Self-sorting under solvent-free conditions: one-pot synthesis of a hetero[3]rotaxane

The one-pot synthesis of a hetero[3]rotaxane, assembled from five different molecular components under solvent-free conditions, through "self-sorting" of the bead and stopper units during the threading and stoppering processes, is reported.     

Sulfated polyborate catalyzed expeditious and efficient three-component synthesis of 3-methyl-4-(hetero)arylmethylene isoxazole-5(4H)-ones

A rapid and highly efficient methodology for the synthesis of 3-methyl-4-(hetero)arylmethylene isoxazole-5(4H)-ones has been developed using sulfated polyborate as a catalyst. The multicomponent reaction of an aromatic/heterocyclic aldehyde, hydroxylamine hydrochloride, and ethyl acetoacetate under a solvent free condition at 80 °C is described. This protocol has promising features for the reaction response such as shorter reaction time, easy work-up, ease of separation of pure product with high yields and simplicity in the experimental procedure. The products have been obtained in high yields (80–90%) and convenient reaction time (15–30 min). The method is operationally simple and eco-friendly.     

Caffeine-H3PO4: a novel acidic catalyst for various one-pot multicomponent reactions

Research on Chemical Intermediates - Caffeine-H3PO4 along with caffeine-HClO4 and caffeine-HNO3 have been prepared and applied for one-pot preparation of bis(indolyl) methanes,...     

Design and characterization of [(Et)3 N-H]FeCl4 as a nanomagnetic ionic liquid catalyst for the synthesis of xanthene derivatives under solvent-free conditions

The triethylamine-based nanomagnetic ionic liquid, [(Et)₃ N-H]FeCl₄, was synthesized, and its structural and chemical characteristics were detected. The thermogravimetric analysis indicated its high thermal stability with a decomposition temperature higher than 300 °C. Additionally, [(Et)₃ N-H]FeCl₄ was used to efficiently catalyze the synthesis of xanthene derivatives under solvent-free conditions at 120 °C. [(Et)₃ N-H]FeCl₄ was recycled and reused at least five times.

Graphical abstract

     

Quantum-chemical investigation of the mechanism of trans-cis photoisomerization of 4-[2-(2-chlorophenyl)vinyl]-6,6-dimethyl-2-oxo-1,2,5,6-tetrahydropyridine-3-carbonitrile

A quantum-chemical investigation has been carried out by the semiempirical AM1 method of the trans-cis photoisomerization mechanism of 4-[2-(2-chlorophenyl)vinyl]-6,6-dimethyl-2-oxo-1,2,5,6-tetra- hydropyridine-3-carbonitrile. It was shown that the isomerization process proceeds in the excited singlet state S₁ by rotation of the 2-chlorophenyl substituent around the C(2)–C(3) bond. Electronic absorption spectra of the isomers were calculated by the INDO/S method Transitions caused by exitation of an electron from HOMO to LUMO were characterized by the greatest intensity.     

Synthesis of alkyl 4-(diethoxymethyl)-3-pyridin-3-ylisoxazole-5-carboxylates: useful scaffold for highly functionalised 3-(pyridin-3-yl)isoxazoles

The methyl 4-(diethoxymethyl)-3-(pyridin-3-yl)isoxazole-5-carboxylate obtained by domino 1,3-dipolar cycloaddition and elimination starting of pyridine-3-nitrile oxide and methyl 4,4-diethoxy-3-p-tolylsulfinylbut-2-enoate is a convenient scaffold for the synthesis of other new highly functionalised 3-pyridin-3-ylisoxazoles-5-carboxylic acid derivatives and isoxazole-annulated heterocycles.     

The first synthesis of 3-nitro-4-[(s-tetrazin-3-yl)amino]furazans

Oxidation of 3-amino-4-[(s-tetrazin-3-yl)amino]furazans with peroxy acids or 30% H2O2/Na2WO4/H2SO4 system results in transformation of the amino group into the nitro one and is accompanied by formation of N-oxides at tetrazine moiety.     

