Microwave-assisted,methanesulfonic acid-catalyzed synthesis of 3,3′-(arylmethylene)bis(4-hydroxy-2H-chromen-2-ones)

Efficient synthesis of 3,3′-(arylmethylene)bis(4-hydroxy-2H-chromen-2-ones) has been achieved by methanesulfonic acid-catalyzed, microwave-assisted reaction of 4-hydroxycoumarin and aromatic aldehydes in ethanol. The procedure has the advantages of high yield, short reaction time, low energy consumption, and convenient work-up. Compound structures were confirmed by IR, ¹H NMR, and ¹³C NMR spectroscopy and by elemental analysis.     

The composition and structure of polyvinyl butyral furfural: NMR study

With the use of ¹H NMR, ¹³C NMR and two-dimensional NMR spectroscopy, the composition and structure of polyvinyl butyral furfural samples obtained at different stages of poly(vinyl alcohol) acetalization have been determined. The structure of low-molecular-mass and oligomer admixtures that may be formed in the course of synthesis of the copolymer or during its dissolution in alcohol has been estimated via one-dimensional and two-dimensional diffusion NMR spectroscopy.     

KHSO4-mediated synthesis of α-amino phosphonates under a neat condition and their P NMR chemical shift assignments

A simple and efficient method for the synthesis of α-amino phosphonates has been accomplished from aromatic aldehydes, diethyl phosphite, and aromatic (or) aliphatic amines using potassium hydrogen sulfate as a catalyst under solvent free condition at ambient temperature and these compounds are characterized by ³¹P NMR with reference to H₃PO_4.     

Time‐Resolved In Situ MAS NMR Monitoring of the Nucleation and Growth of Zeolite BEA Catalysts under Hydrothermal Conditions

Time‐resolved ¹³C, ²³Na, ²⁷Al, and ²⁹Si MAS NMR has been applied in situ for monitoring the hydrothermal synthesis of zeolite BEA. Isotopic labelling with ²⁹Si and ¹³C isotopes has been used to follow the fate of siliceous species and structure directing agent ((¹³CH₃−CH₂)₄NOH). Two mechanistic pathways, namely solution‐mediated and solid–solid hydrogel rearrangement have been distinguished for two synthesis procedures studied. The mechanisms of structure‐directing behavior of TEA⁺ cations in two reaction pathways have been elucidated. The results show that multinuclear MAS NMR can serve as a superior tool for monitoring hydrothermal synthesis of various solids including zeolites, zeotypes, mesoporous materials, metal–organic frameworks and so on and for the design of novel outstanding materials for different applications.     

Iodo cyclofunctionalization of 2,4‐dialkenyl‐1,3‐dicarbonyl compounds: Synthesis of substituted 3‐(2‐furylidene)‐2‐furanones

A facile method for the synthesis of substituted 3‐(2‐furylidene)‐2‐furanones has been developed using cyclofunctionalization reactions of 2,4‐dialkenyl‐1,3‐dicarbonyl compounds and iodine as electrophile in the presence of Na₂CO₃, in refluxing chloroform. Compounds 4 are obtained in modest to good yields and their structural identification was established by ¹H NMR, ¹H COSY, ¹³C NMR and ¹H‐¹³C COSY. A mechanism has been proposed to rationalize the formation of the ylidene furanone.     

Facile One-Pot Method for the Synthesis of Novel N-Dichloroacetyl-1,3-oxazolidines

A short and efficient route to synthesis and structural characterization of a series of novel N-dichloroacetyl-5-ethyl-1,3-oxazolidine derivatives has been developed. These new compounds, characterized by the substitution at position 2 by alkyls, cycloalkanes, benzyls, or aryls, have been synthesized in good yields via a sequential procedure involving cycloaddition, condensation, and acylation. All the compounds are characterized by infrared, ¹H NMR, and ¹³C NMR.     

Synthesis of 4′-[3-methyl-5-thioxo-1H-1,2,4-triazol-4(5H)-yl]-2′,5′-diphenyl-2′,4′-dihydro spiro[indolin-3,3′[1,2,4]triazol]-2-one derivatives

In this paper 1,3-dipolar cycloaddition reaction has been studied. An efficient synthesis of 4′-[3-methyl-5-thioxo-1H-1,2,4-triazol-4(5H)-yl]-2′,5′-diphenyl-2′,4′-dihydro spiro(indolin-3,3′[1,2,4]triazol)-2-one derivatives using triethylamine in MeCN at room temperature is reported. The structures of the obtained compounds were confirmed by means of elemental analysis, MS and spectral (IR, ¹H, and ¹³C NMR) methods.     

