Search results for "Pyrrole"
showing 10 items of 311 documents
ChemInform Abstract: Polycondensed Nitrogen Heterocycles. Part 23. Pyrrolo(3,2-c)cinnolines by a Japp-Klingemann-Type Reaction.
1990
Pyrrolo[3,2-c]cinnoline derivatives were obtained by an unusual Japp-Klingemann reaction involving an intramolecular azadehalogenation on the pyrrole nucleus. Such an azadehalogenation represents the first example of Japp-Klingemann reaction in which the extrusion of positive chlorine ion is verified.
ChemInform Abstract: Total Synthesis of (-)-Hymenosetin.
2016
Hymenosetin (I) and its N-methyl analogue are prepared in 11 and 8 steps, respectively, from citronellal employing an intramolecular Diels-Alder reaction as the key step.
ChemInform Abstract: Modular One-Pot Synthesis of Tetrasubstituted Pyrroles from α-(Alkylideneamino)nitriles.
2008
2,3,4,5-Tetrasubstituted pyrroles have been prepared with high regioselectivity by a formal cycloaddition of α-(alkylideneamino)nitriles and nitroolefins followed by elimination of HCN and HNO2. The reaction allows the convergent construction of the pyrrole ring in four steps from a nitroalkane and three aldehydes.
Mechanochemical Syntheses of N-Containing Heterocycles with TosMIC
2021
A mechanochemical van Leusen pyrrole synthesis with a base leads to 3,4-disubstitued pyrroles in moderate to excellent yields. The developed protocol is compatible with a range of electron-withdrawing groups and can also be applied to the synthesis of oxazoles. Attempts to mechanochemically convert the resulting pyrroles into porphyrins proved to be difficult.
Mechanism of redox transformation of titanocene dichloride centers immobilized inside a polypyrrole matrix—EQCM and XPS evidences
2005
Abstract We report electrochemical quartz crystal microbalance (EQCM) results for electrodeposition of titanocene derivatized polypyrrole p(Tc3Py) films and redox transformation of polypyrrole matrix and titanocene centers immobilized in the film. Films of p(Tc3Py), Tc3Py = Tc(CH 2 ) 3 NC 4 H 4 (Tc = Cl 2 TiCpCp′, Cp = C 5 H 5 , Cp′ = C 5 H 4 ) were obtained from acetonitrile solutions of monomer on a Pt disc or thin Au layer evaporated on 10 MHz quartz crystals. Polymerization efficiency, derived from the slope of the change of resonant frequency as a function of the deposition charge ranged from 54% to 75%. A gradual loss of redox activity of Tc centers during consecutive redox cycles of …
ChemInform Abstract: Facile Synthesis of Pyrazoles and Pyrroles via Thermolysis of Tetrazolo[1,5-b]pyridazines, Tetrazolo[1,5-a]pyrimidines and Tetra…
2010
Abstract A simple and high yielding preparation of pyrazoles and pyrroles is described. Thermolysis of tetrazolo[1,5- b ]pyridazines, tetrazolo[1,5- a ]pyrimidines and tetrazolo[1,5- a ]pyridines allowed easy ring contraction thus providing a facile preparation of cyanopyrazole and cyanopyrrole heterocycles. Since the cyano group is a versatile precursor of other functionalities, the reaction appears of particular interest for the construction of a variety of pyrazoles and pyrroles. The simple preparation of the starting tetrazole derivatives, the relatively mild conditions employed, and the very short reaction times make this versatile procedure of great synthetic utility and applicable bo…
Palladium–Polypyrrole Nanoparticles-Catalyzed Sonogashira Coupling
2012
Abstract Palladium nanoparticles were encapsulated into polypyrrole globules via one-step one-pot redox reaction between tetraamminepal- ladium(ii) dichloride and pyrrole in water. Such a material is an active catalyst for the Sonogashira coupling of iodo- and bromo- arenes.
Removal of Chromophore-proximal Polar Atoms Decreases Water Content and Increases Fluorescence in a Near Infrared Phytofluor
2015
Genetically encoded fluorescent markers have revolutionized cell and molecular biology due to their biological compatibility, controllable spatiotemporal expression, and photostability. To achieve in vivo imaging in whole animals, longer excitation wavelength probes are needed due to the superior ability of near infrared light to penetrate tissues unimpeded by absorbance from biomolecules or autofluorescence of water. Derived from near infrared-absorbing bacteriophytochromes, phytofluors are engineered to fluoresce in this region of the electromagnetic spectrum, although high quantum yield remains an elusive goal. An invariant aspartate residue is of utmost importance for photoconversion in…
Crystal structure of diaqua[5,10,15,20-tetrakis(4-methoxyphenyl)porphyrinato-κ4N]iron(III) diaqua(18-crown-6)potassium bis(trifluoromethanesulfonate)…
2015
In the title compound, [FeIII(C48H36N4O2)(H2O)2][K(C12H24O6)(H2O)2](SO3CF3)2·2C12H24O6, the FeIIIatom is situated on an inversion centre and is octahedrally coordinated by four pyrrole N atoms of the deprotenated 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrinate ligand and two water molecules. The average equatorial Fe—N(pyrrole) bond length [2.043 (6) Å] is consistent with a high-spin (S= 5/2) iron(III) metalloporphyrin derivative. The K+cation, which also lies on an inversion centre, is chelated by the six O atoms of one 18-crown-6 molecule and is additionally coordinated by two water molecules in a distorted hexagonal–bipyramidal geometry. In the crystal, the cations, anions and one non-c…
1-(1-Benzyl-2,5-dimethyl-4-phenyl-1H-pyrrol-3-yl)ethanone
2017
In the title compound, C21H21NO, the dihedral angles between the planes of the phenyl and pyrrole rings are 47.04 (5) and 79.27 (3)°. In the crystal, centrosymmetrically related molecules are linked into dimers by pairs of C—H...O hydrogen bonds, forming rings of graph-set motifR22(16).