Aromatic plants of tropical Central Africa. Part XXXI. Tricyclic sesquiterpenes from the root essential oil ofEchinops giganteus var.lelyi C. D. Adams

Total Synthesis of (±)-Cameroonan-7α-ol and Biomimetic Rearrangements to Related Nopsane Sesquiterpenes

“…Weyerstahl and co-workers recently reported the isolation of three new sesquiterpene alcohols, (−)-cameroonan-7α-ol ( 6 -OH), (+)-prenopsan-8-ol ( 7 ), and (−)-nopsan-4-ol ( 8 ), from the essential oil of Echniops giganteus var lelyi rhizomes . These natural products were isolated from a complex mixture of numerous biogenetically related silphinanes including five of the eight possible silphiperfolan-6-and 7-ols, one being the previously known (−)-silphiperfolan-7β-ol, 9 .…”

“…The structures and relative stereochemistry of these natural products were assigned mainly by NMR spectral methods . The absolute configurations shown were based on the co-occurrence with silphinane sesquiterpenes of known configuration (e.g.…”

Enantioselective Total Synthesis of the Reported Structures of (−)‐9‐epi‐Presilphiperfolan‐1‐ol and (−)‐Presilphiperfolan‐1‐ol: Structural Confirmation and Reassignment and Biosynthetic Insights

“…Although the presilphiperfolanols have garnered broad scientific interest in the natural product, [xiii] biosynthesis, [iii, ix, xii, xiv, xv] organic synthesis, [xvi, xvii] computation, [viii] and fragrance [viia, xvi, xviii] literature since their discovery, they have proven to be challenging targets for total synthesis. To date, only (±)-presilphiperfolan-9-ol ( 4 ) has been prepared by total synthesis, [xvi] and no asymmetric routes toward any of the presilphiperfolanols have been reported.…”

Biosynthesis and Chemical Synthesis of Presilphiperfolanol Natural Products

“…As a relatively nonpolar low molecular weight alcohol, presilphiperfolan-9α-ol ( 2 ) has pleasant olfactory properties and has attracted interest as a fragrance compound. [2, 22] The natural product (−)- 2 [2] has a pleasantly sweet and woody aroma with hints of coconut and celery. Synthetic (±)- 2 [8] possesses a slightly different olfactory profile with a strongly radiative, woody, resinous, and amber(gris) notes.…”