The enhancement of luminescent properties of Tb3+ complexes with tetra-1,3-diketone ligands promoted by the tetrathiacalix[4]arene scaffold

This is the first report on the synthesis and characterization of tetra-1,3-diketone derivatives of tetrthia- and calix[4]arenes substituted by acetylacetonyl or dipivaloylmethanyl moieties at the upper rim and bearing hydroxyl groups at the lower rim as ligands for Tb³⁺ complexes. The spatial structure and tautomeric content for the synthesized ligands have been determined by means of X-ray, IR and NMR spectroscopy. Comparison of the sensitizing properties of tetrathiacalix[4]arenes and their calix[4]arene analogues on the Tb³⁺-centered luminescence in DMF solutions has been performed. A substantial enhancement of the luminescent properties of Tb³⁺- complexes with tetra-1,3-diketone ligands promoted by the tetrathiacalix[4]arene scaffold was established.     

Straightforward Hantzsch four‐ and three‐component condensation in the presence of triphenyl(propyl‐3‐sulfonyl)phosphoniumtrifluoromethanesulfonate {[TPPSP]OTf} as a reusable and green mild ionic liquid catalyst

Triphenyl(propyl‐3‐sulfonyl)phosphoniumtrifluoromethanesulfonate {[TPPSP]OTf} as a reusable, green and benign ionic liquid catalyst has been used in the Hantzsch four‐component (synthesis of polyhydroquinolines) and three‐component (synthesis of acridines) condensation reactions of 1,3‐diones, β‐ketoesters, aldehydes, ammonium acetate and aniline derivatives in the presence of 0.5 mol% of {[TPPSP]OTf} at room temperature under solvent‐free conditions. The new ionic liquid catalyst was fully characterized using infrared, ¹H NMR, ¹³C NMR, ³¹P NMR, ¹⁹F NMR and mass spectroscopies, and thermogravimetric and derivative thermogravimetric analyses. Additionally, the recovered catalyst can be recycled at least five times in subsequent reactions without significant loss in catalytic activity. The new synthesis technique presented offers numerous advantages of safety, mild conditions, simplicity, short reaction time, high yields and easy workup compared to the traditional synthesis method. Twenty products have been reported for the first time. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of new functionalized organoselenium compounds by heterocyclization of selenium dihalides with pent-4-en-1-ol

The reaction of selenium dihalides with pent-4-en-1-ol has been carried out for the first time. Efficient procedures for the synthesis of previously unknown bis(tetrahydrofuran-2-ylmethyl) selenide, dihalobis( tetrahydrofuran-2-ylmethyl)-λ⁴-selanes, and bis(tetrahydrofuran-2-ylmethyl) selenoxide have been developed on the basis of this reaction. The product structures have been studied by ¹H, ¹³C, and ⁷⁷Se NMR. Bis(tetrahydrofuran-2-ylmethyl) selenide and dihalobis(tetrahydrofuran-2-ylmethyl)-λ⁴-selanes represent equimolar mixtures of two diastereoisomers which display different signals in the ¹³C and ⁷⁷Se NMR spectra. The oxidation of bis(tetrahydrofuran-2-ylmethyl) selenide with sodium periodate in methanol leads to the corresponding selenoxide consisting of 4 diastereoisomers.     

Facile Synthesis of 4-Oxo-4H-quinolizine-2-carboxamide Derivatives

A facile synthetic method for the construction of 2-substituted-4-oxo-4H-quinolizine-based core structure has been successfully developed. The synthesis made use of a one-pot Stobbe condensation followed by cyclization starting from the commercially available 2-pyridinecarbaldehyde. The structure of the formed 4-oxo-4H-quinolizine-2-carboxylate was fully confirmed by mass spectra, ¹H NMR and ¹³C NMR, correlation spectrography, heteronuclear multiple bond correlation, and heteronuclear single quantum coherence (HSQC) spectra. The ethyl carboxylate moiety was then further functionalized via direct aminolysis by a range of amines to afford the corresponding 4-oxo-4H-quinolizine-2-carboxamides 4a–i in moderate to good yields.     

Synthesis of chiral calix[4]arenes bearing tartaric ester moieties

The synthesis of chiral calix[4]arenes with tartaric acid ester moieties has been achieved by the reactions of tartaric ester chloroacetates with calix[4]arenes in moderate yields. All the chiral calix[4]arene derivatives are in a cone conformation according to the ¹H NMR doublet–doublet pattern of the protons of the methylene groups between the phenol rings. The results of NMR and specific rotations indicate that the molecules have C₂ symmetry with asymmetric features.     

Azocalix[4]pyrroles: one-pot microwave and one drop water assisted synthesis, spectroscopic characterization and preliminary investigation of its complexation with copper (II)

Modified and advanced approach has been developed for the synthesis of meso-tetra(methyl) meso-tetra(4-hydroxy phenyl) calix[4]pyrrole, meso-tetra(methyl) meso-tetra(3, 5-dihydroxy phenyl) calix[4]pyrrole and their azo dyes using microwave irradiation. Results obtained from conventional method and microwave assisted synthesis have been compared in terms of ease, yield and time. Detailed reaction mechanism has also been discussed. The structures of all compounds were characterized based on FT-IR, ¹H NMR and elemental analysis. A preliminary study on efficiency of these novel azocalix[4]pyrrole receptors towards copper (II) have been carried out by UV/Vis spectrophotometry at 25 °C which shows a distinct color change from yellow to red upon complexation.     

