C3-Selective alkenylation of N-acylindoles with unactivated internal alkynes by cooperative nickel/aluminium catalysis

Article abstract of DOI:10.1039/c7cc00852j

Highly regio- and stereoselective alkenylation of N-acylindoles with unactivated internal alkynes has been accomplished by cooperative nickel/aluminium catalysis to afford C3-alkenylated indoles. Coordination of the acyl moiety to a bulky aluminium-based Lewis acid plays a crucial role in the selective functionalization at the C3-position by electron-rich nickel(0) catalysis.

Full text of DOI:10.1039/c7cc00852j

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Marilyn M. Olmstead, Alan L. Balch, Josep M. Poblet, Luis Echegoyenet al.
Reactivity differences of Sc
first methanofullerene derivatives of Sc
3
N@C2n (2n
=
68 and 80). Synthesis of the
3
N@D5h-C80
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Pleaseꢀd Co hꢀ ne omt ꢀ Ca do j mu smt ꢀmarginsꢀ
View Article Online
DOI: 10.1039/C7CC00852J
JournalꢀNameꢀ
COMMUNICATIONꢀ
ꢀ
C3-SelectiveꢀAlkenylationꢀofꢀN-AcylindolesꢀwithꢀUnactivatedꢀ
InternalꢀAlkynesꢀbyꢀCooperativeꢀNickel/AluminiumꢀCatalysisꢀ
Receivedꢀ00thꢀJanuaryꢀ20xx,ꢀ
Acceptedꢀ00thꢀJanuaryꢀ20xxꢀ
ꢀ
ꢀ
DOI:ꢀ10.1039/x0xx00000xꢀ
www.rsc.org/ꢀ
*
FumiyoshiꢀInoue,ꢀTeruhikoꢀSaito,ꢀKazuhikoꢀSemba,ꢀandꢀYoshiakiꢀNakao ꢀ
Theꢀhighlyꢀregio-ꢀandꢀstereoselectiveꢀalkenylationꢀofꢀN-acylindolesꢀ substratesꢀforꢀalkenylationꢀofꢀindolesꢀbefore.ꢀ
withꢀ unactivatedꢀ internalꢀ alkynesꢀ hasꢀ beenꢀ accomplishedꢀ byꢀ
TheꢀstudyꢀwasꢀcommencedꢀwithꢀtheꢀreactionꢀofꢀN-benzoylindoleꢀ
4
h
cooperativeꢀ nickel/aluminiumꢀ catalysisꢀ toꢀ affordꢀ C3-alkenylatedꢀ (1a) ꢀandꢀ4-octyneꢀ(2a)ꢀinꢀtheꢀpresenceꢀofꢀNi(cod)2ꢀ(10ꢀmol%)ꢀandꢀ
i
indoles.ꢀ Coordinationꢀ ofꢀ theꢀ acylꢀ moietyꢀ toꢀ aꢀ bulkyꢀ aluminium- PPr3ꢀ(10ꢀmol%)ꢀinꢀtolueneꢀatꢀ80ꢀ°CꢀtoꢀaffordꢀaꢀmixtureꢀofꢀC3-ꢀandꢀ
basedꢀ Lewisꢀ acidꢀ playsꢀ aꢀ crucialꢀ roleꢀ forꢀ theꢀ selectiveꢀ C2-substitutedꢀ cis-alkenylationꢀ productsꢀ 3aaꢀ andꢀ 4aaꢀ inꢀ 8%ꢀ
functionalizationꢀ atꢀ theꢀ C3-positionꢀ byꢀ electron-richꢀ nickel(0)ꢀ combined yieldꢀ (Tableꢀ 1,ꢀ entryꢀ 1).ꢀ Theꢀ stereochemistryꢀ ofꢀ theꢀ
1
catalysis.ꢀ
productsꢀwereꢀconfirmedꢀbyꢀtheꢀnOeꢀexperimentsꢀofꢀ HꢀNMRꢀ(Seeꢀ
Supportingꢀ Information).ꢀ Asꢀ weꢀ previouslyꢀ reportedꢀ theꢀ
regioselectiveꢀ alkenylationꢀ ofꢀ pyridineꢀ byꢀ cooperativeꢀ nickel/Lewisꢀ
Theꢀ regioselectiveꢀ alkenylationꢀ ofꢀ indolesꢀ isꢀ importantꢀ asꢀ
alkenylindoles ꢀ representꢀ usefulꢀ intermediatesꢀ inꢀ theꢀ synthesisꢀ ofꢀ
1
9
acidꢀ catalysis, ꢀ weꢀ subsequentlyꢀ examinedꢀ theꢀ effectꢀ ofꢀ addingꢀ
Lewisꢀ acidsꢀ (Tableꢀ 1,ꢀ entriesꢀ 2–7).ꢀ Additionꢀ ofꢀ AlMe3ꢀ (100ꢀ mol%)ꢀ
1a,1b
substitutedꢀ carbazoles,
1a,1c
ꢀ
tetrahydrocarbazoles,
ꢀ
spiroindolones. ꢀ Alkenylindolesꢀ areꢀ oftenꢀ preparedꢀ byꢀ cross-
andꢀ
1d,1e
couplingꢀ reactionsꢀ usingꢀ halogenatedꢀ indolesꢀ andꢀ organometallicꢀ
alkenylꢀ reagents, ꢀ orꢀ byꢀ theꢀ Wittigꢀ reactionꢀ ofꢀ theꢀ correspondingꢀ
2
Tableꢀ 1ꢀ ꢀ Optimisationꢀ ofꢀ theꢀ reactionꢀ conditionsꢀ forꢀ C3-selectiveꢀ alkenylationꢀ ofꢀ
indolesꢀwithꢀunactivatedꢀinternalꢀalkynes.ꢀ
3
