- The isomeric structure of pentacoordinate chiral spirophosphoranes in solution by the combined use of NMR experiments and GIAO DFT calculations of NMR parameters
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The interplay of NMR experiments and DFT calculations of NMR parameters is a reliable method for determining the relative configurations of pentacoordinate chiral spirophosphoranes bearing two six- or five-membered rings at the phosphorus atom in solution. The major product of the Betti based derivatives corresponds to the isomers with both substituents at chiral carbons being opposite to the P-H proton. The next populated product corresponds to the isomer with different chiralities at carbons. The least populated isomer is one with both substituents being at the same side of the heterocycle as the P-H bond.
- Polyancev, Fedor M.,Metlushka, Kirill E.,Sadkova, Dilyara N.,Khisametdinova, Zilya R.,Kataeva, Olga N.,Alfonsov, Vladimir A.,Latypov, Shamil K.,Sinyashin, Oleg G.
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- High-performance liquid chromatographic enantioseparation of Betti base analogs on a newly developed isopropyl carbamate-cyclofructan6-based chiral stationary phase
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The direct separation of the enantiomers of 1-(α-aminoarylmethyl)-2- naphthol, 1-(α-aminoalkyl)-2-naphthol, 2-(α-aminoarylmethyl)-1- naphthol analogs, and 2-(1-amino-2-methylpropyl)-1-naphthol) was performed on a newly developed chiral stationary phase containing isopropyl carbamate-cyclofructan6 as chiral selector, with n-heptane/alcohol/ trifluoroacetic acid as mobile phase. The effects of the mobile-phase composition, the nature and concentration of the alcoholic and acidic modifiers, and the structures of the analytes on the retention and resolution were investigated. In some cases, separations were carried out at constant mobile-phase compositions in the temperature range 5-40°C. Thermodynamic parameters and Tiso values were calculated from plots of ln k′ or ln α versus 1/T. -Δ(ΔH°) ranged from 2.8 to 3.2 kJ mol-1, -Δ(ΔS°) from 7.7 to 10.1 J mol-1 K-1, and -Δ(ΔG°) from 0.2 to 0.5 kJ mol-1. It was found that the enantioseparations were enthalpy driven. The sequence of elution of the stereoisomers determined in some cases was (R) (S).
- Aranyi, Anita,Ilisz, Istvan,Pataj, Zoltan,Szatmari, Istvan,Fueloep, Ferenc,Armstrong, Daniel W.,Peter, Antal
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experimental part
p. 549 - 556
(2012/01/05)
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- Efficient synthesis of naphtho[1,2-e][1,3]oxazine derivatives via a chemoselective reaction with the aid of low-valent titanium reagent
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A series of new naphtho[1,2-e][1,3]oxazine derivatives such as trans-1,3-diaryl-1H-naphtho[1,2-e][1,3]oxazine-2(3H)-carbonyl chloride, 1-aryl-2-benzyl-1,2- dihydronaphtho[1,2-e][1,3]oxazine-3-one, and trans-1,3-diaryl-1H-naphtho[1,2-e] [1,3]oxazine-2(3H)-
- Shi, Daqing,Rong, Shaofeng,Dou, Guolan,Wang, Manman
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scheme or table
p. 25 - 30
(2010/10/03)
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- Stereoelectronic effects in ring-chain tautomerism of 1,3-diarylnaphth[1,2-e][1,3]oxazines and 3-alkyl-1-arylnaphth[1,2-e][1,3]oxazines
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The disubstitution effects of X and Y in 1-(Y-phenyl)-3-(X-phenyl)-2,3-dihydro-1H-naphth[1,2-e][1,3]oxazines on the ring-chain tautomerism, the delocalization of the nitrogen lone pair (anomeric effect), and the 13C NMR chemical shifts were ana
- Szatmari, Istvan,Martinek, Tamas A.,Lazar, Laszlo,Koch, Andreas,Kleinpeter, Erich,Neuvonen, Kari,Fueloep, Ferenc
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p. 3645 - 3653
(2007/10/03)
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