- Importance of C*-H based modes and large amplitude motion effects in vibrational circular dichroism spectra: The case of the chiral adduct of dimethyl fumarate and anthracene
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The role played by the C-H based modes (C* being the chiral carbon atom) and the large amplitude motions in the vibrational absorption (VA) and vibrational circular dichroism (VCD) spectra is investigated. The example of an adduct of dimethyl fumarate and anthracene, i.e., dimethyl-(+)-(11R,12R)-9,10- dihydro-9,10-ethanoanthracene-11,12-dicarboxylate, and two deuterated isotopomers thereof specially synthesized for this goal, are considered. By comparing the experimental and DFT calculated spectra of the undeuterated and deuterated species, we demonstrate that the C-H bending, rocking, and stretching modes in the VA and VCD spectra are clearly identified in well defined spectroscopic features. Further, significant information about the conformer distribution is gathered by analyzing the VA and VCD data of both the fingerprint and the C-H stretching regions, with particular attention paid to the band shape data. Effects related to the large amplitude motions of the two methoxy moieties have been simulated by performing linear transit (LT) calculations, which consists of varying systematically the relative positions of the two methoxy moieties and calculating VCD spectra for the partially optimized structures obtained in this way. The LT method allows one to improve the quality of calculated spectra, as compared to experimental results, especially in regard to relative intensities and bandwidths.
- Passarello, Marco,Abbate, Sergio,Longhi, Giovanna,Lepri, Susan,Ruzziconi, Renzo,Nicu, Valentin Paul
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p. 4339 - 4350
(2014/07/07)
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- Stereoselective synthesis of α-methylenecyclopentenones via a Diels-Alder/retro-Diels-Alder protocol
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A new procedure for the stereoselective synthesis of cross-conjugated dienones is reported. This method makes use of the Diels-Alder adduct of anthracene and dimethyl fumarate, a precursor to a spirocyclopent-2-enone anthracene adduct as the key intermediate. The addition of propyllithium or octyllithium to the key intermediate followed by a retro-Diels-Alder reaction furnished α-methylenecyclopentenones bearing a γ-propyl or γ-octyl side chain, respectively, in moderate yields and as single geometric isomers.
- Phutdhawong, Weerachai,Eksinitkun, Gedsirin,Pyne, Stephen G.,Willis, Anthony C.,Phutdhawong, Waya S.
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p. 9270 - 9276
(2013/10/01)
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- New dibenzobicyclo[2.2.2]octane derivatives
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The interest for the synthesis and study of the metal complexes of dibenzobicyclic derivatives can be connected with the presence of a potential biological activity in such compounds. Thus, the syntheses of a new ligand belonging to the same family and of a coordination complex with europium(III) of this ligand, are presented. The proposed structures have been confirmed by the IR and NMR spectra. The antioxidative activity of the ligand and the complex are presented.
- Stǎnescu, Michaela Dina,Rus, Adina,Giurginca, Maria,Guran, Cornelia
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p. 409 - 412
(2007/10/03)
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- Synthesis of Precursors for the Pyrolytic Formation of Pentatetraenones
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3-(9',10'-Dihydro-9',10'-ethanoanthracen-11'-ylidene)prop-2-enoyl chloride and its [12',12'-2H2] and [1-13C] isotopomers have been prepared and pyrolysed. Argon matrix infrared spectroscopy showed ν2 bands at 2207.7, 2207.0, and 2168.5 cm-1 respectively for the three pentatetraenone isotopomers. The pyrolysate of the 12'-methyl substituted precursor showed a band at 2205 cm-1 which was tentatively assigned to methylpentatetraenone. The 12'-ethenyl substituted precursor gave a pyrolysate showing ketene bands but also yielded 9,10-dihydro-9,10[1',2']-benzenoanthracene.
- Arena, Phillip,Brown, Roger F. C.,Eastwood, Frank W.,McNaughton, Don
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p. 663 - 672
(2007/10/03)
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- Microwave-Induced Organic Reaction Enhancement Chemistry. 2. Simplified Techniques
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A variety of organic reactions have been conducted efficiently in a few minutes in unsealed vessels at ambient pressure in unmodified microwave ovens by using selected organic solvents.
- Bose, Ajay K.,Manhas, Maghar S.,Ghosh, Malay,Shah, Mamta,Raju, Vegesna S.,et al.
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p. 6968 - 6970
(2007/10/02)
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- PMR Spectral Studies of Diels-Alder Adducts: Anthracene-Crotonic Acid, Anthracene-Fumaric Acid and β-Naphthol-Fumaric Acid
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A series of amides (III-XI and XVII) and esters (XII-XV) of the Diels-Alder adducts, anthracene-crotonic acid (I), anthracene-fumaric acid (II) and β-naphthol-fumaric acid (XVI) have been prepared and their PMR spectra recorded.The PMR data indicate that N,N-dimethylamide and N-methylanilide derivatives of the adducts have restricted rotation about the N-CO and C-CO bonds.A trans-stereochemistry have been assigned to H-11 and H-12 in compounds I-XV and to H-2 and H-3 in compound XVI.
- Singh, Ashok Kumar,Verma, Mamta,Verma, Shiva Mohan
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p. 631 - 634
(2007/10/02)
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