acylindoles. ꢀ However,ꢀ theseꢀ conventionalꢀ strategiesꢀ oftenꢀ sufferꢀ
H
fromꢀ laboriousꢀ syntheses,ꢀ wherebyꢀ everyꢀ stepꢀ usuallyꢀ producesꢀ
stoichiometricꢀ amountsꢀ ofꢀ waste.ꢀ Inꢀ contrast,ꢀ transitionꢀ metal-
catalysedꢀ directꢀ C–Hꢀ alkenylationꢀ ofꢀ indolesꢀ withꢀ alkenesꢀ andꢀ
alkynesꢀ areꢀ attractiveꢀ becauseꢀ ofꢀ theirꢀ highꢀ step-ꢀ andꢀ atom-
efficiencyꢀ asꢀ wellꢀ asꢀ readyꢀ availabilityꢀ ofꢀ alkenesꢀ andꢀ alkynes.ꢀ
Accordingly,ꢀ severalꢀ studiesꢀ onꢀ C2-selectiveꢀ alkenylationꢀ withꢀ
H
N
R
Ni(cod)
ligand (10 mol%)
Lewis acid (100 mol%)
2
(10 mol%)
Pr
Pr
H
1
a (0.25 mmol)
H
Pr
+
+
Pr
Pr
toluene (0.83 mL)
N
R
Pr
N
R
8
0 °C, 2 h
2
a (0.75 mmol)
3aa
4aa
4
alkenesꢀandꢀalkynesꢀhaveꢀbeenꢀinvestigatedꢀbyꢀmetalꢀcatalysis. ꢀInꢀ
O
O
mostꢀ ofꢀ theseꢀ reactions,ꢀ indolesꢀ carryingꢀ anꢀ N-directingꢀ groupꢀ
affordꢀ 2-alkenylindolesꢀ inꢀ highꢀ yieldꢀ andꢀ regioselectivityꢀ throughꢀ
directedꢀ metalationꢀ atꢀ theꢀ C2-position.ꢀ C7-ꢀ andꢀ C4-selectiveꢀ
alkenylationsꢀ withꢀ enonesꢀ haveꢀ alsoꢀ beenꢀ developedꢀ withꢀ indolesꢀ
Al
MAD
ꢀ
a
Entryꢀ
Lewisꢀacidꢀ
Noneꢀ
Ligandꢀ
Rꢀ
Yieldꢀ3aa+4aa ꢀ
5
a
(
3aa/4aa) ꢀ
bearingꢀN-ꢀandꢀC3-directingꢀgroups. ꢀForꢀC3-selectiveꢀalkenylation,ꢀ
palladium-catalyzedꢀ oxidativeꢀ Heck-typeꢀ reactionsꢀ withꢀ enonesꢀ
haveꢀ beenꢀ developed. Theꢀ Friedel–Crafts-typeꢀ alkenylationꢀ ofꢀ
i
1ꢀ
2ꢀ
P Pr
3
3
3
3
3
3
3
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
C(O)Phꢀ(1a)ꢀ
C(O)Phꢀ
C(O)Phꢀ
C(O)Phꢀ
C(O)Phꢀ
C(O)Phꢀ
C(O)Phꢀ
C(O)Phꢀ
C(O)Phꢀ
C(O)Meꢀ
C(O)Cyꢀ
C(O)Phꢀ
Meꢀ(1a’)ꢀ
8%ꢀ(58:42)ꢀ
9%ꢀ(94:6)ꢀ
17%ꢀ(93:7)ꢀ
94%ꢀ(99:1)ꢀ
6ꢀ
i
AlMe
Al(C
MADꢀ
3
ꢀ
P Pr
7ꢀ
8
i
indolesꢀ withꢀ electrophiles includingꢀ alkynes ꢀ alsoꢀ givesꢀ 3-
alkenylindolesꢀselectively.ꢀHowever,ꢀtheꢀscopeꢀofꢀalkynesꢀhasꢀbeenꢀ
limitedꢀ toꢀ electron-deficientꢀ onesꢀ bearingꢀ carbonylꢀ and/orꢀ arylꢀ
groups.ꢀMoreover,ꢀtheyꢀsometimesꢀgiveꢀaꢀmixtureꢀofꢀE/Zꢀisomers.ꢀ
Herein,ꢀ weꢀ reportꢀ theꢀ C3-selectiveꢀ alkenylationꢀ ofꢀ indolesꢀ withꢀ
unactivatedꢀ internalꢀ alkynesꢀ byꢀ cooperativeꢀ nickel/aluminiumꢀ
catalysis.ꢀ Weꢀ achievedꢀ theꢀ highlyꢀ regio-ꢀ andꢀ stereoselectiveꢀ
transformationꢀ withꢀ theꢀ alkynesꢀ thatꢀ haveꢀ notꢀ beenꢀ suitableꢀ
3ꢀ
8
H
17
)
3
ꢀ
P Pr
i
4ꢀ
P Pr
b
i
c
5ꢀ
MAD ꢀ
B(C
ZnEt
P Pr
84%ꢀ(93:7) ꢀ
i
6ꢀ
6
F
5
)
3
ꢀ
P Pr
<5%ꢀ
<5%ꢀ
<5%ꢀ
<5%ꢀ
i
7ꢀ
2
ꢀ
P Pr
n
8ꢀ
MADꢀ
MADꢀ
P Pr
3
ꢀ
t
9ꢀ
3
P Bu ꢀ
b
i
c
10ꢀ
MAD ꢀ
P Pr
3
ꢀ
29%ꢀ(86:14) ꢀ
b
i
c
1
1
1
1ꢀ
2ꢀ
3ꢀ
MAD ꢀ
P Pr
3
3
3
ꢀ
ꢀ
ꢀ
56%ꢀ(88:12) ꢀ
b
i
c
MAD ꢀ
P Pr
27%ꢀ(>99:1) ꢀ
b
i
d
MAD ꢀ
P Pr
32%ꢀ(>99:1) ꢀ
a
DeterminedꢀbyꢀGCꢀanalysisꢀofꢀtheꢀcrudeꢀreactionꢀmixtureꢀGCꢀyieldsꢀincludingꢀ
b
c
isomersꢀ areꢀ givenꢀ inꢀ thisꢀ table.ꢀ 20ꢀ mol%ꢀ ofꢀ MADꢀ wereꢀ used.ꢀ NMRꢀ yield.ꢀ
d
Isolatedꢀyieldꢀwithꢀaꢀ1.0ꢀmmolꢀscale.ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ1ꢀꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

Pleaseꢀd Co hꢀ ne omt ꢀ Ca do j mu smt ꢀmarginsꢀ
Page 2 of 4
COMMUNICATIONꢀ
JournalꢀNameꢀ
improvedꢀtheꢀC3ꢀselectivityꢀ(3aa:4aaꢀ=ꢀ94:6),ꢀalbeitꢀinꢀpoorꢀoverallꢀ inꢀ goodꢀ yields.ꢀ Functionalꢀ groupsꢀ suchꢀ asꢀ aminoꢀ aVniedwꢀ pAritnicalecOonlalinteeꢀ
