Semi-empirical and vibrational studies of flavone and some deuterated analogues
摘要:
The infrared solid state, Raman solid state and tetrachloride solution spectra of flavone have been obtained. Assignments of most of the vibrational data have been performed by comparison between the spectra of flavone and three isotopic species, deuterated on the A, B and C rings, respectively. The vibrational frequencies for all the investigated compounds have been calculated from the conformational analysis of flavone using the semi-empirical AM1 method and compared with experimental values. The correlation is more or less satisfactory; however, for some vibrational modes, the calculated isotopic shifts agree better with experiment than do the frequencies themselves, Specific vibrational modes which retain a benzene ring monosubstituted and ortho-distributed character have been recognized in the spectra, according to literature data, isotopic frequency shifts and graphic representation of the atomic displacements.
Silver-Catalyzed Functionalization of Esters by Carbene Transfer: The Role of Ylide Zwitterionic Intermediates
作者:Riccardo Gava、M. Ángeles Fuentes、Maria Besora、Tomás R. Belderrain、Kane Jacob、Feliu Maseras、Michel Etienne、Ana Caballero、Pedro J. Pérez
DOI:10.1002/cctc.201402241
日期:2014.8
The reaction of esters with ethyl diazoacetate catalyzed by the complex [F27–TpAg(acetone)] generates α‐(acyloxy)acetates in moderate to high yields. This is a novel transformation in the context of carbene‐transfer reactions from diazo compounds that, according to experimental and theoretical data, is suggested to occur through zwitterionic intermediates.
Mechanism of the Palladium-Catalyzed Arene C–H Acetoxylation: A Comparison of Catalysts and Ligand Effects
作者:Amanda K. Cook、Melanie S. Sanford
DOI:10.1021/jacs.5b00238
日期:2015.3.4
This article describes detailed mechanistic studies focused on elucidating the impact of pyridine ligands on the Pd-catalyzed C-H acetoxylation of benzene. Three different catalysts, Pd(OAc)2, Pd(OAc)2/pyridine (1:1), and Pd(OAc)2/pyridine (1:2), are compared using a combination of mechanistic tools, including rate and order studies, Hammett analysis, detailed characterization of catalyst resting states
COUCH, M. W.;GABRIELSEN, B. M.;MIDGLEY, J. M., J. LABELLED COMPOUNDS AND RADIOPHARM., 1983, 20, N 8, 933-949
作者:COUCH, M. W.、GABRIELSEN, B. M.、MIDGLEY, J. M.
DOI:——
日期:——
Remarkably High Reactivity of Pd(OAc)2/Pyridine Catalysts: Nondirected CH Oxygenation of Arenes
作者:Marion H. Emmert、Amanda K. Cook、Yushu J. Xie、Melanie S. Sanford
DOI:10.1002/anie.201103327
日期:2011.9.26
general applicability of the catalytic system Pd(OAc)2/pyridine is described (see scheme). The catalyst shows excellent reactivity in the CHoxygenation of simple aromatic substrates. The Pd/pyridine ratio is critical as the use of one equivalent of pyridine per Pd center leads to dramatic enhancements in both reactivity and site selectivity in comparison to Pd(OAc)2 alone.
The infrared solid state, Raman solid state and tetrachloride solution spectra of flavone have been obtained. Assignments of most of the vibrational data have been performed by comparison between the spectra of flavone and three isotopic species, deuterated on the A, B and C rings, respectively. The vibrational frequencies for all the investigated compounds have been calculated from the conformational analysis of flavone using the semi-empirical AM1 method and compared with experimental values. The correlation is more or less satisfactory; however, for some vibrational modes, the calculated isotopic shifts agree better with experiment than do the frequencies themselves, Specific vibrational modes which retain a benzene ring monosubstituted and ortho-distributed character have been recognized in the spectra, according to literature data, isotopic frequency shifts and graphic representation of the atomic displacements.