Nujol77ququ.com

J.
C.
S.
CHEM.
COMM.
,1977555StructureofIsodomedin,aNovelent-KaurenoidDiterpeneByISAOKUBO,*IWAOMIURA,andlKoJINAKANISHI(DepartmentofChemistry,ColunzbiaUniversity,NewYork10027)TADAOKAMIKAWAandTAKAHIKOISOBE(FacultyofScience,OsakaCityUniversity,Sumiyoshi-ku,Osaka558,Japan)andTAKASHIKUBOTA(SchoolofMedicine,KinkiUniversity,Sayama-cho,Osaka589,Japan)SummaryChemicalinvestigationofbitterprinciplesfromIsodonskikokianusvarintermediushasledtotheisolationandcharacterizationofanewent-kaurenoid,isodomedin,whichexhibitsantibacterialandcytotoxicactivitiesaswellasantifeedantactivityagainsttheAfricanarmyworm.
INthecontinuingsearchforbiologicallyactivediter-penoidsoftheIsodonspecies,lwehaveexaminedI.
shiko-kianusvarintervnedius,fromwhichanewantibacterialandcytotoxicprinciple,tisodomedin,m.
p.
217-218OC,hasbeenisolatedin0-0004~0yieldfromdryleaves.
Isodo-medinexhibitedantifeedantactivityagainstthelarvaeoftheAfricanarmyworm,Spodopteraexenzpta.
Wenowproposetheent-kaurenoidstructure(1)forthisbitterprinciple.
Isodomedin,whichiscloselyrelatedtokamebanin(2),isolatedfromI.
kameba,givesthefollowingdata:C,,H,,O,(highresolutionm.
s.
andelementalanalysis),59"(C1.
0,EtOH);Amax(EtOH)233.
5nm(E8020);Vmax(Nujol)3570and3420(OH),1710and1270(OAc),and1700and1650cm-l(5-memberedringketoneconjugatedwithexocyclicmethylene).
The13Cn.
1n.
r.
dataofisodome-din(Figure1)showedthepresenceof3xMe,1xAc,4xCH,,7xCHgroups,andthreetetrasubstitutedcarbonatomstogetherwithtwoolefinicandtwocarbonylcarbonatoms.
3$Thecytotoxicity(KB)effect(LD,,)was4.
0pgml-l.
Thedetailedstudywillbepublishedelsewhere.
Theresultsarebasedonacombinationofproton-noisedecoupling,off-resonancedecoupling,andFouriertransformoff-resonancedecouplingtechniques,(P.
Zanno,I.
Miura,K.
Nakanishi,andD.
Elder,J.
Amer.
Chem.
Soc.
,1975,97,1975).
556J.
C.
S.
CHEM.
COMM.
,1977FIGURE1.
solution.
Isodomedin;13Cn.
m.
r.
data(6/p.
p.
m.
)forC,D,NThepertinent1Hn.
m.
r.
dataareshowninFigure2;thegrossstructureofringsA-B-cwasestablishedbyobserva-tionofanuclearOverhausereffect(n.
0.
e.
)on10-Meuponirradiationofthe14~-Hsignal.
Dihydroisodomedin(3),obtainedfromcatalytichydrogenationof(l),hasanegativec.
d.
(MeOH)AE.
,,,-0.
86andhencetheD-ringisJQ-~riented.
~Highresolutionelectronimpactmassspectrometryofisodomedinshowedpeaksatm/e194and176whichwereformedbycleavageoftherring.
^Comparisonofthe13CandlHn.
m.
r.
spectraofisodomedinwiththoseofkame-baninindicatedthattheonlydifferencebetweenthesetwocompoundswasanadditionalacetoxygroupintheA-ringofisodomedin.
TheddsplittingpatternoftheCH-OHsignal(63-86)showedthatamethylenegroupwasadjacenttothisprotonandthusthatthehydroxygroupshouldbeattachedeithertoC-1orC-3.
TheJvaluesofthisddsignal(10and6Hz)showedthehydroxygrouptobeequatorial,Todeterminethepositionoftheacetoxygroup,n.
0.
e.
studieswereperformedon(5).
Observationofa10%n.
0.
e.
on18-Meuponirradiationoftheoriginal-CH-OAcsignal(whichiseasilydistinguishedfromotherprotonsonthecarbonatomsbearinganacetoxygroupbytheircouplingconstants)revealedthattheacetoxygroupin(1)isatthe3position.
Itisclearthatthisgroupis/&orientedfromthevaluesofJ201,3a=Jzp,3a=3Hz.
The1,15-dione(4)wasderivedbyoxidationof(3)withJones'reagent.
The7-andlkhydroxygroupswerenotoxidizedundertheseconditionsbecauseofintermolecularH-bonding.
Inthe13Cn.
m.
r.
spectrumof(4),thedoubletresonanceofC-1wasreplacedbyasingletandtheC-2andC-10signalshadundergonetheexpecteddownfieldshiftsoftheadjacentC-1ketonegroup.
Thenegativecad.
(MeOH)kso0-1.
80of(4)wasalmostidenticalwiththatofthe1,15-dione(6)whichhadbeenobtainedfrom(2)inasimilarmanner.
groupatthe1position.
Thissupportstheassignmentofthehydroxy351(dd,135,551FIGURE2.
multiplicityandJvalues(inHz)inparentheses.
lHn.
m.
r.
datafor(1);C5D5Nsolution;Svalues;Thestructurewasconfirmedbycorrelationwithkame-banin(2).
Thehydroxygroupof(4)wasprotectedwithphenylboricacid,followedbytreatmentwithh-K,CO,in50%aq.
MeOHtogiveanenone(7).
Thiswasthenhydrogenatedtoyieldadeacetyldione(8),whichwasidenticalinallrespectswiththecompoundderivedfrom(2)inasimilarmanner.
(6)R=H(8)RR=>BPhThisworkwaspartlysupportedbytheN.
I.
H.
(Received,19thMay1977;Cow.
486.
)E.
Fujita,Y.
Nagao,andM.
Node,Heterocycles,1976,5,793andreferencescitedtherein.
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