yieldꢀ (entryꢀ 2).ꢀ Comparableꢀ yieldꢀ andꢀ regioselectivityꢀ wasꢀ alsoꢀ borylꢀ moietiesꢀ remainedꢀ unaffectedꢀ und De Or ꢀI:r 1e 0a . 1c 0t i3o9 n/ Cꢀ 7c Co Cn 0d 0i t 8i o5 2n Js ꢀ
observedꢀwithꢀAl(C8H17)3ꢀ(entryꢀ3),ꢀwhileꢀmethylaluminiumꢀbis(2,6- involvingꢀstrongꢀLewisꢀacids,ꢀwhereasꢀotherꢀfunctionalitiesꢀsuchꢀasꢀ
1
0
di-tert-butyl-4-methylphenoxide)ꢀ (MAD) ꢀ dramaticallyꢀ improvedꢀ chloro,ꢀ alkoxycarbonyl,ꢀ andꢀ nitroꢀ groupsꢀ wereꢀ mostꢀ likelyꢀ notꢀ
theꢀ yieldꢀ (94%)ꢀ andꢀ regioselectivityꢀ (3aa:4aaꢀ =ꢀ 99:1)ꢀ (entryꢀ 4).ꢀ Aꢀ tolerated,ꢀ resultingꢀ inꢀ lowꢀ conversions.ꢀ 5-Cyanoindoleꢀ wasꢀ
1
1
catalyticꢀamountꢀofꢀMADꢀ(20ꢀmol%)ꢀstillꢀgaveꢀ3aaꢀinꢀhighꢀyieldꢀ(entryꢀ susceptibleꢀ toꢀ anꢀ alkyne-arylcyanationꢀ reaction. ꢀ Substituentsꢀ atꢀ
),ꢀ whileꢀ otherꢀ Lewisꢀ acidsꢀ suchꢀ asꢀ B(C6F5)3ꢀ andꢀ ZnEt2ꢀ wereꢀ notꢀ theꢀC4ꢀandꢀC2ꢀpositionꢀdidꢀnotꢀinterfereꢀwithꢀtheꢀC3ꢀselectivityꢀofꢀ
5
n
t
effectiveꢀ(entriesꢀ6ꢀandꢀ7).ꢀOtherꢀphosphinesꢀsuchꢀasꢀP Pr3ꢀandꢀP Bu3ꢀ thisꢀalkenylationꢀandꢀaffordedꢀ3eaꢀandꢀ3faꢀinꢀhighꢀyield.ꢀStericallyꢀ
didꢀnotꢀpromoteꢀthisꢀreaction,ꢀevenꢀinꢀtheꢀpresenceꢀofꢀMADꢀ(entriesꢀ biasedꢀ unsymmetricalꢀ internalꢀ alkynesꢀ couldꢀ alsoꢀ beꢀ convertedꢀ inꢀ
8ꢀandꢀ9).ꢀTheꢀN-acylꢀgroupꢀthatꢀwouldꢀcoordinateꢀtoꢀMADꢀwasꢀfoundꢀ thisꢀhydroheteroarylationꢀtoꢀaffordꢀadductsꢀ(3abꢀandꢀ3ac),ꢀinꢀwhichꢀ
toꢀ beꢀ crucialꢀ toꢀ controlꢀ theꢀ regioselectivityꢀ andꢀ yieldꢀ (entryꢀ 5ꢀ vs.ꢀ theꢀindolylꢀgroupꢀwasꢀintroducedꢀselectivelyꢀtransꢀwithꢀ respectꢀ toꢀ
entriesꢀ10–12).ꢀBetterꢀregioselectivityꢀwasꢀobservedꢀwithꢀstericallyꢀ theꢀ bulkyꢀ alkyneꢀ substituent.ꢀ Inꢀ theꢀ reactionꢀ withꢀ 1-
Tol 12
bulkierꢀN-substituents,ꢀalthoughꢀalkanoylꢀgroupsꢀgenerallyꢀaffordedꢀ trimethylsilylpropyneꢀ (2d),ꢀ NHCꢀ ligandꢀ IPr* , ꢀ was ableꢀ toꢀ
i
merelyꢀmodestꢀyields.ꢀTheꢀbenzoylꢀgroupꢀwasꢀconsideredꢀtoꢀbeꢀtheꢀ successfullyꢀ replaceꢀ PPr3ꢀ ꢀ atꢀ 50ꢀ °C,ꢀ whileꢀ 1,3-bis(2,6-
bestꢀ inꢀ termsꢀ ofꢀ yieldꢀ andꢀ regioselectivity.ꢀ N-Boc-indoleꢀ diisopropylphenyl)imidazol-2-ylideneꢀ(IPr)ꢀgaveꢀlessꢀthanꢀ5%ꢀofꢀ3ad.ꢀ
decomposedꢀ underꢀtheseꢀ reactionꢀ conditionsꢀ andꢀ gaveꢀ aꢀcomplexꢀ Aryl-substitutedꢀ alkynes,ꢀ enynes,ꢀ andꢀ terminalꢀ alkynesꢀ didꢀ notꢀ
mixture.ꢀWhenꢀN-methylindoleꢀ(1a’)ꢀwasꢀusedꢀunderꢀtheseꢀreactionꢀ affordꢀtheꢀproductsꢀdueꢀtoꢀrapidꢀoligomerization.ꢀTheꢀuseꢀofꢀanotherꢀ
Me2N
13
conditions,ꢀ theꢀ alkenylationꢀ proceededꢀ atꢀ theꢀ mostꢀ acidicꢀ C(2)–Hꢀ NHCꢀ ligand,ꢀ
bondꢀtoꢀgiveꢀ2-alkenylindoleꢀ4aa’ꢀwasꢀ obtainedꢀ selectivelyꢀ inꢀ 32%ꢀ property,ꢀ allowedꢀ theꢀ C3-selectiveꢀ alkylation ꢀ ofꢀ 1aꢀ withꢀ
yieldꢀ(entryꢀ13). vinylsilaneꢀ5ꢀtoꢀ3-silylethylindoneꢀ6ꢀwithꢀexclusiveꢀlinearꢀselectivityꢀ
Underꢀtheꢀ optimisedꢀ reactionꢀ conditions,ꢀ variousꢀ indolesꢀ (1a– (eqnꢀ(1)).ꢀ Thisꢀresultꢀ isꢀconsistentꢀwithꢀ ourꢀ previousꢀ findingsꢀthatꢀ
IPr, ꢀ thatꢀ wouldꢀ haveꢀ aꢀ strongerꢀ σ-donatingꢀ
14,15
ꢀ
2
1f)ꢀ andꢀ internalꢀ alkynesꢀ (2a–2d)ꢀ wereꢀ examinedꢀ (Tableꢀ 2).ꢀ Theꢀ NHCꢀ ligandsꢀ areꢀ effectiveꢀ toꢀ promoteꢀ theꢀ alkylationꢀ ofꢀ C(sp )–Hꢀ
alkenylationꢀ ofꢀ 1aꢀ withꢀ 2aꢀ withꢀ aꢀ 1.0ꢀ mmol-scaleꢀ successfullyꢀ bondsꢀofꢀ(hetero)arenesꢀbyꢀnickelꢀcatalysis.
