Ilicic Acid as a Natural Quiron for the Efficient Preparation of Bioactive α‐ and β‐Eudesmol

Abstract

An efficient procedure for the isolation of the sesquiterpene ilicic acid (3) on a multigram scale of extracts obtained from aerial parts of Inula viscosa (Asteraceae) was developed. Acid 3 is an appropriate starting material for short, enantiospecific syntheses of β‐eudesmol (1) and α‐eudesmol (2), natural products featuring significant antiangiogenic and anti‐Alzheimer properties. Synthesis of 1 was achieved in six steps and the synthesis of 2 in seven, producing overall yields of 52 and 41 %, respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

New Sesquiterpenes from the Flowers of Chrysanthemum indicum L.

“…We now unambiguously assigned all the H-and C-atoms of 3 and 5 by analysis of the 1D-and 2D-NMR spectra including 1 H, 1 H-COSY, HSQC, HMBC, and NOESY data (Tables 1 and 2). Bohlmann and Knoll suggested that the endoperoxide moiety in 5 was b-oriented, while the NOESY correlations between Me(15), Me (14), and HÀC(6) strongly suggested that the endoperoxide moiety in 5 was a-oriented, which well agreed with the result reported by Ognyanov and co-workers in 1981 [8]. In addition, Ognyanov and co-workers have also reported the isolation and structural elucidation of C-NMR data were completely identical to those of compound 4.…”

“…Phytochemical investigation of the flowers of C. indicum led to the isolation of two new guaianolide (¼ guaianolactone) sesquiterpenes, named chrysanthguaianolactone A 1 ) (1) and chrysanthguaianolactone B 1 ) (2), and one new eudesmane sesquiterpene, named chrysanthemdiol A 1 ) (6), together with seven known sesquiterpenes. By comparison of their spectroscopic data with those reported, the known compounds were elucidated as (3a,6a,8a)-8-tigloyl-3,4-epoxyguai-1(10)-eno-12,6-lactone (3) [7], apressin (4) [8], athanadregeolid (5) [9], cumambrin A [10] [11], (3b,6b)-eudesm-4(14)-ene-3,5,6,11-tetrol [12], (þ)-eudesm-4(14)-ene-11,13-diol [13] [14], and cryptomeridiol [15]. Herein, we report the isolation and structural elucidation of the new compounds.…”

1-[(2R,4aR,8R,8aR)-8-Hydroxy-4a,8-dimethylperhydronaphthalen-2-yl]ethan-1-one

“…For the synthesis, see: Barrero et al (2009). For the medicinal interest in Inula Viscosa (L) Aiton [or Dittrichia Viscosa (L) Greuter], see : Shtacher & Kasshman, (1970); Bohlmann et al (1977); Chiappini et al (1982) and for the pharmacological interest, see: Azoulay et al (1986); Bohlmann et al (1977); Ceccherelli et al (1988).…”

Transannular Cyclization of (4<i>S</i>,5<i>S</i>)-Germacrone-4,5-epoxide under Basic Conditions to Yield Eudesmane-Type Sesquiterpenes

“…Germacrane-type compounds having ten-membered rings are important intermediates during the biosynthesis of sesquiterpenes having multi-ring carbon skeletons via T-A cyclization. [4][5][6][7] Germacrane intermediates convert to polycyclic terpenes such as eudesmane, guaiane, pseudoguaiane, eremophilane, and vetispyrane.…”

“…13,16,17) However, there have been few reports on T-A cyclization performed under basic conditions. 17) We treated 1 under basic conditions to yield four products (2)(3)(4)(5). Two (4, 5) of them were new compounds.…”