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Dovyalicin-Type Spermidine Alkaloids from Dovyalis Species
dataset
posted on 2006-09-22, 00:00 authored by Bonnie Rasmussen, Aimee-Justine Nkurunziza, Matthias Witt, Hellen A. Oketch-Rabah, Jerzy W. JaroszewskiPhytochemical investigations of Dovyalis abyssinica, D. hebecarpa, and D. macrocalyx revealed two new spermidine-type alkaloids, dovyalicin E (3) and dovyalicin F (4), along with the previously described dovyalicin A (1), dovyalicin
B (2), and dovyalicin C (5). In addition, a new phenol glucoside, 4-hydroxytremulacin (7), and the new 1,2-cyclohexanediol
glucoside 9, as well as the known compounds methyl 1-hydroxy-6-oxocyclohex-2-enecarboxylate (6) and tremulacin
(8), were isolated. The structures were established using homo- and heteronuclear two-dimensional NMR experiments
and chiroptical methods. At ambient temperature, the N-disubstituted amide 4 exists as a mixture of cis and trans
conformers. Variable-temperature 1H NMR studies showed that time-averaged spectra are obtainable at 348 K, and the
activation parameters determined for the rotation about the amide bond were ΔH⧧ = 89 ± 4.6 kJ/mol, ΔS⧧ = 65 ± 14
kJ/mol·K, and ΔG⧧(298K) = 70 ± 4.5 kJ/mol.