Corrigendum to “Chemical and genetic diversity of Ligularia virgaurea collected in northern Sichuan and adjacent areas of China. Isolation of thirteen new compounds” [Tetrahedron 68 (2012) 10011–10029]

Terpenoids from Ligularia virgaurea collected in China: the first example of two bakkane derivatives with an anhydride-type ring C and nineteen new chemical constituents

“…We previously reported that the species collected in the Sichuan, Qinghai, and Gansu provinces were grouped into the following five chemotypes on the basis of their terpenoid constituents: L-type (the major component was ligularol), V-type (virgaurenone A), C-type (cacalol), H-type (6-hydroxyeuryopsin), and N-type (neoadenostylone). [2][3][4] The species were grouped into three clades on the basis of their DNA sequences, which were in good agreement with the chemotypes (clade A = L-type, clade B = V-and H-types, clade C = C-and N-types). In addition to furanoeremophilanes, the major components, we previously isolated a variety of new compounds such as seco-eremophilanes, bakkanes, and compounds having further rearranged carbon skeletons from 38 samples of L. virgaurea.…”

“…The molecular formulae of compounds 13−16 were determined to be C20H24O6, C19H24O6, C17H20O6, and C15H18O5, respectively by HRCIMS and 13 C NMR data. All compounds exhibited an IR absorption band at approximately 1809 cm -1 and were deduced to be an epoxy-or an enol-lactone, 2,3,8 which was supported by the presence of quartet signals at δ 2.49-2.83 (J = 7.1-7.3 Hz) assignable to H-11 in the 1 H NMR spectra ( Table 5). The 2D correlations shown in Fig 7 indicated that these compounds were epoxy-lactones with 1(10)-en-2-one structures.…”

“…The observed value was at a slightly higher wavenumber than that at which an epoxy-and an enol-lactone have ever been encountered. 2,3,8 The 13 C NMR spectrum indicated the presence of five methyl, two methylene, five methine, and eight quaternary carbon atoms including eight sp 2 carbon atoms (four carbonyl and four olefinic carbons). The degree of unsaturation was 9, and therefore, this compound should be tricyclic.…”

“…In addition to furanoeremophilanes, the major components, we previously isolated a variety of new compounds such as seco-eremophilanes, bakkanes, and compounds having further rearranged carbon skeletons from 38 samples of L. virgaurea. 3 Various sesquiterpene dimers were also isolated. [3][4][5][6][7] Since then, four new compounds, including rearranged norsesquiterpenes, were characterized from another sample.…”

“…3 Various sesquiterpene dimers were also isolated. [3][4][5][6][7] Since then, four new compounds, including rearranged norsesquiterpenes, were characterized from another sample. 8 We have analyzed two more samples (one from northern Sichuan province and the other from southern Gansu province) 3 and 26 compounds were isolated, 21 of which were new.…”