9
b,14,16
ꢀꢀPhosphineꢀligandsꢀ
proceededꢀ toꢀ affordꢀ 3aaꢀ inꢀ 68%.ꢀ Theꢀ reactionꢀ couldꢀ alsoꢀ beꢀ didꢀ notꢀ affordꢀ anyꢀ alkylationꢀ productsꢀ asꢀ wasꢀ theꢀ caseꢀ withꢀ theꢀ
performedꢀ onꢀ aꢀ gram-scaleꢀ toꢀ giveꢀ 3aaꢀ inꢀ 51%ꢀ yield.ꢀ Allꢀ N- previousꢀstudies.ꢀNoꢀalkylationꢀtookꢀplaceꢀinꢀtheꢀabsenceꢀofꢀMAD,ꢀ
benzoylindolesꢀ substitutedꢀ atꢀ theꢀ C5ꢀ positionꢀ (1b–d)ꢀ wereꢀ indicatingꢀtheꢀimportanceꢀofꢀtheꢀaccelerationꢀbyꢀMAD.ꢀAlthoughꢀweꢀ
convertedꢀintoꢀtheꢀcorrespondingꢀalkenylindolesꢀ(3ba,ꢀ3ca,ꢀandꢀ3da)ꢀ alsoꢀexaminedꢀotherꢀ1-alkenesꢀsuchꢀasꢀ1-octeneꢀandꢀstyrene,ꢀtheseꢀ
atemptsꢀ affordedꢀ traceꢀ amountsꢀ ofꢀ theꢀ correspondingꢀ 3-
alkylindoles.ꢀ Moreover,ꢀ N-acylpyrroleꢀ (7)ꢀ alsoꢀ underwentꢀ theꢀ C3ꢀ
alkenylationꢀwithꢀ2aꢀunderꢀtheꢀoriginalꢀreactionꢀconditionsꢀtoꢀgiveꢀaꢀ
mixtureꢀ ofꢀ C3-mono-ꢀ (8)ꢀ andꢀ C3,4-dialkenylationꢀ (9)ꢀ productsꢀ inꢀ
Tableꢀ2ꢀꢀScopeꢀofꢀsubstrates.ꢀ
Ni(cod)
2
(10 mol%)
R3
i
R2
H
P Pr (10 mol%)
3
MAD (100 mol%)
17ꢀ
H
R1
+
R2
R3
modestꢀyieldꢀ(eqnꢀ(2)). ModificationꢀofꢀtheꢀN-substituentꢀfromꢀtheꢀ
H
R1
toluene (3.3 mL)
80 °C, 6 h
N
Bz
benzoylꢀ toꢀ adamantanoylꢀ groupꢀ wasꢀ necessaryꢀ toꢀ renderꢀ theꢀ
pyrroleꢀ substrateꢀ kineticallyꢀ moreꢀ stableꢀ underꢀ theꢀ reactionꢀ
conditionsꢀ employingꢀ theꢀ strongꢀ Lewisꢀ acidꢀ asꢀ N-benzoylpyrroleꢀ
decomposedꢀunderꢀtheseꢀstandardꢀreactionꢀconditions.ꢀꢀ
N
Bz
1
a–1f
2a–2d
3.0 mmol
1
.0 mmol
3aa–3ad
isolated yield (%)
+ isomers (3/isomers)a
3
ꢀ
Pr
Pr
Pr
Pr
Pr
Pr
Si
Ni(cod)2 (5.0 mol%)
Me2N
IPr (5.0 mol%)
H
H
H
H
MeO
N
MAD (100 mol%)
H
(1)
+
Si
H
N
Bz
N
Bz
N
Bz
toluene (3.3 mL)
80 °C, 9 h
N
Bz
N
Bz
3
aab
8% (96:4)
1% (96:4)c
Pr
3bab
3cad
1a
1.0 mmol
5
6
3%
6
5
78% (94:6)
80% (97:3)
3
.0 mmol
Si = SiMe(OSiMe3)2
6
ꢀ
ꢀ
Pr
Pr
Pr
Pr
Pr
Pr
Pr
Ni(cod)
2
(10 mol%)
Pr
Pr
H
MeO
i
Pr
H
P Pr (10 mol%)
3
H
H
H
H
H
Pr
H
(pin)B
MAD (100 mol%)
+
Pr
Pr
+
(2)
Me
N
H
toluene (3.3 mL)
60 °C, 48 h
N
N
N
Bz
N
Bz
N
Bz
O
Ad
O
O
3
da
3ea
3fa
Ad
Ad
7
6% (97:3)
83% (96:4)
75% (95:5)
7
2a
6.0 mmol
8
27%
9
13%
1
.0 mmol
TMS
Me
Aꢀ plausibleꢀ catalyticꢀ cycleꢀ forꢀ theꢀ C3-selectiveꢀ alkenylationꢀ isꢀ
Me
Me
H
H
H
proposedꢀinꢀSchemeꢀ1.ꢀInitially,ꢀtheꢀcarbonylꢀmoietyꢀofꢀtheꢀindoleꢀ
substrateꢀshouldꢀcoordinateꢀtoꢀMADꢀtoꢀformꢀadductꢀA,ꢀwhileꢀligandꢀ
exchangeꢀ betweenꢀ Ni(cod)2,ꢀ ligands,ꢀ andꢀ alkynesꢀ wouldꢀ provide
18,19ꢀ
N
N
N
Bz
Bz
Bz
3
ab
3ac
91% (>99:1)
3ade
<5% (—)
Tol 72% (87:13)
5
7% (81:19)
w/ IPr
w/ IPr*
nickel(0)ꢀcomplexꢀB.
