Hydrogen-bonding catalysis of sulfonium salts

Article abstract of DOI:10.1039/c6cc08411g

Although quaternary ammonium and phosphonium salts are known as important catalysts in phase-transfer catalysis, the catalytic ability of tertiary sulfonium salts has not yet been well demonstrated. Herein, we demonstrate the catalytic ability of trialkyl

Full text of DOI:10.1039/c6cc08411g

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Kumatabara, S. Shimizu, K. Maruoka and S. Shirakawa, Chem. Commun., 2016, DOI:
1
0.1039/C6CC08411G.
Volume 52 Number
1
4
January 2016 Pages 1–216
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ISSN 1359-7345
COMMUNICATION
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
rsc.li/chemcomm

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Pleaseꢀd Co hꢀ ne omt ꢀ Ca do j mu s mt ꢀmarginsꢀ
View Article Online
DOI: 10.1039/C6CC08411G
ChemCommꢀ
COMMUNICATIONꢀ
ꢀ
Hydrogen-bondingꢀcatalysisꢀofꢀsulfoniumꢀsaltsꢀ
a
a
b
c
a
ShihoꢀKaneko, ꢀYusukeꢀKumatabara, ꢀShoichiꢀShimizu, ꢀKeijiꢀMaruoka ꢀandꢀSeijiꢀShirakawa* ꢀ
Receivedꢀ00thꢀJanuaryꢀ20xx,ꢀ
Acceptedꢀ00thꢀJanuaryꢀ20xxꢀ
DOI:ꢀ10.1039/x0xx00000xꢀ
www.rsc.org/ꢀ
6
,7
Althoughꢀ quaternaryꢀ ammoniumꢀ andꢀ phosphoniumꢀ saltsꢀ areꢀ atomsꢀ(Fig.ꢀ2). ꢀHerein,ꢀweꢀdemonstrateꢀtheꢀcatalyticꢀabilityꢀ
8
ꢀ
knownꢀ asꢀ importantꢀ catalystsꢀ inꢀ phase-transferꢀ catalysis,ꢀ theꢀ ofꢀtrialkylsulfoniumꢀsaltsꢀinꢀhydrogen-bondingꢀcatalysis.
catalyticꢀabilityꢀofꢀtertiaryꢀsulfoniumꢀsaltsꢀhasꢀnotꢀyetꢀbeenꢀwellꢀ
demonstrated.ꢀ Herein,ꢀ weꢀ demonstrateꢀ theꢀ catalyticꢀ abilityꢀ ofꢀ
trialkylsulfoniumꢀsaltsꢀasꢀhydrogen-bondingꢀcatalystsꢀonꢀtheꢀbasisꢀ
ofꢀtheꢀcharacteristicꢀpropertiesꢀofꢀtheꢀacidicꢀαꢀhydrogenꢀatomsꢀonꢀ
alkylsulfoniumꢀsalts.ꢀ
R4N+ X–
R4P+ X–
R3S+ X–
ammonium salt phosphonium salt
sulfonium salt
Hofmann
Corey-Chaykovsky
reaction
reagents
catalysts
Wittig reaction
elimination
Theꢀ importanceꢀ ofꢀ oniumꢀ saltꢀ compoundsꢀ hasꢀ beenꢀ
1
establishedꢀinꢀtheꢀfieldꢀofꢀorganicꢀchemistry. ꢀAlkyl-ammonium,ꢀ
