TY  - JOUR
AU  - Gođevac, Dejan
AU  - Mandić, Boris
AU  - Vajs, Vlatka
AU  - Menković, N.
AU  - Macura, S.
AU  - Milosavljević, Slobodan M.
PY  - 2006
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/784
AB  - Leucanthoside A, a new allose-containing triterpenoid saponin (1), was isolated from the aerial parts of Cephalaria leucantha L. Its structure was determined by electrospray ionization mass spectrometry and NMR spectroscopy. Complete assignments of the H-1 and 1 C NMR chemical shifts were achieved by two-dimensional NMR experiments: DQF-COSY, NOESY, TOCSY, HSQC, DINE-HSQC, HMBC, C-13-H-1 2D-J-resolved spectroscopy, and 1,1-ADEQUATE. Copyright (c) 2006 John Wiley & Sons, Ltd.
PB  - John Wiley & Sons Ltd, Chichester
T2  - Magnetic Resonance in Chemistry
T1  - Complete assignments of H-1 and C-13 NMR spectra of leucanthoside A, a new triterpenoid saponin from Cephalaria leucantha L.
VL  - 44
IS  - 7
SP  - 731
EP  - 735
DO  - 10.1002/mrc.1834
ER  - 

@article{
author = "Gođevac, Dejan and Mandić, Boris and Vajs, Vlatka and Menković, N. and Macura, S. and Milosavljević, Slobodan M.",
year = "2006",
abstract = "Leucanthoside A, a new allose-containing triterpenoid saponin (1), was isolated from the aerial parts of Cephalaria leucantha L. Its structure was determined by electrospray ionization mass spectrometry and NMR spectroscopy. Complete assignments of the H-1 and 1 C NMR chemical shifts were achieved by two-dimensional NMR experiments: DQF-COSY, NOESY, TOCSY, HSQC, DINE-HSQC, HMBC, C-13-H-1 2D-J-resolved spectroscopy, and 1,1-ADEQUATE. Copyright (c) 2006 John Wiley & Sons, Ltd.",
publisher = "John Wiley & Sons Ltd, Chichester",
journal = "Magnetic Resonance in Chemistry",
title = "Complete assignments of H-1 and C-13 NMR spectra of leucanthoside A, a new triterpenoid saponin from Cephalaria leucantha L.",
volume = "44",
number = "7",
pages = "731-735",
doi = "10.1002/mrc.1834"
}

Gođevac, D., Mandić, B., Vajs, V., Menković, N., Macura, S.,& Milosavljević, S. M.. (2006). Complete assignments of H-1 and C-13 NMR spectra of leucanthoside A, a new triterpenoid saponin from Cephalaria leucantha L.. in Magnetic Resonance in Chemistry
John Wiley & Sons Ltd, Chichester., 44(7), 731-735.
https://doi.org/10.1002/mrc.1834

Gođevac D, Mandić B, Vajs V, Menković N, Macura S, Milosavljević SM. Complete assignments of H-1 and C-13 NMR spectra of leucanthoside A, a new triterpenoid saponin from Cephalaria leucantha L.. in Magnetic Resonance in Chemistry. 2006;44(7):731-735.
doi:10.1002/mrc.1834 .

Gođevac, Dejan, Mandić, Boris, Vajs, Vlatka, Menković, N., Macura, S., Milosavljević, Slobodan M., "Complete assignments of H-1 and C-13 NMR spectra of leucanthoside A, a new triterpenoid saponin from Cephalaria leucantha L." in Magnetic Resonance in Chemistry, 44, no. 7 (2006):731-735,
https://doi.org/10.1002/mrc.1834 . .

TY  - JOUR
AU  - Marković, R.
AU  - Baranac-Stojanović, Marija
AU  - Juranić, N.
AU  - Macura, S.
AU  - Cekic, I.
AU  - Minić, Dragica M.
PY  - 2006
UR  - https://cherry.chem.bg.ac.rs/handle/123456789/813
AB  - The rotational barriers between the configurational isomers of two structurally related push-pull 4-oxothiazolidines, differing in the number of exocyclic C=C bonds, have been determined by dynamic H-1 NMR spectroscopy. The equilibrium mixture of (5-ethoxy-carbonylmethyl-4-oxothiazolidin-2-ylidene)-1-phenylethanone (1a) in CDCl3 at room temperature to 333 K consists of the E- and Z-isomers which are separated by an energy barrier Delta G(#) 98.5 kJ/mol (at 298 K). The variable-temperature H-1 NMR data for the isomerization of ethyl (5-ethoxycarbonylmethylidene-4-oxothiazolidin-2-ylidene)ethanoate (2b) in DMSO-d(6), possessing the two exocyclic C=C bonds at the C(2)- and C(5)-positions, indicate that the rotational barrier Delta G(#) separating the (2E,5Z)-2b and (2Z,5Z)-2b isomers is 100.2 kJ/mol (at 298 K). In a polar solvent-dependent equilibrium the major (2Z,5Z)-form ( gt  90%) is stabilized by the intermolecular resonance-assisted hydrogen bonding and strong 1,5-type (SO)-O-... interactions within the S-C=C-C=O entity. The C-13 NMR Delta delta(C(2)C(2')) values, ranging from 58 to 69 ppm in 1a-d and 49-58 ppm in 2a-d, correlate with the degree of the push-pull character of the exocyclic C(2)=C(2') bond, which increases with the electron withdrawing ability of the substituents at the vinylic C(2') position in the following order: COPh similar to COEt  gt  CONHPh  gt  CONHCH2CH2Ph. The decrease of the Delta delta(C(2)C(2')) values in 2a-d has been discussed for the first time in terms of an estimation of the electron donor capacity of the -S- fragment on the polarization of the C=C bonds. (c) 2006 Elsevier B.V. All rights reserved.
PB  - Elsevier Science Bv, Amsterdam
T2  - Journal of Molecular Structure
T1  - H-1 NMR dynamic study of thermal Z/E isomerization of 5-substituted 2-alkylidene-4-oxothiazolidine derivatives: Barriers to rotation about C=C bond
VL  - 800
IS  - 1-3
SP  - 85
EP  - 92
DO  - 10.1016/j.molstruc.2006.03.075
ER  - 

