TY - JOUR
T1 - Absolute configuration of the ocimene monoterpenoids from Artemisia absinthium
AU - Julio, Luis F.
AU - Burgueño-Tapia, Eleuterio
AU - Díaz, Carmen E.
AU - Pérez-Hernández, Nury
AU - González-Coloma, Azucena
AU - Joseph-Nathan, Pedro
N1 - Publisher Copyright:
© 2017 Wiley Periodicals, Inc.
PY - 2017/11
Y1 - 2017/11
N2 - The absolute configuration (AC) of the naturally occurring ocimenes (−)-(3S,5Z)-2,6-dimethyl-2,3-epoxyocta-5,7-diene (1) and (−)-(3S,5Z)-2,6-dimethylocta-5,7-dien-2,3-diol (2), isolated from the essential oils of domesticated specimens of Artemisia absinthium, followed by vibrational circular dichroism (VCD) studies of 1, as well as from the acetonide 3 and the monoacetate 4, both derived from 2, since secondary alcohols are not the best functional groups to be present during VCD studies in solution due to intermolecular associations. The AC follows from comparison of experimental and calculated VCD spectra that were obtained by Density Functional Theory computation at the B3LYP/DGDZVP level of theory. Careful nuclear magnetic resonance (NMR) measurements were compared with literature values, providing for the first time systematic 1H and 13C chemical shift data. Regarding homonuclear 1H coupling constants, after performing a few irradiation experiments that showed the presence of several small long-range interactions, the complete set of coupling constants for 3, which is representative of the four studied molecules, was determined by iterations using the PERCH software. This procedure even allowed assigning the pro-R and pro-S methyl group signals of the two gem-dimethyl groups present in 3.
AB - The absolute configuration (AC) of the naturally occurring ocimenes (−)-(3S,5Z)-2,6-dimethyl-2,3-epoxyocta-5,7-diene (1) and (−)-(3S,5Z)-2,6-dimethylocta-5,7-dien-2,3-diol (2), isolated from the essential oils of domesticated specimens of Artemisia absinthium, followed by vibrational circular dichroism (VCD) studies of 1, as well as from the acetonide 3 and the monoacetate 4, both derived from 2, since secondary alcohols are not the best functional groups to be present during VCD studies in solution due to intermolecular associations. The AC follows from comparison of experimental and calculated VCD spectra that were obtained by Density Functional Theory computation at the B3LYP/DGDZVP level of theory. Careful nuclear magnetic resonance (NMR) measurements were compared with literature values, providing for the first time systematic 1H and 13C chemical shift data. Regarding homonuclear 1H coupling constants, after performing a few irradiation experiments that showed the presence of several small long-range interactions, the complete set of coupling constants for 3, which is representative of the four studied molecules, was determined by iterations using the PERCH software. This procedure even allowed assigning the pro-R and pro-S methyl group signals of the two gem-dimethyl groups present in 3.
KW - absolute configuration
KW - monoterpenes
KW - ocimenes
KW - very-high-resolution nuclear magnetic resonance
KW - vibrational circular dichroism
UR - http://www.scopus.com/inward/record.url?scp=85028342759&partnerID=8YFLogxK
U2 - 10.1002/chir.22741
DO - 10.1002/chir.22741
M3 - Artículo
C2 - 28840973
SN - 0899-0042
VL - 29
SP - 716
EP - 725
JO - Chirality
JF - Chirality
IS - 11
ER -