Carbon‐13 nuclear magnetic resonance spectra of some tetracyclic diterpenoids isolated from Elaeoselinum species

Abstract

The I3C nuclear magnetic resonance (NMR) spectral data for nine ent-kaurenes, 12 ent-beyeranes and four ent-atisene derivatives, isolated from Elaeoselinum species, are discussed. The assignments of the "C signals were based on DEPT sequences, two-dimensional (2D) 6H/K NMR spectra and comparison with known compounds.The assignments of some known ent-kaurenes are revised

Total Syntheses of (±)-Isosteviol and (±)-Beyer-15-ene-3β,19-diol by Manganese(III)-Based Oxidative Quadruple Free-Radical Cyclization

“…The 1 H NMR spectral data for 4 are identical to those reported for the natural product . The 13 C NMR spectral data for 4 correspond appropriately to those reported for beyer-15-ene, beyer-15-ene-19-ol, and beyer-15-en-3β-ol. − …”

“…Reaction of keto diol 39 with TsNHNH 2 gave 51% of tosylhydrazone 41 , which was treated with 20 equiv of n -BuLi to provide 64% of beyer-15-ene-3β,19-diol ( 4 ). The structure of 4 was established by the identity of the 1 H NMR spectral data to those of the natural product 6 and the similarity of the 13 C NMR spectral data to those of closely related beyer-15-enes. − Diol 4 was prepared from 2 in 4 steps in 17% overall yield.…”

Structure of Kaurane-Type Diterpenes fromParinari spruceiand their Potential Anticancer Activity

“…To the best of our knowledge, diterpenes 1 ± 20 are new natural products. The known compounds 21 ± 23 were identified, by analysis of their spectroscopic data and comparison with those reported in the literature, as 13-hydoxy-15-oxozoapatlin (21) [3], 16a,17-dihydroxy-ent-kauran-19-oic acid (22) [15], and entkaur-16-en-19-oic acid (23) [16].…”

Chemical Composition of Aerial Parts Essential Oils from Six Endemic Malagasy Helichrysum Species

“…We highlighted the identification of presilperfolane and silphiperfolane derivatives as major components in the three samples by comparison of their carbon chemical shifts values with those reported in the literature [16][17][18][19][20][21][22]: 7-epi-silphiperfol-5-en-13-oic acid (4.0-20.8%) and silphiperfol-5-en-13-oic acid (4.0-10.6%) ( Table 2), 7-epi-subergorgiol (7.6-14.8%), 7β-H-silphiperfol-5-ene (1.8-14.8%), presilphiperfolan-9-α-ol (6.9-8.0%), 7-epi-silphiperfolenal (1.4-2.5%), 13-hydroxysilphiperfol-6-ene (1.2-1.9%) and 7α-H-silphiperfol-5-ene (up to 0.3%). The presence of a compound including an acid group as major component is very unusual in essential oils.…”