@article{
author = "Marković, R. and Baranac-Stojanović, Marija and Juranić, N. and Macura, S. and Cekic, I. and Minić, Dragica M.",
year = "2006",
abstract = "The rotational barriers between the configurational isomers of two structurally related push-pull 4-oxothiazolidines, differing in the number of exocyclic C=C bonds, have been determined by dynamic H-1 NMR spectroscopy. The equilibrium mixture of (5-ethoxy-carbonylmethyl-4-oxothiazolidin-2-ylidene)-1-phenylethanone (1a) in CDCl3 at room temperature to 333 K consists of the E- and Z-isomers which are separated by an energy barrier Delta G(#) 98.5 kJ/mol (at 298 K). The variable-temperature H-1 NMR data for the isomerization of ethyl (5-ethoxycarbonylmethylidene-4-oxothiazolidin-2-ylidene)ethanoate (2b) in DMSO-d(6), possessing the two exocyclic C=C bonds at the C(2)- and C(5)-positions, indicate that the rotational barrier Delta G(#) separating the (2E,5Z)-2b and (2Z,5Z)-2b isomers is 100.2 kJ/mol (at 298 K). In a polar solvent-dependent equilibrium the major (2Z,5Z)-form ( gt  90%) is stabilized by the intermolecular resonance-assisted hydrogen bonding and strong 1,5-type (SO)-O-... interactions within the S-C=C-C=O entity. The C-13 NMR Delta delta(C(2)C(2')) values, ranging from 58 to 69 ppm in 1a-d and 49-58 ppm in 2a-d, correlate with the degree of the push-pull character of the exocyclic C(2)=C(2') bond, which increases with the electron withdrawing ability of the substituents at the vinylic C(2') position in the following order: COPh similar to COEt  gt  CONHPh  gt  CONHCH2CH2Ph. The decrease of the Delta delta(C(2)C(2')) values in 2a-d has been discussed for the first time in terms of an estimation of the electron donor capacity of the -S- fragment on the polarization of the C=C bonds. (c) 2006 Elsevier B.V. All rights reserved.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "Journal of Molecular Structure",
title = "H-1 NMR dynamic study of thermal Z/E isomerization of 5-substituted 2-alkylidene-4-oxothiazolidine derivatives: Barriers to rotation about C=C bond",
volume = "800",
number = "1-3",
pages = "85-92",
doi = "10.1016/j.molstruc.2006.03.075"
}

Marković, R., Baranac-Stojanović, M., Juranić, N., Macura, S., Cekic, I.,& Minić, D. M.. (2006). H-1 NMR dynamic study of thermal Z/E isomerization of 5-substituted 2-alkylidene-4-oxothiazolidine derivatives: Barriers to rotation about C=C bond. in Journal of Molecular Structure
Elsevier Science Bv, Amsterdam., 800(1-3), 85-92.
https://doi.org/10.1016/j.molstruc.2006.03.075

Marković R, Baranac-Stojanović M, Juranić N, Macura S, Cekic I, Minić DM. H-1 NMR dynamic study of thermal Z/E isomerization of 5-substituted 2-alkylidene-4-oxothiazolidine derivatives: Barriers to rotation about C=C bond. in Journal of Molecular Structure. 2006;800(1-3):85-92.
doi:10.1016/j.molstruc.2006.03.075 .

Marković, R., Baranac-Stojanović, Marija, Juranić, N., Macura, S., Cekic, I., Minić, Dragica M., "H-1 NMR dynamic study of thermal Z/E isomerization of 5-substituted 2-alkylidene-4-oxothiazolidine derivatives: Barriers to rotation about C=C bond" in Journal of Molecular Structure, 800, no. 1-3 (2006):85-92,
https://doi.org/10.1016/j.molstruc.2006.03.075 . .