i
Theꢀbulkierꢀandꢀelectron-donatingꢀligandsꢀ
suchꢀ asꢀ PPr3ꢀ andꢀ NHCꢀ ligandsꢀ wouldꢀ beꢀ importantꢀ toꢀ generateꢀ
ꢀ
a
TheꢀproductꢀmixturesꢀwereꢀconsistedꢀmainlyꢀofꢀtheꢀC2-substitutedꢀisomer,ꢀbutꢀ coordinativelyꢀ unsaturatedꢀ mono-ligatedꢀ andꢀ electron-richꢀ
2
otherꢀ isomersꢀ wereꢀ alsoꢀ detected.ꢀ Isolatedꢀ yieldsꢀ ofꢀ mixturesꢀ ofꢀ isomersꢀ areꢀ intermediateꢀB.ꢀη -Indole–nickelꢀcomplexꢀCꢀand,ꢀsubsequently,ꢀσ-
given.ꢀ 20ꢀmol%ꢀofꢀMADꢀwereꢀused.ꢀ 1aꢀ(1.5ꢀg,ꢀ6.8ꢀmmol)ꢀandꢀ2aꢀ(1.7ꢀg,ꢀ16ꢀmmol)ꢀ
b
c
complexꢀ Dꢀ wouldꢀ beꢀ formed.ꢀ Dꢀ shouldꢀ thenꢀ undergoꢀ ligand-to-
19
ligandꢀ hydrogenꢀ transferꢀ (LLHT) ꢀ processꢀ toꢀ constructꢀ C–C,ꢀ C–H,ꢀ
d
e
*Tol
wereꢀused.ꢀ Theꢀreactionꢀwasꢀcarriedꢀoutꢀonꢀaꢀ0.50ꢀmmolꢀscaleꢀforꢀ24ꢀh.ꢀ IPr
ꢀ
i
3
wasꢀusedꢀinsteadꢀofꢀP Pr ꢀatꢀ50ꢀ°C.ꢀ
2
ꢀ|ꢀJ.ꢀName.,ꢀ2012,ꢀ00,ꢀ1-3ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

Page 3 of 4
Pleaseꢀd Co hꢀ ne omt ꢀ Ca do j mu smt ꢀmarginsꢀ
JournalꢀNameꢀ
ꢀCOMMUNICATIONꢀ
R1
1 a)ꢀ B.ꢀ Sarojaꢀ andꢀ P.ꢀ C.ꢀ Srinvasan,ꢀ Synthesisꢀ1986,ꢀV7ie4w8A;ꢀrtbic)leꢀ EO.nꢀlMine.ꢀ
Beccalli,ꢀA.ꢀMarchesiniꢀandꢀT.ꢀPilati,ꢀTetra 2, ;ꢀ
Al
3
1
R1
he d: 1r o0 .n ꢀ19 9/ C6 ,ꢀ5 ꢀ3029
DOI 1039 7CC00852J
O
N
Al
c)ꢀC.ꢀGioia,ꢀA.ꢀHauville,ꢀL.ꢀBernardi,ꢀF.ꢀFiniꢀandꢀA.ꢀRicci,ꢀAngew.ꢀ
Chem.,ꢀInt.ꢀEd.ꢀ2008,ꢀ47,ꢀ9236;ꢀd)ꢀB.ꢀTan,ꢀG.ꢀH.ꢀTorresꢀandꢀC.ꢀF.ꢀ
Barbas,ꢀIII,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.ꢀ2011,ꢀ133,ꢀ12354;ꢀe)ꢀH.ꢀZheng,ꢀX.ꢀ
Liu,ꢀC.ꢀXu,ꢀY.ꢀXia,ꢀL.ꢀLinꢀandꢀX.ꢀFeng,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.ꢀ2015,ꢀ
Al
O
N
H
R2
R3
H
F
A
54,ꢀ10958.ꢀ
L
2
a)ꢀW.ꢀC.ꢀFrank,ꢀY.ꢀC.ꢀKimꢀandꢀR.ꢀF.ꢀHeck,ꢀJ.ꢀOrg.ꢀChem.ꢀ1978,ꢀ15,ꢀ
2947;ꢀb)ꢀQ.ꢀZheng,ꢀY.ꢀYangꢀandꢀA.ꢀR.ꢀMartin,ꢀTetrahedronꢀ Lett.ꢀ
1993,ꢀ 14,ꢀ 2235;ꢀ c)ꢀ P.ꢀ J.ꢀ Harringtonꢀ andꢀ L.ꢀ S.ꢀ Hegedus,ꢀ J.ꢀ Org.ꢀ
Chem.ꢀ1984,ꢀ49,ꢀ2657.ꢀ
Ni0
R3
R2
R3
R2
B
R1
R1
3 G.ꢀFridkin,ꢀN.ꢀBoutardꢀandꢀW.ꢀD.ꢀLubell,ꢀJ.ꢀOrg.ꢀChem.ꢀ2009,ꢀ74,ꢀ
5603;ꢀ b)ꢀ S.ꢀ V.ꢀ Ley,ꢀ S.ꢀ C.ꢀ Smith,ꢀ P.ꢀ R.ꢀ Woodward,ꢀ Tetrahedron,ꢀ
Al
Al
O
N
O
N
1992,ꢀ48,ꢀ1145;ꢀc)ꢀI.ꢀIwasaki,ꢀM.ꢀTerano,ꢀA.ꢀKurume,ꢀS.ꢀHara, M.ꢀ
H
Al = MAD
H
R3
i
, IPr*Tol, or Me2NIPr
L = P Pr
3
Ni0
YamashitaꢀandꢀS.ꢀOhta,ꢀTetrahedronꢀLett.ꢀ2005,ꢀ46,ꢀ6549;ꢀd)ꢀR.ꢀS.ꢀ
KusurkarꢀandꢀS.ꢀK.ꢀGoswami,ꢀTetrahedronꢀ2004,ꢀ60,ꢀ5315.ꢀ
NiII
R3
L
L
R2
R2
