Synthesis,Spectroscopic, and Dyeing Properties of New Azo and Bisazo Dyes Derived from 5‐Pyrazolones

This study is in continuation of our work related to 5‐pyrazolones aimed at synthesizing new heterocycles with dyeing and anticipated biological properties. Compounds 1 and 2 ; 1‐methyl‐ or 1‐(2,4‐dimethylphenyl)‐3‐phenyl‐1H‐pyrazol‐5(4H)‐one, 3 ; 1‐methyl‐5‐oxo‐3‐phenyl‐4,5‐dihydro‐1H‐pyrazole‐4‐carbaldehyde and 4 ; 2‐(1‐methyl‐5‐oxo‐3‐phenyl‐1H‐pyrazol‐4(5H)‐ylidene)‐3‐phenylthiazolidin‐5‐one were prepared and subjected to diazotation with aromatic amines and diamines. New azo ( 1a – c , 2a, b , 3a , b , 4a , c ) and bisazo dyes ( 2c , d , 4b ) were obtained, and their structures were confirmed by spectroscopic and analytical methods. In addition, UV–vis measurements, dyeing performance, and fastness tests were carried out for all compounds.     

Synthesis of new aryl(hetaryl)-substituted tandospirone analogues with potential anxiolytic activity via reductive Heck type hydroarylations

Tandospirone (I), developed as an anxiolytic drug, is an aryl-piperazine compound that binds to both 5-HT_1A and dopamine D4 receptors. Palladium-catalysed hydroarylation reactions of tandospirone analogues containing an oxygen bridge and 3-(trifluoromethyl)phenyl or 2,3-dichlorophenyl groups were studied in order to find a new stereoselective access to a series of new exo-aryl(hetaryl)-substituted derivatives with potential biological activity.     

Iron(III) selective fluorescence probe based on perylene tetracarboxylic diimide

Responses of organic fluorophore, perylenediimide derivative N,N′-di[3-[2-(3-thienyl)ethyl]phenyl]perylene-3,4,9,10-bis-(dicarboxyimide) (PDI1) was investigated in polymer matrix of polyvinyl chloride (PVC) by emission spectrometry. Its response to Fe(III) ions was evaluated in terms of the effect of pH. The properties of time dependent response, reversibility, limit of detection, linear concentration range for the metal ion and repeatability characteristics of the sensing element also have been studied. The offered sensor exhibited remarkable fluorescence intensity quenching at pH 6.0 in the concentration range of 1 × 10^?6 to 2.5 × 10^?3 M Fe(III) ions. The reproducibility of the sensor membrane was investigated by alternately changing the solution between 1 × 10^?4 M Fe(III) in Na₂HPO₄ (4 × 10^?2 M) and NaH₂PO₄ buffer (2 × 10^?3 M).     

Synthesis of new pyrazolothiazole derivatives from 4-thiazolidinones

The synthesis of new 2,3,5,6-aryl substituted tetrahydro-2H-pyrazolo[3,4-d]- thiazoles 4a-j as potential biologically active compounds by the cyclocondensation of phenyl hydrazine with new 5-arylidene derivatives 2a-j of 2,3-disubstituted-1,3- thiazolidin-4-ones 1a-e is reported.     

Thioxanthonation of fluorenone: Visible photoinitiator for radical polymerization

Thioxanthonation of fluorenone resulted in a new visible light initiator namely, indeno [1,2‐b]thioxanthene‐7,13‐dione (TX–FN). The detailed photophysical properties of the singlet and the triplet excited states of TX–FN are reported using steady‐state absorption, fluorescence, and phosphorescence, as well as laser flash photolysis techniques. Photoinitiated polymerization of MMA with TX–FN and CQ has been investigated in the presence and absence of a co‐initiator (MDEA). Additionally, Photo‐DSC studies were performed both in mono‐ and multiacrylate systems with TX–FN and parent compounds TX and FN. The obtained results were compared for formulations consisting of CQ. At low initiator concentrations, the conversions were lower than those obtained with TX–FN. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1012–1019     

The Synthesis of Epiboxidine and Related Analogues as Potential Pharmacological Agents

Methyl epiboxidine‐N‐carboxylate ( 8 ) was synthesized from 7 under reductive Heck conditions (Scheme 2). The C? C coupling of the new epiboxidine analog 9 with aryl and heteroaryl halides gave by hydroarylation C‐aryl, N‐(3‐methylisoxazol‐5‐yl)‐substituted tricyclic imides 10a – 10f (Table). The [3+2] cycloaddition of 9 with nitrile oxides yielded the bridged dihydroisoxazole derivatives 11a – 11d with potential biological activity (Scheme 4).     

A three-component,one-pot synthesis of 1,8-naphthyridine and isoxazole derivatives and computational elucidation of the mechanism

Research on Chemical Intermediates - An efficient and general method for the synthesis of substituted 3,4-dimethylisoxazolo[5,4-b]pyridine-5-carboxamide and benzo[b][1,8]naphthyridine-3-carboxamide...     

Imidazolidin-4-ones via (3+2) cycloadditions of aza-oxyallyl cations onto (E)-N-arylideneanilines

In the course of our studies on the chemistry of oxyallyl species we uncovered a new (3+2) cycloaddition of aza-oxyallyl systems, generated in situ from N-benzyloxy-2-chloroamides in the presence of NEt₃, onto N-arylimines yielding imidazolidin-4-ones in moderate to good yields. The cycloadditions are regioselective. Computational modeling using DFT at the M062x/6-311+G⁷ level is in support the observed regioselectivities. Although the path to the trans imidazolin-4-one is favored, the cis product is preferred by almost 8?kcal/mol and could be formed by base-catalyzed epimerization. All products were isolated by chromatography and characterized by means of their FTIR, NMR and HRMS data.     

Two and three positive solutions of m-point boundary value problems for functional dynamic equations on time scales

In this paper, by using fixed point theorems in a cone, we study the existence of at least two and three positive solutions of a nonlinear second-order m-point boundary value problem for functional dynamic equations on time scales. As an application, we also give an example to demonstrate our results.