phase-transfer catalyst
Brønsted and Lewis base catalysts
lack of examples
(this work)
phosphonium,ꢀ andꢀ sulfoniumꢀ saltsꢀ areꢀ someꢀ ofꢀ theꢀ mostꢀ
importantꢀandꢀreliableꢀoniumꢀsaltꢀreagentsꢀinꢀorganicꢀsynthesisꢀ
ꢀ
Fig.ꢀ1ꢀꢀOniumꢀsaltsꢀinꢀorganicꢀsynthesis.ꢀ
ꢀ
effectiveꢀ hydrogen-bondingꢀ catalysts, ꢀ weꢀ focusedꢀ onꢀ simpleꢀ
Basedꢀonꢀtheꢀdesignꢀofꢀtypeꢀ1ꢀtetraalkylammoniumꢀsaltsꢀasꢀ
6
(
Fig.ꢀ 1).ꢀ Theseꢀ compoundsꢀ areꢀ oftenꢀ utilizedꢀ asꢀ veryꢀ usefulꢀ
reagentsꢀinꢀtheꢀconstructionꢀofꢀorganicꢀbuildingꢀblocks,ꢀandꢀtheꢀ
reactionsꢀusingꢀtheseꢀreagentsꢀappearꢀinꢀtextbooksꢀofꢀorganicꢀ
typeꢀ2ꢀ trialkylsulfoniumꢀsaltsꢀ (Fig.ꢀ2).ꢀTheꢀstructuresꢀofꢀtheꢀαꢀ
hydrogenꢀ atomsꢀ thatꢀ bindedꢀ toꢀ theꢀ iodideꢀ anionꢀ comparedꢀ
favorablyꢀtoꢀtheꢀX-rayꢀcrystalꢀstructuresꢀofꢀammoniumꢀiodideꢀ
2
,3
chemistryꢀ asꢀ important,ꢀ namedꢀ reactions. ꢀ Furthermore,ꢀ
quaternaryꢀammoniumꢀandꢀphosphoniumꢀsaltsꢀareꢀalsoꢀknownꢀ
asꢀreliableꢀcatalysts,ꢀwhichꢀareꢀusedꢀtoꢀpromoteꢀaꢀwideꢀvarietyꢀ
ofꢀ organicꢀ transformationsꢀ asꢀ phase-transferꢀ and/orꢀ baseꢀ
9
,10
1
acidityꢀ ofꢀ theꢀ αꢀ hydrogenꢀ atomsꢀ ofꢀ 2aꢀ toꢀ approximateꢀ theꢀ
a
ꢀandꢀsulfoniumꢀiodideꢀ2a
.
ꢀFurthermore,ꢀweꢀexpectedꢀtheꢀ
1
1ꢀ
4
a
acidityꢀofꢀ1a,ꢀbasedꢀonꢀtheꢀreportedꢀpK ꢀvalues.
catalysts. ꢀ Despiteꢀ theꢀ wideꢀ syntheticꢀ utilityꢀ ofꢀ oniumꢀ saltꢀ
compoundsꢀ asꢀ reagentsꢀ andꢀ catalysts,ꢀ theꢀ catalyticꢀ abilityꢀ ofꢀ
tertiaryꢀsulfoniumꢀsaltsꢀhasꢀnotꢀyetꢀbeenꢀdemonstratedꢀwellꢀinꢀ
5
organicꢀ synthesis. ꢀ Theꢀ limitationꢀ ofꢀ sulfoniumꢀ saltꢀ catalystsꢀ
δ+
I
H
I
δ+
δ+
hasꢀbeenꢀattributedꢀmainlyꢀtoꢀtheꢀhighꢀreactivityꢀandꢀinstabilityꢀ
ofꢀ theꢀ compoundsꢀ withꢀ acidicꢀ αꢀ hydrogenꢀ atoms.ꢀ Toꢀ createꢀ
newꢀpossibilitiesꢀforꢀsulfoniumꢀsaltsꢀasꢀcatalysts,ꢀweꢀfocusedꢀonꢀ
theꢀ hydrogen-bondingꢀ abilitiesꢀ ofꢀ αꢀ hydrogenꢀ atomsꢀ onꢀ
H
H
Y
δ+
H
Hδ+
MeO C
2
N
2
CO Me
N
Y
δ+
1
a
CH3
(Y = CO2Me)
X-ray
alkylsulfoniumꢀ saltsꢀ whenꢀ weꢀ reportedꢀ theꢀ useꢀ ofꢀ typeꢀ 1ꢀ
tetraalkylammoniumꢀ saltsꢀ asꢀ hydrogen-bondingꢀ catalystsꢀ onꢀ
