenediynes:  Photochemical DNA Cleavage via C-4‘ H-Atom Abstraction

2003 ◽  
Vol 125 (21) ◽  
pp. 6434-6446 ◽  
Author(s):  
Pedro J. Benites ◽  
Rebecca C. Holmberg ◽  
Diwan S. Rawat ◽  
Brian J. Kraft ◽  
Lee J. Klein ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Dna Cleavage ◽  
Bergman Cyclization ◽  
Ligand Charge Transfer ◽  
Metal Ligand

scholarly journals An aniline dication-like transition state in the Bamberger rearrangement

2013 ◽  
Vol 9 ◽  
pp. 1073-1082 ◽  
Author(s):  
Shinichi Yamabe ◽  
Guixiang Zeng ◽  
Wei Guan ◽  
Shigeyoshi Sakaki
Keyword(s):  
Activation Energy ◽  
Dft Calculations ◽  
Transition State ◽  
Water Cluster ◽  
Transition States ◽  
Activation Energies ◽  
Nitrenium Ion ◽  
Proton Transfers ◽  
First Time

A Bamberger rearrangement of N-phenylhydroxylamine, Ph–N(OH)H, to p-aminophenol was investigated by DFT calculations for the first time. The nitrenium ion, C6H5–NH+, suggested and seemingly established as an intermediate was calculated to be absent owing to the high nucleophilicity of the water cluster around it. First, a reaction of the monoprotonated system, Ph–N(OH)H + H3O+(H2O) n (n = 4 and 14) was examined. However, the rate-determining transition states involving proton transfers were calculated to have much larger activation energies than the experimental one. Second, a reaction of the diprotonated system, Ph–N(OH)H + (H3O+)2(H2O)13, was traced. An activation energy similar to the experimental one was obtained. A new mechanism of the rearrangement including the aniline dication-like transition state was proposed.

scholarly journals Visible light induced alkene aminopyridylation using N-aminopyridinium salts as bifunctional reagents

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yonghoon Moon ◽  
Bohyun Park ◽  
Inwon Kim ◽  
Gyumin Kang ◽  
Sanghoon Shin ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Electrostatic Interaction ◽  
Functional Group ◽  
Eosin Y ◽  
Pyridine Derivatives ◽  
Reaction Conditions ◽  
Radical Trapping ◽  
Molecular Complexity ◽  
Pyridinium Nitrogen ◽  
Mechanism Of The Reaction

Abstract The development of intermolecular alkene aminopyridylation has great potential for quickly increasing molecular complexity with two valuable groups. Here we report a strategy for the photocatalytic aminopyridylation of alkenes using a variety of N-aminopyridinium salts as both aminating and pyridylating reagents. Using Eosin Y as a photocatalyst, amino and pyridyl groups are simultaneously incorporated into alkenes, affording synthetically useful aminoethyl pyridine derivatives under mild reaction conditions. Remarkably, the C4-regioselectivity in radical trapping with N-aminopyridinium salt can be controlled by electrostatic interaction between the pyridinium nitrogen and sulfonyl group of β-amino radical. This transformation is characterized by a broad substrate scope, good functional group compatibility, and the utility of this transformation was further demonstrated by late-stage functionalization of complex biorelevant molecules. Combining experiments and DFT calculations on the mechanism of the reaction is investigated to propose a complete mechanism and regioselectivity.

The Non-Isothermal Crystallization Kinetics of Dispersible Nano-SiO2/PA66 Composites

2012 ◽  
Vol 535-537 ◽  
pp. 94-102
Author(s):  
Lei Jia ◽  
Li Ping Guo ◽  
Xiang Min Xu
Keyword(s):  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Activation Energies ◽  
Crystallization Time ◽  
Dsc Analysis ◽  
Screw Extruder ◽  
Isothermal Crystallization Kinetics ◽  
Melt Compounding ◽  
Twin Screw ◽  
Kinetics Of

The PA66-based composites containing dispersible nano-SiO2 (DNS) were prepared in a twin-screw extruder by melt compounding. The microstructures of dispersible nano-SiO2/PA66 composites were investigated by means of TEM and XRD, and the non-isothermal crystallization behavior was studied through Jeziorny method and Mo method based on DSC analysis. The results showed that the dispersion of DNS was uniform in PA66 matrix, which could be related to surface structure of dispersible nano-SiO2. It was found from the study of the non-isothermal crystallization kinetics that dispersible nano-SiO2 possessed a heterogeneous nucleation capability in PA66 matrix, and its addition could hinder the motion of PA66 molecular chain, lower the crystallization temperature, and prolong the crystallization time of PA66. In addition, the activation energies for non-isothermal crystallization of neat PA66 and composites were also evaluated by the Kissinger method. The result showed that the activation energies of dispersible nano-SiO2/PA66 composites were higher than that of neat PA66.

DNA cleavage assay for the identification of topoisomerase I inhibitors

2008 ◽  
Vol 3 (11) ◽  
pp. 1736-1750 ◽  
Author(s):  
Thomas S Dexheimer ◽  
Yves Pommier
Keyword(s):  
Dna Cleavage ◽  
Topoisomerase I ◽  
Topoisomerase I Inhibitors ◽  
Cleavage Assay
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