A new and green approach for regiospecific synthesis of novel chromeno-triazolopyrimidin using tungstic acid immobilized MCM-41 as a reusable catalyst

A novel, eco-friendly and fast route has been developed for the synthesis of new and known triazolo[1,5-a]pyrimidin fused chromone derivatives via a one pot three-component reaction of 3-amino-1,2,4-triazoles, aromatic aldehydes and 4-hydroxycoumarin in aqueous medium at room temperature. These reactions are catalyzed by MCM-41-HWO₄ as a safe and recyclable mesoporous solid acid. It combines successfully the synergistic effect of green chemistry with nanocatalysis. The yields are high and the products were characterized by ¹H NMR, ¹³CNMR spectra and elemental analysis.     

Characterization and Comparative Studies on Conventional and Microwave Synthesis of Some Disulfides

Abstract

Some disulfide derivatives have been prepared by microwave assisted synthesis methodology from thiophthalimides(sulfenimides) and thiols in a modified microwave oven under reflux at 600 Watt in ethanol. Elucidation of the structures of the synthesized compounds has been performed by IR, ¹H NMR, and ¹³C NMR spectroscopic methods.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures]     

Synthesis of bis(1,5-disubstituted tetrazoles) via double four component Azido-Ugi reaction

A double four component Azido-Ugi reaction of isocyanide, TMSN₃, aldehyde, and 4,4′-sulfonyldianiline with two amine functional groups in MeOH at 65°C has been described. The synthesis of pharmacologically and structurally interesting compounds with two 1,5-disubstituted tetrazole rings via a reaction from available and inexpensive reagents under a convenient process and mild reaction conditions has been reported. Modifications in the structure of the reaction product could be followed by varying the aldehyde or isocyanide component. The products are new and were well described by Mass, ¹H NMR, and ¹³C NMR spectral studies.     

Diastereoselective synthesis of novel 3-aryloxy/alkoxy-4-benzothiazolylpyrazolyl-β-lactams: Potential synthons for novel aminoacids/nanocopolymers

A fast, efficient, and diastereoselective synthesis of novel 3-oxo-4-benzothiazolylpyrazolyl-β-lactams is described. The reaction between 2-aryloxy/alkoxyacetic acid and novel benzothiazolylpyrazole-substituted imines afforded exclusive formation of trans-β-lactams. The scope of the reaction was investigated by varying different groups on substrates (R¹, R², R³, Z). All the novel compounds were characterized using various spectroscopic techniques such as FT-IR, ¹H NMR, ¹³C NMR, elemental analysis, and mass spectrometry in representative cases. No report has been listed in the literature for the synthesis of these types of β-lactam heterocycles so far.     

Stibatriptycene

Stibatriptycene (1c) has been synthesized by cyclization of 9-(o-chlorophenyl)-9,10-dihydro-9-stibaanthracene (2c) with an excess of lithium piperidide. The general applicability of this ring closure reaction, first developed for the synthesis of phosphatriptycene (1a) and presumed to proceed by nucleophilic attack of a carbanionic centre on a (slowly generated) benzyne, has further been demonstrated by a new synthesis of the known arsatriptycene (1b) and by the synthesis of stibatriptycene (1c). The structure of 1c was confirmed by IR, ¹H NMR and, in particular, by ¹³C NMR spectroscopy.     

A convenient and efficient one-pot method for the synthesis of novel acridine-calix[4]arene derivatives as new DNA binding agents via multicomponent reaction

A new approach is applied for the synthesis of novel acridine-calix[4]arene derivatives via a multicomponent reaction. These compounds have been characterised by ¹H NMR, ¹³C NMR and HR-MS. Our binding studies between acridine-functionalised calix[4]arenes and calf thymus DNA (CT-DNA) via fluorescence titration show that these compounds have a good affinity to CT-DNA.     

An Experimental and Theoretical Study on Influence of H‐bonding on the Synthesized Azo Derivatives Structures

We have reported a simple and efficient reaction for the synthesis of some new functionalized azo structures which were prepared by electron deficient acetylenic compounds in the presence of triphenylphosphine. The characterization of the synthesized azo compounds has been determined by FTIR, UV‐Vis, ¹H NMR, ¹³C NMR and Mass spectroscopic techniques. The influence of H‐bonding on the products has been shown by different experimental analysis. Also, the regioselectivity of the reaction, tautomerization equilibrium and the stability of products was investigated using DFT calculations at the B3LYP/6‐31G level of theory.