theꢀ basisꢀ ofꢀ theꢀ characteristicꢀ propertiesꢀ ofꢀ theꢀ αꢀ hydrogenꢀ
δ+
I
I
H
δ+
H
δ+
δ+
H
S
H
δ+
H
Hδ+
S
δ+
2
a
H
X-ray
CO2Et Me2S
Me3N
H
Me3N
Ph Me3N
Ph
H
H
H
H
H
H
H
H
pKa
in DMSO)
4
2.0
31.9
20.0
17.8
(
ꢀ
Fig.ꢀ 2ꢀ ꢀ Comparisonꢀ betweenꢀ ammoniumꢀ iodideꢀ 1aꢀ andꢀ
sulfoniumꢀiodideꢀ2a.ꢀ
ElectronicꢀSupplementaryꢀInformationꢀ(ESI)ꢀavailable:ꢀExperimentalꢀdetailsꢀandꢀ
characterizationꢀdataꢀforꢀnewꢀcompounds.ꢀSeeꢀDOI:ꢀ10.1039/x0xx00000xꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ1ꢀꢀ

Pleaseꢀd Co hꢀ ne omt ꢀ Ca do j mu s mt ꢀmarginsꢀ
Page 2 of 4
COMMUNICATIONꢀ
ChemCommꢀ
ꢀ
Withꢀ importantꢀ structuralꢀ informationꢀ ofꢀ theꢀ sulfoniumꢀ chlorideꢀ substratesꢀ ofꢀ typeꢀ
saltsꢀofꢀtypeꢀ ꢀinꢀhand,ꢀtheꢀcatalyticꢀabilityꢀofꢀ
bondingꢀcatalystsꢀwasꢀinvestigatedꢀinꢀaꢀMannich-typeꢀreactionꢀ
ofꢀ N-acylisoquinolineꢀ 5a,ꢀ whichꢀ wasꢀ generatedꢀ inꢀ situꢀ fromꢀ ofꢀtheꢀtitrationꢀofꢀ
,2,2-trichloroethylꢀchloroformateꢀ(TrocCl)ꢀandꢀisoquinoline,ꢀasꢀ 0.073ꢀppmꢀafterꢀaddingꢀ20ꢀequivꢀofꢀ
5
,ꢀ weꢀ performedꢀ NMRꢀ titrationꢀ
View Article Online
DOI: 10.1039/C6CC08411G
2
2ꢀasꢀaꢀhydrogen- studiesꢀofꢀbenzylsulfoniumꢀsaltꢀ4ꢀwithꢀchlorodiphenylmethaneꢀ
8
ꢀasꢀaꢀrelativelyꢀstableꢀchlorideꢀcompoundꢀ(Fig.ꢀ3).ꢀAsꢀaꢀresultꢀ
,ꢀtheꢀclearꢀupfieldꢀchemicalꢀshiftsꢀ(0.065–
)ꢀofꢀtheꢀαꢀhydrogenꢀatomsꢀ
ꢀ wereꢀ observedꢀ inꢀ Hꢀ NMRꢀ measurementsꢀ (0.010ꢀ Mꢀ inꢀ
reactionꢀofꢀ5aꢀwithꢀketeneꢀsilylꢀacetalꢀ6aꢀproceededꢀslowlyꢀinꢀ CDCl ).ꢀ Thisꢀ resultꢀ stronglyꢀ supportedꢀ theꢀ propositionꢀ thatꢀ
theꢀabsenceꢀofꢀaꢀcatalystꢀatꢀ–78ꢀ°Cꢀforꢀ3ꢀhꢀ(7%ꢀyield;ꢀentryꢀ1).ꢀ sulfoniumꢀsaltsꢀcouldꢀactivateꢀchlorideꢀsubstratesꢀofꢀtypeꢀ ꢀviaꢀ
Theꢀreactionꢀwithꢀammoniumꢀiodideꢀcatalystꢀ1aꢀwasꢀpromotedꢀ hydrogenꢀ bondingꢀ toꢀ promoteꢀ theꢀ Mannich-typeꢀ reaction.ꢀ Aꢀ
toꢀaꢀmoderateꢀextentꢀ(38%ꢀyield;ꢀentryꢀ2).ꢀSulfoniumꢀiodideꢀ2a titrationꢀ experimentꢀ withꢀ ammoniumꢀ saltꢀ 1bꢀ wasꢀ alsoꢀ
wasꢀthenꢀexaminedꢀasꢀaꢀcatalyst,ꢀandꢀaꢀmoderateꢀaccelerationꢀ performedꢀ withꢀ theꢀ sameꢀ concentrationꢀ (0.010ꢀ Mꢀ inꢀ CDCl ),ꢀ
