2- and 2,7-Substituted para-N-Methylpyridinium Pyrenes: Syntheses,Molecular and Electronic Structures,Photophysical, Electrochemical,and Spectroelectrochemical Properties and Binding to Double-Stranded (ds) DNA

Two N-methylpyridinium compounds and analogous N-protonated salts of 2- and 2,7-substituted 4-pyridyl-pyrene compounds were synthesised and their crystal structures, photophysical properties both in solution and in the solid state, electrochemical and spectroelectrochemical properties were studied. Upon methylation or protonation, the emission maxima are significantly bathochromically shifted compared to the neutral compounds, although the absorption maxima remain almost unchanged. As a result, the cationic compounds show very large apparent Stokes shifts of up to 7200 cm⁻¹. The N-methylpyridinium compounds have a single reduction at ca. −1.5 V vs. Fc/Fc⁺ in MeCN. While the reduction process was reversible for the 2,7-disubstituted compound, it was irreversible for the mono-substituted one. Experimental findings are complemented by DFT and TD-DFT calculations. Furthermore, the N-methylpyridinium compounds show strong interactions with calf thymus (ct)-DNA, presumably by intercalation, which paves the way for further applications of these multi-functional compounds as potential DNA-bioactive agents.     

Utility of 2-(5-methyl-1-phenyl-1H-pyrazol-4-yl)-2-oxo-N′-phenylaceto-hydrazonoyl bromide as precursor for synthesis of new functionalized heterocycles

2-(5-Methyl-1-phenyl-1H-pyrazol-4-yl)-2-oxo-N′-phenylaceto-hydrazonoyl bromide was synthesized and used as precursor for synthesis of some new 1,3,4-thiadiazoles, pyrrolo[3,4-c]pyrazoles, and 1,2,4-triazolo[4,3-a]pyrimidines. The mechanisms that account for formation of products were discussed. Also, the structures of all the newly synthesized products were confirmed based on elemental analysis, spectral data and by alternative methods.     

Synthesis of Tetrazoloquinoline‐Based Mono‐ and Bisphosphonate Esters as Potent Anti‐Inflammatory Agents

Several new α‐alkoxy‐ and α‐hydroxyphosphonate derivatives of tetrazole‐quinolines were synthesized from the reaction of 2‐azidoquinolines 3‐carboxaldehyde 1a,b with trialkyl phosphites and dialkyl phosphites. On the other hand, azaphospholes 12a,b were obtained by treating 1a,b with tris(dimethylamino)phosphine. Furthermore, Perkin‐type condensation of 1a,b and tetraethyl methylenebisphosphonate provided the corresponding tetrazoloquinoline‐based bisphosphonate esters 14a,b . Based on the prediction results (PASS program), the anti‐inflammatory activity of the prepared compounds was determined in vivo by the acute carrageenin‐induced paw edema in rats. Many of the new compounds exhibit considerable anti‐inflammatory properties at a dose of 50 mg/kg body weight. Especially 14a and 14b revealed remarkable activities compared with indomethacin, which was used as a reference standard in this study.     

Photoisomerisation in Aminoazobenzene‐Substituted Ruthenium(II) Tris(bipyridine) Complexes: Influence of the Conjugation Pathway

Transition‐metal complexes containing stimuli‐responsive systems are attractive for applications in optical devices, photonic memory, photosensing, as well as luminescence imaging. Amongst them, photochromic metal complexes offer the possibility of combining the specific properties of the metal centre and the optical response of the photochromic group. The synthesis, the electrochemical properties and the photophysical characterisation of a series of donor–acceptor azobenzene derivatives that possess bipyridine groups connected to a 4‐dialkylaminoazobenzene moiety through various linkers are presented. DFT and TD‐DFT calculations were performed to complement the experimental findings and contribute to their interpretation. The position and nature of the linker (ethynyl, triazolyl, none) were engineered and shown to induce different electronic coupling between donor and acceptor in ligands and complexes. This in turn led to strong modulations in terms of photoisomerisation of the ligands and complexes.     

Access to New Endoperoxide Derivatives by Electrochemical Oxidation of Substituted 3‐Azabicyclo[4.1.0]hept‐4‐enes

A series of substituted 3‐azabicyclo[4.1.0]hept‐4‐ene derivatives were prepared and analysed by cyclic voltammetry. Preparative aerobic electrochemical oxidation reactions were then carried out. Three original endoperoxides were isolated, characterised and subjected to antimalarial and cytotoxicity activity assays.     

Synthesis of Fused Thioxo-Pyran Systems From α-Methylene Carbonyl Compounds and Bismethylene-1,3-dithietane

A number of [2, 1-b] fused phosphono substituted-thioxo-pyrans 7,10,13 and 18 have been regioselectively synthesised from the reaction of the corresponding α-methylene carbonyl compound with phosphenato-substituted 1,3-dithietane 1. Conversely, 2-thiohydantoin 14 reacts with 1 to afford the respective 4-substituted derivative 15.     

PHOTOCHEMISTRY OF PESTICIDES, 71. REGIOSELECTIVE PHOTODIMERIZATION OF o,o-DIETHYL-o-(3-CHLORO-4-METHYLCOUMARIN-7-YL)-THIOPHOSPHATE (COUMAPHOS)

Abstract

UV-irradiation (λ > 313 nm) of o,o-diethyl-o-(3-chloro-4-methyl-coumarin-7-yl)-thiophosphate (Coumaphos; 1) in chloroform results in an regioselective dimerization reaction to afford the head-to-tail anti-dimer 2. The structure of 2 is established by single crystal x-ray diffraction. Singlet oxygen does not affect the formation of 2.     

Regioselective Condensation of Alkylidenephosphoranes to N-Methoxy- and N-Anilino-1H isoindole-1,3-(2H)-diones

Treatment of 2-methoxyisoindoline-1,3-dione with resonance-stabilized alkylidenephosphoranes afforded the corresponding monoalkenes as the sole reaction product, in ～58–63% yields, whereas more than 80% yields of the same monoolefin products were obtained when the reactions were carried out under microwave conditions. Similarly, 2-(phenylamino)isoindoline-1,3-dione reacted under either thermal or microwave conditions to give only the corresponding monoalkene derivatives. The alkene products from both substrates were further reduced to the corresponding isoindoles using Zn-dust in EtOH. Prediction of the designed compounds and the in vivo anti-inflammation activity of the products in the rat adjuvant model were also studied. The work is the first demonstration of the anti-inflammatory activity of phthalimide derivatives.     

Reactions of Hydrazonoyl Halides 33 1 : Synthesis of Some New 2,3-Dihydro-1,3,4-thiadiazoles Containing Pyrazol-3-yl,Indolin-2-one-2-yl and Indan-1,3-dione-2-yl Moieties

Some new 2,3-dihydro-1,3,4-thiadiazoles containing pyrazol-3-yl, indolin-2-one-2-yl and indan-1,3-dione-2-yl moieties in a good yields obtained from the reaction of hydrazonoyl halides with thiocarbamate and carbodithioate in ethanolic triethylamine respectively. In contrast, pyrazolylthiourea reacts with hydrazonoyl halides under the same condition afford corresponding hydrazonoyl sulfide derivatives.