A one-pot synthesis to [(Me3Si)3SiSb]4; a potential precursor for Sb42-

The reaction of (Me(3)Si)(3)SiK[middle dot]18-crown-6 with SbCl(3)(3 : 1 equiv.) provides a simple route to the title complex [(Me(3)Si)(3)SiSb](4). The potassium base initially acts as a nucleophile and then as a coupling agent, forming Sb-Sb bonds.     

无溶剂条件下勃姆石纳米粒子锅催化多组分合成3,4-二氢嘧啶-2-(1H)酮简

A simple, green, and efficient synthesis protocol for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones using boehmite nanoparticles as catalyst was developed. It did not use any toxic metal catalysts or corrosive acidic reagents. The method gave good to excellent yields and has short reaction time, operational simplicity, and a recyclable catalyst.     

Development of 5-[(3-aminopropyl)phosphinooxy]-2-(hydroxymethyl)-4H-pyran-4-one as a novel whitening agent

A stable derivative of kojic acid, 5-[(3-aminopropyl)phosphinooxy]-2-(hydroxymethyl)-4H-pyran-4-one (Kojyl-APPA), was synthesized in good yield. The effects of Kojyl-APPA on tyrosinase activity and melanin synthesis were investigated. Kojyl-APPA showed tyrosinase inhibition effect (30%) in situ, but not in vitro. Kojyl-APPA inhibited tyrosinase activity significantly at 24 h after treatment in normal human melanocytes. It means that Kojyl-APPA is not a direct inhibitor of tyrosinase itself, but it is converted to a potential inhibitor kojic acid enzymatically in cells. In addition, Kojyl-APPA decreased melanin content to 75% of control in melanoma cells and decreased neomelanin synthesis to 43% of control in normal human melanocytes. Its permeation through skin increased by about 8 times as compared with kojic acid.     

Reaction of N-[(α-acetoxy)-4-pyridylmethyl]-3,5-dimethylbenzamide with alkyl isocyanates

Reaction of N-(α-acetoxy)4-pyridylmethyl]-3,5-dimethylbenzamide 3 with methyl and ethyl isocyanates afforded 1,3-dimethyl and 1,3-diethyl-4-(3,5-dimethylbenzoylamino)-2-oxoimidazolidine-5-spiro-4′-[1′,4′-dihydro-1′-acetyl]pyridine 6a,b , respectively. However, the reaction of 3 with isopropyl, t-butyl and phenyl isocyanates gave the corresponding N,N′-diurea and the dimerization compound 8 . The structure of 6a was confirmed by crystal X-ray diffraction analysis.     

[Me4N]2[(WOS3Ag)2]: a novel quasi-one-dimensional compound

Orange–yellow plate-like crystals of a new polymeric complex [Me₄N]₂[(WOS₃Ag)₂] were obtained at room temperature from the reaction of a suspension of [Me₄N]₂[WOS₃] in MeCN with solid AgCN. The new compound is obviously formed by cyanide elimination of primary [WOS₃(AgCN)]²⁻. It is monoclinic space group P2₁/c with unit cell parameters a=20.44(2) Å, b=9.655(6) Å, c=11.913(5) Å, β=99.06(2)°, Z=4. The crystal structure was determined from single crystal diffractometer data (Mo-Kα radiation) and refined to R=0.070 (2979 reflections, 199 variables). The structure is characterized by infinite anionic chains, ${}_{\mathrm{\infty }}{}^{\mathrm{<mspace\; xmlns="true"\; sp="0.3"\; width="2px"\; linebreak="nobreak"\; is="true"></mspace><mtext>1</mtext>}}$[(WOS₃Ag)₂]²⁻. The infrared spectrum of the complex (KBr powder) shows the terminal ν(WO) as strong absorption bands found at 913 and 905 cm⁻¹. The bridging ν(WS) shows bands at 438 (vs) and 434 (sh) cm⁻¹. The anionic mass spectrum shows a peak at m/z 404 for [WOS₃Ag]⁻. In addition, the primary formation of the potential monomeric precursor [WOS₃(AgCN)]²⁻ could be established in the filtrate by mass spectroscopy.     

