189701-21-1Relevant articles and documents
Thermal and Microwave-Assisted Synthesis of Diels-Alder Adducts of [60]Fullerene with 2,3-Pyrazinoquinodimethanes: Characterization and Electrochemical Properties
Fernandez-Paniagua, Ursula M.,Illescas, Beatriz,Martin, Nazario,Seoane, Carlos,De la Cruz, Pilar,De la Hoz, Antonio,Langa, Fernando
, p. 3705 - 3710 (1997)
[4+2] Cycloaddition reactions of six-membered heterocyclic o-quinodimethanes, generated "in situ" from pyrazine derivatives, to [60]fullerene, either under thermal or microwave irradiation are described. Other microwave assisted cycloadditions involving o-quinodimethanes derived from thiophene were also performed. A comparative study of the activation energy for the boat-to-boat conformational inversion has been carried out by dynamic NMR experiments, the ΔG? values being highly dependent on the nature of the covalently attached heterocyclic systems. Theoretical calculations predict a more planar cyclohexene ring for the five member containing cycloadducts. The cycloaddition process is controlled by the HOMO of the heterocyclic o-quinodimethanes showing a LUMO(C60)-HOMO(diene) energy differences typical for favoured cycloadditions. The redox properties of the novel organofullerenes have been determined by cyclic voltammetry in solution, showing a cathodically shifted first reduction potential values, related to [60]fullerene. Compound 15c bearing two cyano groups exhibited an opposite trend which was accounted for by the lower LUMO energy determined by semiempirical calculations.
Silica-gel-catalyzed efficient synthesis of quinoxaline derivatives under solvent-free conditions
Nandi, Ganesh Chandra,Samai, Subhasis,Kumar, Ram,Singh
experimental part, p. 417 - 425 (2011/04/15)
Quinoxaline derivatives have been prepared in good to excellent yields using silica gel as catalyst from various 1,2-diketones and 1,2-diamines under solvent-free conditions for the first time. The advantages of this method are short reaction time, reaction simplicity, convenient workup procedure, and purification of compounds by a nonchromatographic method.
Synthesis of pyrazinoporphyrazine derivatives functionalised with tetrathiafulvalene (TTF) units: X-ray crystal structures of two related TTF cyclophanes and two bis(1,3-dithiole-2-thione) intermediates
Wang, Changsheng,Bryce, Martin R.,Batsanov, Andrei S.,Howard, Judith A. K.
, p. 1679 - 1690 (2007/10/03)
The pyrazinoporphyrazine system 13 (metal-free, zinc and copper derivatives) has been synthesised by tetramerisation of 2,3-dicyanopyrazine monomer unit 10. The structure of 13a-c has been established by HNMR spectroscopy, UV/Vis spectrophotometry, MALDI-TOF mass spectrometry, cyclic voltammetry and differential pulse voltammetry. The electrochemical redox behaviour of 13a-c is strongly solvent dependent. The expected two-stage oxidation of the tetrathiafulvalene (TTF) units of 13a-c was observed in a range of solvents; in addition, oxidation and reduction of the pyrazinoporphyrazine core of the metal-free derivative 13a was detected in benzonitrile. On excitation of 13 in the Q-band region no fluorescence was observed, which is presumably the consequence of intramolecular charge transfer between the TTF moieties and the excited state of the central porphyrazine. Molecular modelling studies on 13a and 13c are reported. During the course of this work, the novel TTF macrocycles 11 and 20 were synthesised; their X-ray crystal structures reveal severely bent TTF units, the conformations of which are discussed in detail. The X-ray crystal structures of the bis(1,3-dithiole) systems 15 and 18 have also been determined.
