Eudesmanolide derivatives

Arborescin (586), a metabolite of Artemisia arborescens, has been synthesized (Scheme 59) from the eudesmanolide derivative (421) previously used in the synthesis of vulgarin " cf. p. 128). 

Eudesmanes and eudesmanolide derivatives 89-93 isolated from or chemically obtained from isolated terpenes from Sideritis sp. have been used for biotransformation by Curvularia lunata or Rhizopus nigricans. Beside (sometimes predominant) reduction reactions, hydroxylations occur in substantial yields at the methyl groups of the side chain in 89 [121] C-1, C-2, and C-4 of the A ring in 90 and 91 [122], and on various positions such as C-1, C-4, or C-8 in 92 [123] and 93 [124,125]. 

Vol. 5, p. 76). Related studies have shown that the butenolide derivative (319) can be used as an annulating agent in the construction of linear tricyclic y-lactones [cf. (322) and (323)] and it is expected that this methodology may be applied to the synthesis of naturally occurring eudesmanolides." ... 

Eudesmanolide sesquiterpene lactones (G6 G6 C40L) include a variety of variously cytotoxic compounds. The antifeedants alantolactone and isoalantolactone (helenin being a mixture of the two) (C6 ] C5 C40L=CH2) are antimicrobial. The pro-apoptotic activity of these compounds may derive from the reactivity of the a-methylene-y-butyrolactone ring... 

Synthesis of 6,12-sesquiterpenolides This section describes the synthesis of sesquiterpenes bearing a lactone moiety between C(6) and C(12). The transformation of the A-ring in santonin to give eudesmanolides, guaianolides, and elemanolides, as well as the modification of the lactone ring is described. Some microbiological transformations of santonin and its derivatives are also described. 

Several struetural variants of laetones derived from eudesmane oceur in Artemisia-species (Asteraeeae). These include various 3-oxo-12,6-eudesmanolides such as (+)-santonane from the flowers of A. pauciflora, (-)-taurin from A. taurica (not to be confused with taurine = 2-aminoethanesulfonic acid) and the antihelmintic but toxic santonines isolated from the dried unexpanded flowerheads of A. maritima (contents up to 1.5% of a-santonin) and allied species. 

Cryptomeridiol (227) is a fully saturated eudesmane from heartwood of Cryptomeria japonica (381). From the heartwood of red sandal (Pterocarpus san-talinus) a number of eudesmanes have been isolated, of which pterocarpdiolone (228) may be mentioned (246). Costic acid (229), a eudesmane acid, is present in costus root oil (30). Laevojunenol (230) from vetiver oil (Vetiveriazizanioides) of North Indian origin is an example of e t-eudesmane derivative (345). Of the many presently known eudesmanolides only a few have been isolated from woody parts of plants (+)-dihydro-/8-cyclocostunolide (231) was obtained from trunkwood of Moquinea velutina (146). 

Bohlmann, F., C. Zdero, R.M. King, and H. Robinson Eudesmanolides and kaurane derivatives from Wedelia hookeriana. Phytochem. 21, 2329 (1982). 

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