Conformational analysis of 9alpha-acetoxycumambrine A 1 and 8-O-isobutiryl-9alpha-acetoxycumambrine B 2 was carried out by low-temperature NMR studies. Results suggested that lactones 1 and 2 are mixtures of two distinctive conformers, I and II. Based on low-temperature H-1 NMR spectra, in four solvents, the thermodynamic parameters of I reversible arrow II exchange process were assessed. Energy of activation of I -- gt II reaction was obtained by dynamic NMR simulations for both compounds. Results revealed that conformational exchange of lactones 1 and 2 occurs due to "chair reversible arrow twisted chair" interconversion of a heptane ring. The same PM3 semiempirical method was applied for geometry optimization of lactones 1 and 2, as well as of 9alpha-hydroxycumambrine A 3, 9alpha-acetoxycumambrine B 4, and cumambrine B 5.
TY - JOUR
AU - Milosavljevic, S
AU - Juranić, Ivan O.
AU - Bulatović, V.
AU - Macura, S.
AU - Juranić, N.
AU - Limbach, HH
AU - Weisz, K
AU - Vajs, Vlatka
AU - Todorović, Nevena M.
PY - 2004
UR - https://cherry.chem.bg.ac.rs/handle/123456789/581
AB - Conformational analysis of 9alpha-acetoxycumambrine A 1 and 8-O-isobutiryl-9alpha-acetoxycumambrine B 2 was carried out by low-temperature NMR studies. Results suggested that lactones 1 and 2 are mixtures of two distinctive conformers, I and II. Based on low-temperature H-1 NMR spectra, in four solvents, the thermodynamic parameters of I reversible arrow II exchange process were assessed. Energy of activation of I -- gt II reaction was obtained by dynamic NMR simulations for both compounds. Results revealed that conformational exchange of lactones 1 and 2 occurs due to "chair reversible arrow twisted chair" interconversion of a heptane ring. The same PM3 semiempirical method was applied for geometry optimization of lactones 1 and 2, as well as of 9alpha-hydroxycumambrine A 3, 9alpha-acetoxycumambrine B 4, and cumambrine B 5.
PB - Kluwer Academic/Plenum Publ, New York
T2 - Structural Chemistry
T1 - Conformational analysis of guaianolide-type sesquiterpene lactones by low-temperature NMR spectroscopy and semiempirical calculations
VL - 15
IS - 3
SP - 237
EP - 245
DO - 10.1023/B:STUC.0000021533.65546.57
UR - Kon_1580
ER -
@article{
author = "Milosavljevic, S and Juranić, Ivan O. and Bulatović, V. and Macura, S. and Juranić, N. and Limbach, HH and Weisz, K and Vajs, Vlatka and Todorović, Nevena M.",
year = "2004",
abstract = "Conformational analysis of 9alpha-acetoxycumambrine A 1 and 8-O-isobutiryl-9alpha-acetoxycumambrine B 2 was carried out by low-temperature NMR studies. Results suggested that lactones 1 and 2 are mixtures of two distinctive conformers, I and II. Based on low-temperature H-1 NMR spectra, in four solvents, the thermodynamic parameters of I reversible arrow II exchange process were assessed. Energy of activation of I -- gt II reaction was obtained by dynamic NMR simulations for both compounds. Results revealed that conformational exchange of lactones 1 and 2 occurs due to "chair reversible arrow twisted chair" interconversion of a heptane ring. The same PM3 semiempirical method was applied for geometry optimization of lactones 1 and 2, as well as of 9alpha-hydroxycumambrine A 3, 9alpha-acetoxycumambrine B 4, and cumambrine B 5.",
publisher = "Kluwer Academic/Plenum Publ, New York",
journal = "Structural Chemistry",
title = "Conformational analysis of guaianolide-type sesquiterpene lactones by low-temperature NMR spectroscopy and semiempirical calculations",
volume = "15",
number = "3",
pages = "237-245",
doi = "10.1023/B:STUC.0000021533.65546.57",
url = "Kon_1580"
}
Milosavljevic, S., Juranić, I. O., Bulatović, V., Macura, S., Juranić, N., Limbach, H., Weisz, K., Vajs, V.,& Todorović, N. M.. (2004). Conformational analysis of guaianolide-type sesquiterpene lactones by low-temperature NMR spectroscopy and semiempirical calculations. in Structural Chemistry
Kluwer Academic/Plenum Publ, New York., 15(3), 237-245.
https://doi.org/10.1023/B:STUC.0000021533.65546.57
Kon_1580
Milosavljevic S, Juranić IO, Bulatović V, Macura S, Juranić N, Limbach H, Weisz K, Vajs V, Todorović NM. Conformational analysis of guaianolide-type sesquiterpene lactones by low-temperature NMR spectroscopy and semiempirical calculations. in Structural Chemistry. 2004;15(3):237-245.
doi:10.1023/B:STUC.0000021533.65546.57
Kon_1580 .
Milosavljevic, S, Juranić, Ivan O., Bulatović, V., Macura, S., Juranić, N., Limbach, HH, Weisz, K, Vajs, Vlatka, Todorović, Nevena M., "Conformational analysis of guaianolide-type sesquiterpene lactones by low-temperature NMR spectroscopy and semiempirical calculations" in Structural Chemistry, 15, no. 3 (2004):237-245,
https://doi.org/10.1023/B:STUC.0000021533.65546.57 .,
Kon_1580 .
