A convenient synthetic method of 2‑substituted indoles and its applcation for the synthesis of natural alkaloid, borrerine
著者 Somei Masanori, Sayama Shinsuke, Naka Katsumi, Yamada Fumio
journal or
publication title
Heterocycles
volume 27
number 7
page range 1585‑1587
year 1988‑01‑01
URL http://hdl.handle.net/2297/4313
HETEROCYCLES,Vol27,No.7,7988
ACONVENエENTSYNTHETエCMETHODOF2-SUBSTエmUmEDエNDOLESANDエTS
APPL工CATエONFORTHESYNTHESエSOFNATURALALKALOエD,BORRERエNE1
MasanoriSomei,*ShinsukeSayama,KatsumiNaka,andFumioYamada FacultyofPharmaceuticalSciences,KanazawaUniversity
l3-1Takara-machi,Kanazawa920,.apa、
Abstract-Asimp1esyntheticmethodof2-substituted indolesisdeveloped・TotalsynthesisoEnaturalalkaloid,
borrerine,isalsoreported.
mthiscommunication,wedescribeaversat1letwostepsYntheticmethodwhichcan providesynthetica11yuseful2-substitutedindoles,anditsaPP1icationforthe
synthesisofnatura1alkaloid,borrerme(7c).2 ~
commerciallyavailable2-oxindole(1)ledto2-bromo-3-indo1ecarboxaldehyde(2) ~ ヘグ
in77gyieldaccordin9toSchulte’sprocedure、3エnordertointroduceacarbonside chaindirect1yintothe2-position○だ2,improvedHeckreaction4a’b seemedtobe
へ夕
4a-dHowever,
promisingamongvariouspalェadiumcatalyzedcrosscouP1ingreactions.
R3Sn-R1
CR]〔:iLLCEi。〔;vo
r
○TLo-
H 。「、‐LOHP-B,lKCOOMeP-B
1}
02
○甲
H 、=Ndl-〃
’3
、
0 H
6 - 5 ヘヴ
、
l-c【】【
-1585-
theHeckreactiono定2with2-methyl-3-buten-2-oエproducedthedesired2-(3-hydroxy-
~3-methy1-1-buten-1-yl)-3-indolecarboxa1dehyde(3a,、p190.5-193.C)inpooryield
~andtheyie1dcouldnotbeincreasedabovel58unde]ごvariousreactionconditions・
Ontheotherhand,modiどiedStil1e'sreaction4cwasだ。undtomeetourend・Thus,3a~
wasobtainedin878yiLe1dbythereactionof2with(3-hydroxy-3-methyエーユーbuten-l-~
yl)tributy1tin(4a)5inthepresenceoftetra-n-butylalnInon1umchlorideandacata-
~lyticamount。fpal1adiumacetate・Similarly,thereactionof2vvithtinreagents,
~suchas4b,64c,4.,74e,and4f,7afEorded3b(mp26エー262°C),3c(mp260.5-263°C),
~ ~~ ~ ~ ~ ~3.(mp246-246.5°C),3e(mp207-208.5°C),and3f(mp226-227oC)in678,688,388,
タレ ヘク ~398,and58yields,respective1y・Zknattempttoimprovetheyieldof3fiscur-
~rentlyunderinvestigation・
Withthedesiredbui1dingblocks(3a-f)forvarious2-substitutedindolesinhand,
〃、=~wenexttriedatota1synthesisofborrerine(7c).2First,3awasconvertedto5
nヴ グレ ~(mp246-247oC)in86号yieldbythereactionwithnitromethaneinthepresenceof ammoniumacetate・Subsequentreductionof5withsodiumborohydrideinmethano1ar-
~Eorded6(mp122-123oC)in80gyield・Next,ourreductiveaminocyclizationmethod8
いず(reE1uxingwithzincinmethanolichydroch1。ricacid)wassuccessEu11yapp1iedto6
~affording酉(、p162-164°C,1it、2bmp158-159oC)in508Yie1d・Treatmentof7awith
~methy1chloroformategave858yieldof7P(mp188.5-189°C,1it、2bmpl80-181oC),
whichfina11yエedtoborrerine(7s,、p107-108°C,1it、2bmp1O2-103oC)in708
yie1dbythereductionwith1ithiumaluminumhydrideinanhydroustetrahydrofuran・
Spectraldataof7cwereidenticalwiththoseofborrerinewhichwassynthesizedby
~2b'9 Sakaiandco-workers・
Bioエ。gica1evaluationsofnewcompoundsandthetota1synthesisoEotherreエated naturalalkaloidsarecurrentlyinprogress.
ACKNOWLEDCEMENT
TheauthorsexpresstheircordiaエgratitudetoProf.S・Sakai,ChibaUniversity,
造。rkind1ysendingusspectraユdataandauthenticsampユeofborrerine.
REFERENCESANDNOTES
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-1586-
HETEROCYCLES,Vol2ZNo.Z7988
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ヘグーー-
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デー
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8.
穴シ
Bull.,33,2162(1985). PLP
9.ldixedmeltingpointoE7candborrerineshowednodepressユ。n.Borrerineand7cAP へ>
meltedonceatabout57--59oCandgraduallysolidiだied,andthenfinallymelted
atlO7-108oC.
Received,11thNarch,1988
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