4 ForꢀC2-selectiveꢀalkenylationsꢀofꢀindoles,ꢀsee:ꢀa)ꢀA.ꢀG-Rubia,ꢀR.ꢀ
G.ꢀArrayásꢀandꢀJ.ꢀC.ꢀCarretero,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.ꢀ2009,ꢀ48,ꢀ
E
R1
C
6511;ꢀb)ꢀZ.ꢀDingꢀandꢀN.ꢀYoshikai,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.ꢀ2012,ꢀ
Al
O
N
51,ꢀ4698;ꢀc)ꢀA.ꢀKong,ꢀX.ꢀHanꢀandꢀX.ꢀLu,ꢀOrg.ꢀLett.ꢀ2006,ꢀ8,ꢀ1339;ꢀ
d)ꢀL.ꢀShi,ꢀX.ꢀZhong,ꢀH.ꢀShe,ꢀZ.ꢀLeiꢀandꢀF.ꢀLi,ꢀChem.ꢀCommun.ꢀ2015,ꢀ
51,ꢀ7136;ꢀe)ꢀL.ꢀLiang,ꢀS.ꢀFu,ꢀD.ꢀLin,ꢀX-Q.ꢀZhang,ꢀY.ꢀDeng,ꢀH.ꢀJiangꢀ
andꢀW.ꢀZeng,ꢀJ.ꢀOrg.ꢀChem.ꢀ2014,ꢀ79,ꢀ9472;ꢀf)ꢀD.ꢀJ.ꢀSchipper,ꢀM.ꢀ
HutchinsonꢀandꢀK.ꢀFagnou,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.ꢀ2010,ꢀ132,ꢀ6910;ꢀg)ꢀ
J.ꢀJia,ꢀJ.ꢀShi,ꢀJ.ꢀZhou,ꢀX.ꢀLiu,ꢀY.ꢀSong,ꢀH.ꢀE.ꢀXuꢀandꢀW.ꢀLi,ꢀChem.ꢀ
Commun.ꢀ 2015,ꢀ 51,ꢀ 2925;ꢀ h)ꢀ V.ꢀ Lankeꢀ andꢀ K.ꢀ R.ꢀ Prabhu,ꢀ Org.ꢀ
Lett.ꢀ 2013,ꢀ 15,ꢀ 2818;ꢀ i)ꢀ C.ꢀ Ferrer,ꢀ C.ꢀ H.ꢀ M.ꢀ Amijsꢀ andꢀ A.ꢀ M.ꢀ
Echavarren,ꢀChem.ꢀEur.ꢀJ.ꢀ2007,ꢀ13,ꢀ1358;ꢀj)ꢀC.ꢀFerrerꢀandꢀA.ꢀM.ꢀ
Echavarren,ꢀ Angew.ꢀ Chem.,ꢀ Int.ꢀ Ed.ꢀ2006,ꢀ45,ꢀ1105;ꢀ k)ꢀ B.ꢀ Li,ꢀJ.ꢀ
Ma,ꢀW.ꢀXie,ꢀH.ꢀSong,ꢀS.ꢀXuꢀandꢀB.ꢀWang,ꢀChem.ꢀEur.ꢀJ.ꢀ2013,ꢀ19,ꢀ
11863.ꢀ
H
R3
Ni0
L
R2
D
ꢀ
Schemeꢀ1ꢀꢀPlausibleꢀMechanismꢀ
andꢀ twoꢀ C–Niꢀ bondsꢀ inꢀ aꢀ concertedꢀ mannerꢀ andꢀ thusꢀ generateꢀ
alkenyl(indolyl)nickelꢀ complexꢀ E.ꢀWeꢀ cannotꢀ excludeꢀ aꢀ mechanismꢀ
involvingꢀstepwiseꢀformationꢀofꢀEꢀfromꢀDꢀviaꢀoxidativeꢀ additionꢀ ofꢀ
20ꢀ
5
ForꢀC4-ꢀandꢀC7-selectiveꢀalkenylationsꢀofꢀindoles,ꢀsee:ꢀa)ꢀJ.ꢀZhaoꢀ
andꢀ R.ꢀ C.ꢀ Larock,ꢀ J.ꢀ Org.ꢀ Chem.ꢀ 2006,ꢀ 71,ꢀ 5340;ꢀ b)ꢀ M.ꢀ F.ꢀ
Semmelhack,ꢀ P.ꢀ Knochelꢀ andꢀ T.ꢀ Singleton,ꢀ Tetrahedronꢀ Lett.ꢀ
theꢀ C(3)–Hꢀ followedꢀ byꢀ hydronickelationꢀ acrossꢀ alkynes. Theꢀ
reductiveꢀ eliminationꢀ ofꢀ 3–MADꢀ adductꢀ Fꢀ shouldꢀ proceedꢀ toꢀ
regenerateꢀBꢀuponꢀcoordinationꢀofꢀanꢀunreactedꢀalkyneꢀtoꢀtheꢀnickelꢀ
centre.ꢀ Theꢀ observedꢀ regioselectivityꢀ forꢀ unsymmetricalꢀ alkynesꢀ
couldꢀ beꢀ explainedꢀ byꢀ theirꢀ coordinationꢀ toꢀ theꢀ nickelꢀ centreꢀinꢀaꢀ
wayꢀ thatꢀ minimisesꢀ stericꢀ repulsionꢀ betweenꢀ theꢀ relativelyꢀ bulkyꢀ
alkyneꢀ substituentꢀ andꢀ theꢀ ligandsꢀ onꢀ theꢀ nickelꢀ centre.ꢀ Theꢀ
coordinationꢀtoꢀtheꢀLewisꢀacidꢀshouldꢀdecreaseꢀtheꢀelectronꢀdensityꢀ
ofꢀ theꢀ indoleꢀ coreꢀ toꢀ enhanceꢀ theꢀ reactivityꢀ ofꢀ theꢀ C(3)–Hꢀ bond,ꢀ
whileꢀ itsꢀ bulkinessꢀ wouldꢀ causeꢀ stericꢀ repulsionꢀ withꢀ theꢀ N-
