81924-60-9Relevant articles and documents
Biosynthesis of Rotenoids by Amorpha fruticosa: Sequence, Specificity, and Stereochemistry in the Development of the Hemiterpenoid Segment
Crombie, Leslie,Holden, Ian,Kilbee, Geoffrey W.,Whiting, Donald A.
, p. 789 - 798 (2007/10/02)
By isolation and radiochemical methods rot-2'-enonic acid, dalpanol, rotenone, and amorphigenin have been identified in Amorpha fruticosa seedlings, and ordered in biosynthetic sequence.Its specific activity shows that 12aβ-hydroxyamorphigenin has origins other than direct 12aβ-hydroxylation of amorphigenin: its occurrence and labelling establish it as a true natural product.Except for isopentenyl alcohol, the potential hemiterpene precursors mevalonic acid, 3-hydroxy-3-methylglutaric acid, and dimethylallyl alcohol are poor precursors for amorphigenin.By employing the already prenylated (E)-rot-2'-enonic acid, it is shown that the 4'-C of this compound becomes 7'-C of rotenone.By assuming normal rear-side attack on an intermediate epoxide, and utilising the known absolute configurations at position 5' of dalpanol and rotenone, a stereochemical sequence can be written. (E)-4'-Labelled rot-2'-enonic acid leads to a (2'S,3'S)-epoxide, which on intramolecular attack by phenolate anion would give (5'R,6'S)-dalpanol, dehydration to rotenone then involving the labelled (pro-S)-7'-methyl group of dalpanol.Neither (6'R)- nor (6'S)-amorphigenol is a precursor of amorphigenin.Administration of rotenone to A. fruticosa seedlings has led, in three experiments designed to avoid inadvertent chemical scrambling of the allylic label, to amorphigenin having even label distribution between C-7' and C-8'.Possible interpretations are considered.