Synthesis of novel 1-[(2,6-dichloro-4-trifluoromethyl)phenyl]-3-aryl-1H-pyrazole-4-carbaldehydes

A series of novel 1-[(2,6-dichloro-4-trifluoromethyl)phenyl]-3-aryl-1H-pyrazole-4-carbaldehydes were synthesized using the Vilsmeier-Haack reagent. The structures of all the title compounds have been confirmed by elemental analysis, 1H-NMR and 13C-NMR and in addition, the structure of intermediate 5b was investigated by X-ray crystallography.     

4-(Succinimido)-1-butane sulfonic acid as a Bronsted acid catalyst for synthesis of pyrano[4,3-b]pyran derivatives under solvent-free conditions

4-(Succinimido)-1-butane sulfonic acid as an efficient and reusable Bronsted acid catalyzed the synthesis of pyrano[4,3-b]pyran derivatives under solvent-free conditions.The catalyst can be prepared by mixing succinimide and 1,4-butanesultone that is more simple and safer than the preparation of succinimide sulfonic acid.This method has the advantages of high yield,clean reaction,simple methodology and short reaction time.The catalyst could be recycled without significant loss of activity.     

A simple and clean method for multicomponent synthesis of spiro [indole-tetrahydropyrano(2,3-d)pyrimidine] derivatives using SBA-Pr-SO3H as catalyst under solvent-free conditions

Sulfonic acid functionalized SBA-15 (SBA-Pr-SO₃H) as a new nanoporous solid acid catalyst was applied in the green one-pot synthesis of spiro[indole-tetrahydropyrano(2,3-d)pyrimidine] derivatives via three-component reaction of isatins, malononitrile or cyanoacetic esters and barbituric acids under solvent-free conditions. SBA-Pr-SO₃H was proved to be an efficient heterogeneous nanoporous solid acid catalyst with a pore size of 6 nm, which could be easily handled and removed from the reaction mixture by simple filtration and can be recovered and reused several times without any loss of activity. The advantages of this methodology are high product yields, being environmentally benign, short reaction times, and easy handling.     

4-Hydroxy-2-quinolones. 175.*Reaction of -1-allyl-3-[(arylamino)methylene]quinoline-2,4-(1H,3H)-diones with bromine

NMR spectroscopy showed that treatment of 1-allyl-3-[(arylamino)methylene]quinoline-2,4-(1H,3H)-diones with an equivalent amount of dry bromine in anhydrous acetic acid leads to the formation of 4-aryliminomethyl-2-bromomethyl-5-oxo-1,2-dihydro-5H-oxazolo[3,2-a]quinolinium bromides.     

Greener approach: Ionic liquid [Et3NH][HSO4]-catalyzed multicomponent synthesis of 4-arylidene-2-phenyl-5(4H)oxazolones under solvent-free condition

We have developed simple, greener, safer multicomponent synthesis series of 4-arylidene-2-phenyl-5(4H) oxazolones 4(a-r) catalyzed by Bronsted acid ionic liquid as triethylammonium hydrogen sulfate [Et₃NH][HSO₄] and catalytic amount of acetic anhydride and sodium acetate with excellent yields (90–99%). The protocol offers economical, environmentally benign, solvent-free conditions, and recycle–reuse of the catalyst and easily available starting as benzoyl chloride 1, amino acid 2 and a variety of aldehydes 3. The cyclization followed by condensation of benzoyl chloride, amino acid, and a variety of aldehydes catalyzed by ILs [Et₃NH][HSO₄] and catalytic amount of acetic anhydride and sodium acetate. The final products were confirmed by their characterization data such as FTIR, ¹H-NMR, ¹³C-NMR, Mass, high-resolution mass spectra and were compared with its reported method.