Guaiane dimers from Xylopia vielana

Abstract

From the leaves of Xylopia vielana (Annonaceae) two dimeric guaianes named vielanins D and E were isolated and structurally elucidated by mass and NMR spectroscopy. Vielanin D and E consist of bridged ring systems formally representing the Diels-Alder products from the hypothetical guaiane-type monomers. Due to a hemiketal function at C-8' both compounds occurred as epimeric mixtures.

Peroxy natural products

“…Both compounds consist of bridged ring systems formally representing the Diels-Alder products from the hypothetical guaiane-type monomers. 199 Spicachlorantins C-F 350-353, new lindenane sesquiterpene dimers possessing a hydroperoxy group, were isolated from the roots of Chloranthus spicatus, whose absolute stereostructures were established by CD spectroscopic analyses. These compounds were considered to be biogenetic precursors of the corresponding hydroxyl derivatives of dimeric lindenane sesquiterpenoids distributed in Chloranthus plants.…”

Antiproliferative Sesquiterpenes from the Red Sea Soft Coral Sarcophyton Glaucum

“…The relative stereochemistry of 4 was based on NOESY data and by comparing the 1 H and 13 C proton chemical shifts and coupling constants (Js) with those of Xylopia guaiane dimers. This comparison led to the assignment of H-9a (δ 2.10, dd, J = 13.5, 5.2 Hz) as α-oriented [5]. H-9a also showed a strong NOESY correlation with H 3 -15, indicating the α orientation of this methyl group.…”

“…The guaiane moiety accounted for two out of three rings, and the third ring was then assigned as a 1,2-dioxolane ring between C-7 and C-8. Recently, plant-derived guaiane dimers with similar 1,2-dioxolane-3-ol moieties were reported from Xylopia species [5]. The relative stereochemistry of 4 was based on NOESY data and by comparing the 1 H and 13 C proton chemical shifts and coupling constants (Js) with those of Xylopia guaiane dimers.…”

Xylopins A–F, six rare guaiane dimers with three different connecting modes from Xylopia vielana

“…The genus Xylopia, which is one member of the family Annonaceae, whose bark and leaves are used for the treatment of irregular menstruation, rheumatism and pain. 1 So far, phytochemical studies of the genus Xylopia led to the identication of nearly 80 compounds, such as avonoids 2,3 steroids, 4 sesquiterpenes, 4 alkaloids, [5][6][7][8] diterpenes, 9-11 diterpene dimers 10,12,13 and sesquiterpene dimers. 14,15 In a continuing search for biologically active compounds from X. vielana, six rare guaianetype sesquiterpene dimers, having three different connecting patterns between two guaiane-type sesquiterpene, were isolated ( Fig.…”

“…Xylopin A(1). Colorless prismatic crystal; [a]20 D À16.5 (c 0.10 CH 2 Cl 2 ); IR (KBr) n max 3446, 2956, 2911, 2869, 2850, 1688, 1462, 1377, 1026, 668 cm À1 ; for 1 H-NMR and 13 C-NMR spectroscopic data, seeTable 1; HRESIMS (positive): m/z 513.2977 [M + Na] + (calcd for 513.2975).…”