substituentꢀtoꢀinduceꢀtheꢀobservedꢀhighꢀC3ꢀselectivityꢀatꢀtheꢀLLHTꢀ
step.ꢀ C3-selectiveꢀ alkylationꢀ ofꢀ 1aꢀ wouldꢀ proceedꢀ inꢀ aꢀ similarꢀ
manner,ꢀ inꢀ whichꢀ stericꢀ repulsionꢀ betweenꢀ theꢀ bulkyꢀ silylꢀ
substituentꢀ andꢀ theꢀ ligandꢀ onꢀ nickelꢀ accountsꢀ forꢀ theꢀ linearꢀ
selectivity.ꢀꢀ
1993,ꢀ34,ꢀ5051;ꢀc)ꢀV.ꢀLankeꢀandꢀK.ꢀR.ꢀPrabhu,ꢀOrg.ꢀLett.ꢀ2013,ꢀ15,ꢀ
6262;ꢀd)ꢀV.ꢀLanke,ꢀK.ꢀR.ꢀBettadapurꢀandꢀK.ꢀR.ꢀPrabhu,ꢀOrg.ꢀLett.ꢀ
2016,ꢀ18,ꢀ5496.ꢀe)ꢀN.ꢀK.ꢀMishra,ꢀT.ꢀJeong,ꢀS.ꢀSharma,ꢀY.ꢀShin,ꢀS.ꢀ
Han,ꢀJ.ꢀPark,ꢀJ.ꢀS.ꢀOh,ꢀJ.ꢀH.ꢀKwark,ꢀY.ꢀH.ꢀJungꢀandꢀI.ꢀS.ꢀKim,ꢀAdv.ꢀ
Synth.ꢀCatal.ꢀ2015,ꢀ357,ꢀ1293;ꢀf)ꢀS.ꢀPan,ꢀT.ꢀWakaki,ꢀN.ꢀRyuꢀandꢀT.ꢀ
Shibata,ꢀ Chem.ꢀ Asianꢀ J.ꢀ 2014,ꢀ 9,ꢀ 1257;ꢀ g)ꢀ J.ꢀ Winkelblech,ꢀ M.ꢀ
Liebhold,ꢀJ.ꢀGunera,ꢀX.ꢀXie,ꢀP.ꢀKolbꢀandꢀS-M.ꢀLi,ꢀAdv.ꢀSynth.ꢀCatal.ꢀ
2015,ꢀ357,ꢀ975.ꢀ
6
ForꢀC3-selectiveꢀoxidativeꢀalkenylationsꢀofꢀindolesꢀwithꢀalkenes,ꢀ
see:ꢀ a)ꢀ T.ꢀ Itahara,ꢀ M.ꢀ Ikedaꢀ andꢀ T.ꢀ Sakakibara,ꢀ J.ꢀ Chem.ꢀ Soc.ꢀ
PerkinꢀTrans.ꢀ1983,ꢀ1361;ꢀb)ꢀE.ꢀCapito,ꢀJ.ꢀM.ꢀBrownꢀandꢀA.ꢀRicci,ꢀ
Chem.ꢀCommun.ꢀ2005,ꢀ1854;ꢀc)ꢀN.ꢀP.ꢀGrimster,ꢀC.ꢀGauntlett,ꢀC.ꢀR.ꢀ
A.ꢀGodfleyandꢀandꢀM.ꢀJ.ꢀGaunt,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.ꢀ2005,ꢀ44,ꢀ
3125;ꢀ d)ꢀ A.ꢀ Maehara,ꢀ H.ꢀ Tsurugi,ꢀ T.ꢀ Satohꢀ andꢀ M.ꢀ Miura,ꢀ Org.ꢀ
Lett.ꢀ2008,ꢀ10,ꢀ1159;ꢀS.ꢀSahu,ꢀA.ꢀBanerjeeꢀandꢀM.ꢀS.ꢀMaji,ꢀOrg.ꢀ
Lett.ꢀ2017,ꢀdoi:ꢀ10.1021/acs.orglett.6b03612ꢀ
ForꢀC3-selectiveꢀalkenylationꢀofꢀindolesꢀwithꢀ1,3-diketones,ꢀsee:ꢀ
A.ꢀArcadi,ꢀM.ꢀAlfonsi,ꢀG.ꢀBianchi,ꢀG.ꢀD ’A nniballeꢀandꢀF.ꢀMarinelli,ꢀ
Adv.ꢀSynth.ꢀCatal.ꢀ2006,ꢀ348,ꢀ331.ꢀ
ForꢀC3-selectiveꢀalkenylationsꢀofꢀindolesꢀwithꢀalkynes,ꢀsee:ꢀa)ꢀW.ꢀ
Lu,ꢀC.ꢀJia,ꢀT.ꢀKitamuraꢀandꢀY.ꢀFujiwara,ꢀOrg.ꢀLett.ꢀ2000,ꢀ2,ꢀ2927;ꢀb)ꢀ
G.ꢀ Bhaskar,ꢀ C.ꢀ Sailumar,ꢀ P.ꢀ T.ꢀ Perumal,ꢀ Tetrahedronꢀ Lett.ꢀ2010,ꢀ
Inꢀ summary,ꢀ cooperativeꢀ nickel/aluminiumꢀ catalysisꢀ isꢀ
demonstratedꢀ toꢀ achieveꢀ theꢀ C3-selectiveꢀ alkenylationꢀ ofꢀ N-
acylindolesꢀ withꢀ unactivatedꢀ internalꢀ alkynes.ꢀ Inꢀ thisꢀ cooperativeꢀ
system,ꢀ aꢀ bulkyꢀ Lewisꢀ acidꢀ bothꢀ acceleratesꢀ theꢀ desiredꢀ
transformationꢀ andꢀ controlsꢀ theꢀ regioselectivityꢀ inꢀ collaborationꢀ
withꢀ theꢀ bulkyꢀ N-substituentꢀ ofꢀ theꢀ indoleꢀ substrates.ꢀ Furtherꢀ
effortsꢀwillꢀleadꢀtoꢀtheꢀcooperativeꢀcatalysisꢀforꢀtheꢀregioselectiveꢀC–
Hꢀfunctionalizationꢀofꢀotherwiseꢀunreactiveꢀ(hetero)arenes.
