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Synthesis and Conformational Studies of Some Metacyclophane Compounds

International Journal of Organic Chemistry 2012年第2期2卷 152-158页

作者： Louis Korbla Doamekpor Vincent Kodzo Nartey Raphael Kwaku Klake Takehiko Yamato Department of Chemistry University of Ghana Accra Ghana epartment of Chemistry Saga University Saga Japan

Various [3.3.3]metacyclophane derivatives were synthesized from 6,15,24-tri-tert-butyl-9,18,27-trimethoxy [3.3.3] metacyclophane-2,11,20-trione 1 using simple chemical reactions. The conformations of the synthesized compounds were studied using mainly solution Proton Nuclear Magnetic Resonance (1H NMR) spectroscopic methods. Two of the synthesized compounds 5, 6, were found to have a partial cone conformation with the third, 4, having the cone conformation. Detailed variable temperature Proton Nuclear Magnetic Resonance studies further confirmed the partialcone conformation for the two products, 5, 6. During the variable temperature nuclear magnetic resonance spectroscopic studies, 6,15,24-tri-tert-butyl-9,18,27-trimethoxy[3.3.3]metacyclophane-2,11,20-triol was found to have a coalescence temperature of about 0?C.

关键词： Metacyclophanes Calixarenes Cone Partial-Cone conformers Variable Temperature Proton Nuclear Magnetic Resonance Spectroscopy Coalescence Temperature

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DFT Cancer Energy Barrier and Spectral Studies of Aspirin, Paracetamol and Some Analogues

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Computational Chemistry 2014年第1期2卷 6-17页

作者： Anwar El-Shahawy Chemistry Department Faculty of Science Assiut University Assiut Egypt.

Comparative DFT computations were studied between Paracetamol (PA) and its analogues such as p-nitroace- tanilide (PA-NO2), p-bromoacetanilide (PA-Br) and N-acetylanthranilic acid (NAA) which can be considered also as analogue of Aspirin (ASP). As well, Thio-Aspirin, Acetyl-Thio-Salicylic acid, (TASP) is another analogue of ASP. From DFT studies, it has been concluded that PA and its analogues have the predominant trans-conformers with respect to directions of the carbonyl group in the acetyl moiety and the amino-hydrogen atom but the predominant conformer of NAA molecule is the cis-form. Phenacetin (PH) molecule which has ethoxy group in the Para-position instead of the hydroxyl group in the Para-position in PA molecule is another analogue of PA. The electron transfer energy between the drugs and the nucleic acid bases can be illustrated as cancer energy barrier. The cancer energy barriers were calculated from the DFT parameters for all the studied molecules showing the carcinogenic effect. The metabolized product N-acetylimidoquinone, m-PA, is produced in the liver from PA and PH. m-PA has higher electron affinity more than those of the nucleic acid bases indicating to the strong electronic withdrawing power from the nucleus in the human being liver cell, hence m-PA is responsible for the carcinogenic behavior of the liver cell since it has low energy barrier with guanine, 0.3 eV. Therefore the electron transfer between m-PA and guanine takes place spontaneously in the liver. From CI calculations it has been concluded that the singlet transition energies for the trans and cis conformers of PA are the same. The comparative spectral studies have been scanned for some analogues in the visible and UV regions using solvents of different polarities. The complex between PA and Zn2+ was studied by DFT method.

关键词： B3LYP CI Paracetamol Aspirin Electron Transfer conformers UV Spectra

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