ofꢀ theꢀ reactionꢀ wasꢀ alsoꢀ observedꢀ (30%ꢀ yield;ꢀ entryꢀ 3).ꢀ Itꢀ andꢀ theꢀ degreesꢀ ofꢀ chemicalꢀ shiftsꢀ (0.041–0.048ꢀ ppmꢀ afterꢀ
shouldꢀ beꢀ notedꢀ thatꢀ simpleꢀ ammoniumꢀ iodideꢀ catalystꢀ 3a addingꢀ20ꢀequivꢀofꢀ )ꢀwereꢀsmallerꢀthanꢀthoseꢀforꢀtheꢀtitrationꢀ
showedꢀalmostꢀnoꢀaccelerationꢀofꢀtheꢀreactionꢀ(9%ꢀyield;ꢀentryꢀ withꢀ4ꢀ(Fig.ꢀS2ꢀinꢀSupplementaryꢀInformation).ꢀ
8
2
8
1
2
6a
1
aꢀbenchmarkꢀreactionꢀ(Tableꢀ1). ꢀAsꢀpreviouslyꢀreported, ꢀtheꢀ ofꢀ
4
3
5
ꢀ
3
ꢀ
8
Ph
Ph
4
).ꢀTheseꢀresultsꢀclearlyꢀdemonstratedꢀtheꢀimportanceꢀofꢀtheꢀ
BArF
acidityꢀofꢀαꢀhydrogenꢀatomsꢀonꢀaꢀsulfoniumꢀsaltꢀ2aꢀtoꢀpromoteꢀ
theꢀ reaction.ꢀ Theꢀ exchangeꢀ ofꢀ theꢀ counteranionꢀ inꢀ 2aꢀ toꢀ
–
tetrakis[3,5-bis(trifluoromethyl)phenyl]borateꢀ (BArF )ꢀ asꢀ aꢀ
Cl
aH
a'H
Ha
Ha'
Ph
Ph
BArF
H
S
+
H
Cl
H
bH
bH
H
non-coordinatingꢀcounteranionꢀ(2b)ꢀimprovedꢀtheꢀresultsꢀ(47%ꢀ
Ph
S
Ph
4
8
yield,ꢀ entryꢀ 5).ꢀ Theꢀ reactionꢀ withꢀ benzylsulfoniumꢀ barfateꢀ
furtherꢀ improvedꢀ theꢀ results,ꢀ andꢀ theꢀ catalystꢀ ꢀ exhibitedꢀ aꢀ
somewhatꢀhigherꢀreactivityꢀthanꢀthatꢀofꢀammoniumꢀbarfateꢀ1bꢀ
67ꢀandꢀ61%ꢀyields,ꢀrespectively;ꢀentriesꢀ6ꢀvs.ꢀ7).ꢀ
Tableꢀ1.ꢀꢀEffectꢀofꢀcatalystsꢀinꢀtheꢀMannich-typeꢀreactionꢀofꢀN-
4ꢀ
Hb
H
H
Ha
–0.073
Ha'
4
4
+ 8 (20 equiv)
–
0.067 ppm
–0.065
(
4
4
4
+ 8 (15 equiv)
+ 8 (10 equiv)
+ 8 (7 equiv)
–
–
0.051 ppm
0.038 ppm
–0.055
–0.040
–0.031
–0.048
–0.035
–0.029
a
acylisoquinolineꢀ5a
ꢀ
catalyst
10 mol %)
OSiMe
3
(
N
N
+
Troc
OMe
Troc
Me
–0.029 ppm
THF
–78 °C, 3 h
Cl
5
a
6a
7a
CO
2
4
4
4
+ 8 (4 equiv)
+ 8 (1 equiv)
only
–
0.018 ppm
–0.020
–0.006
–0.018
–0.005
X
X
–0.006 ppm
N
O
+
MeO
2
C
N
CO
2
Me
S
Cl
O
CCl
3
4
.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.6
a : X– = I–
b : X– = BArF–
2a : X– = I–
2b : X– = BArF–
ppm
1
ꢀ
1
Fig.ꢀ3ꢀꢀ HꢀNMRꢀtitrationꢀstudyꢀofꢀ4.ꢀ
1
δ+ N
Troc
ꢀ
I
BArF
δ–
ꢀ
Benzylsulfoniumꢀ saltꢀ catalystꢀ 4ꢀ couldꢀ accelerateꢀ theꢀ
δ+ Cl
X
H
reactionꢀofꢀN-acylisoquinolineꢀ5aꢀwithꢀketone-derivedꢀsilylꢀenolꢀ
etherꢀ6bꢀtoꢀgiveꢀtheꢀcorrespondingꢀproductꢀ7bꢀinꢀaꢀmoderateꢀ