7
8
5
1,ꢀ3141;ꢀc)ꢀY.ꢀZhang,ꢀTetrahedronꢀ2006,ꢀ62,ꢀ3917.ꢀ
a)ꢀY.ꢀNakao,ꢀK.ꢀS.ꢀKanyivaꢀandꢀT.ꢀHiyama,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.ꢀ2008,ꢀ
30,ꢀ2448;ꢀb)ꢀY.ꢀNakao,ꢀY.ꢀYamada,ꢀN.ꢀKashiharaꢀandꢀT.ꢀHiyama,ꢀJ.ꢀ
Am.ꢀChem.ꢀSoc.ꢀ2010,ꢀ132,ꢀ13666.ꢀ
9
1
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀCRESTꢀprogramꢀ“Establishmentꢀ
ofꢀ Molecularꢀ Technologyꢀ towardsꢀ theꢀ Creationꢀ ofꢀ Newꢀ Functions”ꢀ 10 a)ꢀ K.ꢀ Maruoka,ꢀ T.ꢀ Itoh,ꢀ M.ꢀ Sakurai,ꢀ K.ꢀ Nonoshitaꢀ andꢀ H.ꢀ
Yamamoto,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.ꢀ1988,ꢀ110,ꢀ3588;ꢀb)ꢀM.ꢀB.ꢀPower,ꢀ
S.ꢀG.ꢀBott,ꢀJ.ꢀL.ꢀAtwoodꢀandꢀA.ꢀR.ꢀBarron,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.ꢀ1990,ꢀ
AreaꢀfromꢀJSTꢀandꢀbyꢀ"JSPSꢀKAKENHIꢀGrantꢀNumberꢀJP15H05799ꢀinꢀ
ꢀ
PreciselyꢀDesignedꢀCatalystsꢀwithꢀCustomizedꢀScaffolding".
112,ꢀ3446;ꢀc)ꢀS.ꢀSaitoꢀandꢀH.ꢀYamamoto,ꢀChem.ꢀCommun.ꢀ1997,ꢀ
1585.ꢀ
1
1
1 Y.ꢀNakao,ꢀBull.ꢀChem.ꢀSoc.ꢀJpn.ꢀ2012,ꢀ85,ꢀ731.ꢀ
2 A.ꢀCollado,ꢀA.ꢀG-Suárez,ꢀA.ꢀR.ꢀMartin,ꢀA.ꢀM.ꢀZ.ꢀSlawinꢀandꢀS.ꢀP.ꢀ
Nolan,ꢀChem.ꢀCommun.ꢀ2013,ꢀ49,ꢀ5541.ꢀ
Notesꢀandꢀreferencesꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ3ꢀ
Pleaseꢀdoꢀnotꢀadjustꢀmarginsꢀ

Pleaseꢀd Co hꢀ ne omt ꢀ Ca do j mu smt ꢀmarginsꢀ
Page 4 of 4
COMMUNICATIONꢀ
JournalꢀNameꢀ
1
1
3 Y.ꢀ Zhang,ꢀ V.ꢀCésar,ꢀG.ꢀStorch,ꢀN.ꢀLuganꢀandꢀG.ꢀLavigne,ꢀAngew.ꢀ
Chem.,ꢀInt.ꢀEd.ꢀ2014,ꢀ53,ꢀ6482.ꢀ
4 Forꢀ C2-selectiveꢀ alkylationꢀ ofꢀ indolesꢀ withꢀ olefins,ꢀ see:ꢀ Y.ꢀ
Schramm,ꢀM.ꢀTakeuchi,ꢀK.ꢀSemba,ꢀY.ꢀNakaoꢀandꢀJ.ꢀF.ꢀHartwig,ꢀJ.ꢀ
Am.ꢀChem.ꢀSoc.ꢀ2015,ꢀ137,ꢀ12215.ꢀ
View Article Online
DOI: 10.1039/C7CC00852J
1
5 ForꢀC3-selectiveꢀalkylationꢀofꢀindolesꢀwithꢀolefins,ꢀsee:ꢀa)ꢀA.ꢀV.ꢀ
Reddy,ꢀ K.ꢀ Ravinder,ꢀ T.ꢀ V.ꢀ Goud,ꢀ P.ꢀ Krishnaiah,ꢀ T.ꢀ V.ꢀ Rajuꢀ andꢀ Y.ꢀ
Venkateswarlu,ꢀTetrahedronꢀLett.ꢀ2003,ꢀ44,ꢀ6257;ꢀb)ꢀB.ꢀK.ꢀBanik,ꢀ
M.ꢀFernandezꢀandꢀC.ꢀAlavarez,ꢀTetrahedronꢀLett.ꢀ2005,ꢀ46,ꢀ2479;ꢀ
c)ꢀZ-H.ꢀHuang,ꢀJ-P.ꢀ Zouꢀ andꢀ W-Q.ꢀJiang,ꢀTetrahedronꢀ Lett.ꢀ2006,ꢀ
47,ꢀ7965;ꢀd)ꢀZ.ꢀLi,ꢀZ.ꢀShiꢀandꢀC.ꢀHe,ꢀJ.ꢀOrganomet.ꢀChem.ꢀ2005,ꢀ
690,ꢀ5049;ꢀe)ꢀZ.ꢀZhang,ꢀX.ꢀWangꢀandꢀR.ꢀA.ꢀWidenhoefer,ꢀChem.ꢀ
Commun.ꢀ2006,ꢀ3717.ꢀ
1
1
6 S.ꢀOkumura,ꢀS.ꢀTang,ꢀT.ꢀSaito,ꢀK.ꢀSemba,ꢀS.ꢀSakakiꢀandꢀY.ꢀNakao,ꢀJ.ꢀ
Am.ꢀChem.ꢀSoc.ꢀ2016,ꢀ44,ꢀ138.ꢀ
7 Forꢀtheꢀalkenylationꢀofꢀpyrroles,ꢀsee:ꢀa)ꢀN.ꢀTsukada,ꢀK.ꢀMurata,ꢀ
andꢀY.ꢀInoue,ꢀTetrahedronꢀ Lett.ꢀ2005,ꢀ46,ꢀ7515;ꢀb)ꢀJ.ꢀOyamadaꢀ
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