Pseudoguaianolides

The two pseudoguaianolides confertiflorin (17) and its desacetyl derivative (18), both Isolated from A. confertlflora, show considerable differences in activity. Sorghum (87%) and ryegrass (86%) are inhibited and wheat (111%), clover (112%) and Palmer amaranth (111%) are promoted by 17. To the contrary, ryegrass (114%) is promoted by 18 while most other seeds show little effects. 

Lee HT, Yang SW, Kim KH, Seo EK, Mar W. Pseudoguaianolides isolated from Inula britannica var. chinenis as inhibitory constituents against inducible nitric oxide synthase. Arch Pharm Res 2002 25 151-153. 

Perhydroazulenones.2 The key step in a synthesis of carpesiolin (3), a pseudoguaianolide lactone, is a regioselective ring expansion of a perhydroindanone (i) to 2 by dibromomethyllithium. 

Synthetic entry into the pseudoguaianolide skeleton has finally been achieved.128 The known hydroazulenol (296) was used as starting material and converted into ( )-4-deoxydamsin (297) by the series of simple functional-group transformations outlined in Scheme 32. 

Ligulatin B (= Incanin) (pseudoguaianolide sesquiterpene lactone) Parthenium ligulatum, P. spp. (Asteraceae) Insect antifeedant... 

P h y t o c h e m i c a l investigations of plant species of Parthenium, Encelia and Pi coria (Asteraceae) from semi-arid and arid zones of the United States and Mexico has resulted in the isolation and identification of numerous sesquiterpene lactones and benzopyrans that are active insect feeding deterrents. The chemistry, biological effects and possible mode of action of bioactive pseudoguaianolides and chromenes are reviewed. 

In an attempt to induce a rearrangement to give the pseudoguaianolide (621) the epoxy-alcohol (620) was treated with boron trifluoride etherate. An X-ray analysis, however, has shown that one of the major products is the fluoro-alcohol (622). ° A number of new xanthanolides, grafininacetate (623), desacetyl-xanthanol (624), and xanthanolacetate (625) have been isolated from Pulicaria crispa. These compounds co-occur with the unusual seco-eudesmane sesqui-terpenoid, secocrispiolide (626). 

Cycloheptane derivatives (7, 192-193). Wender et a/. have applied their cycloheptane annelation procedure to total syntheses of the pseudoguaianolides damsinic acid (1) and confertin (2). The paper describes the synthesis of 1-lithio-l-methyl-2-vinylcyclopropane, which is the annelation reagent utilized in the pseudo-guaianolide syntheses. 

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