TY - JOUR
T1 - Conformational analysis of perezone and dihydroperezone using vibrational circular dichroism
AU - Burgueño-Tapia, Eleuterio
AU - Cerda-García-Rojas, Carlos M.
AU - Joseph-Nathan, Pedro
N1 - Funding Information:
Partial financial support from Conacyt Mexico and SIP-IPN (Grant No. 20110391 ) is acknowledged. E.B.T. is fellows of COFAA and EDI of IPN.
PY - 2012/2
Y1 - 2012/2
N2 - The vibrational circular dichroism (VCD) spectra of perezone and dihydroperezone measured from CDCl 3 solutions were quite similar, suggesting analogous conformations for both molecules. Their absolute configurations were confirmed by comparison of the experimental VCD spectrum of each compound with curves generated from theoretical calculations using density functional theory (DFT) at the B3LYP/DGDZVP level of theory taking into account their conformational mobility. Conformational analysis of the 8-(R) enantiomer showed 19 low energy conformers in a 2.4 kcal/mol energy range, while for 8-(R), with the saturated side alkyl chain, 34 conformers were considered in the first 2 kcal/mol. Initial analyses were carried out using a Monte Carlo searching with the MMFF94 molecular mechanics force field, all MMFF94 conformers were geometrically optimized using DFT at the B3LYP/6-31G(d) level of theory, followed by reoptimization and calculations of their vibrational frequencies at the B3LYP/DGDZVP level. Good agreement between the theoretical 8-(R) enantiomers and experimental VCD curves were observed for both.
AB - The vibrational circular dichroism (VCD) spectra of perezone and dihydroperezone measured from CDCl 3 solutions were quite similar, suggesting analogous conformations for both molecules. Their absolute configurations were confirmed by comparison of the experimental VCD spectrum of each compound with curves generated from theoretical calculations using density functional theory (DFT) at the B3LYP/DGDZVP level of theory taking into account their conformational mobility. Conformational analysis of the 8-(R) enantiomer showed 19 low energy conformers in a 2.4 kcal/mol energy range, while for 8-(R), with the saturated side alkyl chain, 34 conformers were considered in the first 2 kcal/mol. Initial analyses were carried out using a Monte Carlo searching with the MMFF94 molecular mechanics force field, all MMFF94 conformers were geometrically optimized using DFT at the B3LYP/6-31G(d) level of theory, followed by reoptimization and calculations of their vibrational frequencies at the B3LYP/DGDZVP level. Good agreement between the theoretical 8-(R) enantiomers and experimental VCD curves were observed for both.
KW - Absolute configuration
KW - Compositae
KW - Dihydroperezone
KW - Perezia adnata var. alamani
KW - Perezone
KW - Vibrational circular dichroism
UR - http://www.scopus.com/inward/record.url?scp=84855934100&partnerID=8YFLogxK
U2 - 10.1016/j.phytochem.2011.10.005
DO - 10.1016/j.phytochem.2011.10.005
M3 - Artículo
SN - 0031-9422
VL - 74
SP - 190
EP - 195
JO - Phytochemistry
JF - Phytochemistry
ER -