First enantiospecific synthesis of marine nor-sesquiterpene (+)-austrodoral from (−)-sclareol

Secondary Metabolites from Polar Organisms

“…A role of stress-metabolites could be suggested for these compounds [84]. A short and efficient synthesis of 144 and 145 was reported as shown in Scheme 7 [85]. Further chemical study of this Antarctic nudibranch yielded two novel 2-monoacylglycerols ( 146 ) and ( 147 ) (Figure 15), along with two known 1,2-diacyl glyceryl esters [86].…”

Diterpenoids

“…18 Readily available labdanes have continued to provide useful chiral starting materials for partial synthesis. There have been reports of the synthesis of the marine norsesquiterpene (+)austrodoral from sclareol, 19 (−)-Thioambrox R from sclareolide, 20 6b-isovaleryloxylabda-8,13-diene-7a,15-diol from larixol, 21 (−)marginatone from (+)-coronarin E, 22 and the sesterterpenoid luffolide from methyl isocopalate. 23 Some Michael adducts to unsaturated ketones derived from readily available hispanolone have shown 24 useful activity against the rice blast fungus, Magnoporthe grisea (Pyricularia oryzae).…”

Cold-water marine natural products

“…191 Further, A. kerguelenensis elaborates two novel nor-sesquiterpenes, austrodoral (229) and austrodoric acid (230), 194 both of which have been synthesized. 195,196 The pteropod Clione antarctica, a shell-less, pelagic mollusc, was found to contain a defensive polyketide metabolite, pteroenone (231). 197 A new synthesis of all four stereoisomers has confirmed the structural assignment.…”

“…159 Interestingly, it was found that flustrarine B could be reversibly converted to flustramine B N-1-oxide (194) upon treatment with acid. 159 Flustramine E (195), which displays activity against Botrytis cinerea and Rhizotonia (= Rhizoctonia?) solani, 160 and debromoflustramine B derivative 196, were obtained from a Danish collection of the bryozoan.…”