Salim S. Sabri, Must, " Synthesis and spectral properties of some N-(2-Benzimidazoyl) -aminoesters and their N-oxides " , "J.Heterocyclic Chemistry.,.",Vol.24,No.1, Wiley-Blackwell, USA, 01/13/1987
:الملخص
A series of new N-(2-benzimidazol)(S)-α-aminoesters and the respective N-oxides have been prepared, and their spectral data discussed. The CD spectra of the aliphatic and aromatic amino ester derivatives of either series show sign reversal for the observed Cotton effect (CE) band. This chiroptical behaviour was rationalized as due to differences in conformational isomerism.
Hani A. Y. Mohammad,, " C-H oxidative Addition with a (PCP) IrIII –Pincer Complex, " , "Organometallics",Vol.21,No.26, Copyright © 2002 American Chemical Society, USA, 11/27/2002
:الملخص
Treatment of 4-MeO-C6H3-2,6-(CH2PtBu2)2 with IrCl3·nH2O in i-PrOH/H2O gives a cyclometalated pincer chlorohydrido iridium complex. A second intramolecular oxidative addition reaction of one of the tert-butyl C−H bonds to the Ir(III) center followed by the reductive elimination of H2 gives a novel doubly metalated compound that is stable to air and water. X-ray crystallographic analysis revealed a chelated square-pyramidal iridium compound with two cyclometalated five-membered rings in the basal plane and the iridium bound methylene group of the four-membered ring in the apical position. The free coordination site is protected by an agostic C−H bond. While a phosphorus−phosphorus coupling constant of 351.1 Hz establishes the trans position of the phosphorus groups there is no indication of a hydridic or weakly bound hydrogen. Electrochemical studies establish an equilibrium between the pincer chlorohydrido compound and the doubly metalated complex and H2. A square scheme can be used to describe the relationship between the redox couples and solution equilibria. The unusual stability of the doubly metalated complex was supported by DFT calculations at different levels of theory on model compounds. They show the coordination of two hydrogen atoms best described as η2-coordinated dihydrogen and suggest an Ir(V) oxidation state as intermediate.
Mustafa M. El-Abadel, " Synthesis and properties of iso Viagra. A 2-Methyl- 2H-pyrazolo[4,3-d]pyrimidin-7-one Isomer of Viagra, " , "J.Heterocyclic Chem",Vol.39,No.5, Wiley-Blackwell, USA, 07/23/2002
:الملخص
he synthesis and spectral properties (ir, ms, nmr) of a substituted 2-methyl-2H-pyrazolo[4,3-d]-pyrimidin-7-one (3), an isomer of Viagra®, are described. The key synthon, 4-amino-1-methyl-5-propyl-3-pyrazolecarboxamide (7), is prepared via the reaction of ethyl 2,4-dioxoheptanoate with methylhydrazine, followed by cyclization, nitration, amidation, and nitro group reduction. Interaction of 7 with 2-ethoxyben-zoyl chloride yielded the respective bis-amide (8) which was cyclized in polyphosphoric acid to the corresponding pyrazolo[4,3-d]pyrimidin-7-one derivative 9. Chlorosulfonylation of 9, and subsequent treatment with 1-methylpiperazine furnished iso Viagra (3).
Filip Novak, Bernd s, " Electrochemistry of transition metal complex catalysts. Part 10. Intra- and intermolecular electrochemically activated C-H addition to the central metal atom of a P-C-P- pincer iridium complex. " , "Electrochimica Acta ",Vol.49,No.22-23, Copyright © 2014 Elsevier Ltd, Amsterdam,Holland, 09/15/2004
:الملخص
The electrochemical properties of a promising catalyst for CH bond activation are investigated. This P–C–P-pincer complex of iridium exhibits an intramolecular CH oxidative addition at room temperature, which becomes enhanced upon oxidation. The reaction product is detected by cyclic voltammetry. Mechanistic, kinetic, and thermodynamic information is extracted from experiments in combination with digital simulation. Multicycle voltammograms and voltammograms of mixtures consistently suggest an extended square scheme as the electrode reaction mechanism. The unsubstituted parent compound shows a more complex redox behavior including a coupled ECE sequence. Intermolecular CH activation by reaction of the complex in the presence of cyclooctane is indicated by characteristic changes in the cyclic voltammograms.
Bassam A. Sweileh *,, " Synthesis and Characterization of Polycarbonates by Melt Phase Interchange Reactions of Alkylene and Arylene Diacetates with Alkylene and Arylene Diphenyl Dicarbonates. " , "Molecules",Vol.15,No.05, , , 05/18/2010
:الملخص
Abstract: This work presents a new synthetic approach to aromatic and aliphatic polycarbonates by melt polycondensation of bisphenol A diacetates with alkylene- and arylenediphenyl dicarbonates. The diphenyl dicarbonates were prepared from phenyl chloroformate and the corresponding dihydroxy compounds. The process involved a precondensation step under a slow stream of dry argon with the elimination of phenyl acetate, followed by melt polycondensation at high temperature and under vacuum. The potential of this reaction is demonstrated by the successful synthesis of a series of aromatic-aromatic and aromatic-aliphatic polycarbonates having inherent viscosities from 0.19 to 0.43 dL/g. Thus low to intermediate molecular mass polymers were obtained. The 13C-NMR spectra of the carbon of the carbonate group showed that the formed polycarbonates contain partial random sequence distribution of monomer residues in their chains. The polycarbonates were characterized by inherent viscosity, FTIR, 1H-NMR and 13C-NMR spectroscopy. The glass transition temperatures, measured by DSC, of the polycarbonates were in the range 13–108 ºC. The thermogravimetric curves of showed that these polymers have good thermal stability up to 250 ºC. The present approach may open the door for novel polycarbonates containing other organic functional groups.
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B. A. Sweileh,H. R. , " Synthesis and characterization of poly(ester carbonate)s by melt-phase interchange reactions of dihydroxy compounds with alkylene and arylene diphenyl dicarbonates containing ester groups " , "J. Appl. Polym. Sci. ",Vol.131,No.5, © 2013 Wiley Periodicals, Inc, , 03/05/2014
:الملخص
A new method of synthesis of poly(ester carbonate)s, based on the reaction of dihydroxy compounds with diphenyl dicarbonates containing ester groups was presented. The monomers utilized were diphenyl dicarbonates of cis/trans-1,4-cyclohexane dicarboxylate and of terephthalate units with butanediol or bisphenol A. The process consisted of a precondensation step under a stream of dry argon at atmospheric pressure with the elimination of phenol, followed by a melt polycondensation step at 225 or 250°C under vacuum. The prepared polymers consisted of linear chains containing partial random sequence distribution of monomer residues in the backbone. The inherent viscosities of polymers were from 0.23 to 0.48 dL/g and their Tg values were in the range −9 to 134°C. This method may open door to novel polycarbonates containing other organic functional groups
Kamal Sweidan*, Wali, " Synthesis and Antibacterial Evaluation of Model Fluoroquinolone-Benzylidene Barbiturate Hybrids " , "Letters in Organic Chemistry",Vol.11,No.10, , Spain, 11/26/2014