yieldꢀ (Schemeꢀ 1).ꢀ Theꢀ reactionꢀ withꢀ 3-methylisoquinolineꢀ
N
S
δ+
δ+
H
δ+
H
H
3
a
4
Ph
S
R
Hδ+
BArF– = [3,5-(CF
3
)
2
-C
6
H
3
]
4
B
derivativeꢀ 5bꢀ withꢀ 6aꢀ wasꢀ alsoꢀ acceleratedꢀ byꢀ catalystꢀ 4ꢀ toꢀ
δ+
H
ꢀ
b
obtainꢀ productꢀ 7cꢀ inꢀ aꢀ moderateꢀ yield.ꢀ Weꢀ alsoꢀ examinedꢀ
Entryꢀ
Catalystꢀ
nonecꢀ
Yield ꢀ(%)ꢀ
sulfoniumꢀ salt-catalyzedꢀ regioselectiveꢀ reactionsꢀ withꢀ
1
2
3
4
5
6
7
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
7ꢀ
1
3
1aꢀ
2aꢀ
3aꢀ
2bꢀ
4ꢀ
38ꢀ
30ꢀ
9ꢀ
47ꢀ
67ꢀ
61ꢀ
quinolinesꢀ
promotedꢀbyꢀcatalystꢀ
regioselectivityꢀ(10a 11aꢀ6:1).ꢀFurthermore,ꢀtheꢀreactionꢀwithꢀ
-chloroquinolineꢀ9bꢀgaveꢀproductꢀ10bꢀinꢀaꢀgoodꢀyieldꢀwithꢀanꢀ
almostꢀperfectꢀlevelꢀofꢀregioselectivityꢀ(10b 11bꢀ>30:1).ꢀ
Toꢀexpandꢀtheꢀutilityꢀofꢀsulfoniumꢀsaltꢀcatalysts,ꢀweꢀwereꢀ
9
. ꢀ Theꢀ reactionꢀ ofꢀ quinolineꢀ 9aꢀ wasꢀ efficientlyꢀ
4
ꢀtoꢀgiveꢀproductꢀ10aꢀinꢀaꢀgoodꢀyieldꢀandꢀ
/
6
/
1bꢀ
ꢀ
aReactionꢀ conditions:ꢀ 5aꢀ (0.20ꢀ mmol),ꢀ 6aꢀ (0.30ꢀ mmol),ꢀ
catalystꢀ(0.020ꢀmmol,ꢀ10ꢀmolꢀ%),ꢀTHFꢀ(4.0ꢀmL),ꢀ–78ꢀ°C,ꢀ3ꢀh.ꢀ
bYieldꢀ ofꢀ theꢀ isolatedꢀ productꢀ 7a.ꢀ Theꢀ reactionꢀ wasꢀ
performedꢀwithoutꢀaꢀcatalyst.ꢀ
nextꢀ interestedꢀ inꢀ theꢀ activationꢀ ofꢀ iminesꢀ 12.ꢀ Anꢀ azaꢀ Diels-
Alderꢀ reactionꢀ ofꢀ N-phenylbenzaldimineꢀ 12aꢀ andꢀ Danishefskyꢀ
dieneꢀ 13ꢀ wasꢀ employedꢀ asꢀ aꢀ modelꢀ reactionꢀ toꢀ evaluateꢀ theꢀ
c
abilityꢀ ofꢀ sulfoniumꢀ saltꢀ catalystsꢀ forꢀ theꢀ activationꢀ ofꢀ iminesꢀ
14,15
(
ꢀ
Schemeꢀ 2).
ꢀ Inꢀ thisꢀ reaction,ꢀ sulfoniumꢀ iodideꢀ 2aꢀ showedꢀ
ꢀ Toꢀ furtherꢀ investigateꢀ theꢀ hydrogen-bondingꢀ interactionꢀ
betweenꢀ theꢀ αꢀ hydrogenꢀ atomsꢀ ofꢀ sulfoniumꢀ saltsꢀ andꢀ theꢀ
higherꢀ reactivityꢀ thanꢀ ammoniumꢀ iodidesꢀ 1aꢀ andꢀ 3a.ꢀ Also,ꢀ
sulfoniumꢀ barfateꢀ 2bꢀ wasꢀ aꢀ moreꢀ effectiveꢀ catalystꢀ thanꢀ
2
ꢀ|ꢀJ.ꢀName.,ꢀ2012,ꢀ00,ꢀ1-3ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ

Page 3 of 4
Pleaseꢀd Co hꢀ ne omt ꢀ Ca do j mu s mt ꢀmarginsꢀ
ChemCommꢀ
ꢀCOMMUNICATIONꢀ
ammoniumꢀbarfatesꢀ1bꢀandꢀ3b,ꢀandꢀtheꢀreactionꢀwithꢀcatalystꢀ introducedꢀ iminesꢀ couldꢀ beꢀ employedꢀ forꢀ theVꢀierweaArctitcileoOnnꢀlitnoeꢀ
DOI: 10.1039/C6CC08411G
2bꢀgaveꢀtheꢀhighestꢀyieldꢀofꢀproductꢀ14aꢀ(98%ꢀyield).ꢀItꢀshouldꢀ obtainꢀproductsꢀ14b–14fꢀinꢀmoderateꢀtoꢀhighꢀyieldsꢀ(54–99%ꢀ
beꢀ notedꢀ thatꢀ theꢀ moreꢀ stericallyꢀ hinderedꢀ benzylsulfoniumꢀ yields).ꢀ Itꢀ shouldꢀ beꢀ notedꢀ thatꢀ theꢀ additionꢀ ofꢀ catalystꢀ 2b
barfateꢀ 4ꢀ showedꢀ reactivityꢀ thatꢀ wasꢀ inferiorꢀ toꢀ thatꢀ ofꢀ 2b.ꢀ producedꢀclearꢀaccelerationsꢀofꢀeachꢀreaction.ꢀ
ꢀ
OMe
Theseꢀresultsꢀcompletelyꢀagreeꢀwithꢀourꢀpreviousꢀobservationsꢀ
thatꢀ stericallyꢀ less-hinderedꢀ catalystsꢀ areꢀ moreꢀ effectiveꢀ inꢀ
Ar
2b
Ar
N
(10 mol %)
N
+
6
activatingꢀiminesꢀ12. ꢀ
b
CH2Cl2
°C, 3 h
R
H
R
O
0
R
OSiMe3
R
OSiMe
Ph
12
13
14
3
4
(
10 mol %)
N
O
Ph
Ph
Ph
N
+
N
N
N
Troc
Y
Troc
THF
6
b
R'
R'
Cl
or
6a
O
O
O
5
a or 5b (R = Me)
7
N
MeO
14b
2%
Ph
14c
99%
(without 2b : 9%)
14d
74%
Me
8
(
without 2b : 9%)
(without 2b : 17%)
R
N
N
Troc
Troc
Me
Cl
Ph
N
Ph
N
CO
2
N
O
+
O
7
b
O
7c
0
°C, 6 h
55%
–78 °C, 8 h
41%
(without 4 : 8%)
Ph
O
Cl
O
CCl
3
1
4e
1%
without 2b : 12%)
14f
54%
(
without 4 : 7%)
OSiMe
OMe
9
(
(without 2b : 20%)
CO Me
2
3
ꢀ
Schemeꢀ3ꢀꢀScopeꢀofꢀtheꢀazaꢀDiels-Alderꢀreaction.ꢀ
ꢀ
Y
6
a
ꢀ
theꢀ reductionꢀ ofꢀ iminesꢀ 12ꢀ withꢀ Hantzschꢀ esterꢀ 15ꢀ (Schemeꢀ
Furthermore,ꢀ sulfoniumꢀ barfateꢀ 2bꢀ efficientlyꢀ promotedꢀ
4
Y
N
TrocCl (10 mol %)
10
Troc
16
). ꢀ Theꢀ reactionsꢀ withꢀ catalystꢀ 2bꢀ gaveꢀ secondaryꢀ amineꢀ
+
4
THF
°C, 0.5 h
THF
Y
N
17
productsꢀ16a–16cꢀinꢀgoodꢀyieldsꢀ(67–81%ꢀyields). ꢀ
0
9
9
a (Y = H)
b (Y = Cl)
CO
2
Me
EtO C
CO Et
2b
Ar
N
2
2
Ar
N
(10 mol %)
HN
11
+
Troc
N
H
CH
25 °C, 6 h
2 2
Cl
reaction of 9a : 80% [10a/11a 6:1]
Y = H, –78 °C, 3 h)
R
H
R
(
1
2
15
16
Ph
reaction of 9b : 70% [10b/11b >30:1]
Y = Cl, 0 °C, 3 h)
ꢀ
Schemeꢀ 1ꢀ ꢀ Benzylsulfoniumꢀ barfate-catalyzedꢀ Mannich-typeꢀ
(
Cl
Ph
HN
HN
HN
reactions.ꢀ
ꢀ
ꢀ
Ph
Ph
MeO
OMe
16a
1%
without 2b : 14%)
16b
81%
16c
67%
catalyst
(10 mol %)
Ph
Ph
Ph
7
N
N
(
+
ꢀ
CH2Cl2
0 °C, 3 h
Ph
H
O
Schemeꢀ4ꢀꢀReductionꢀofꢀiminesꢀ12ꢀwithꢀHantzschꢀesterꢀ15.ꢀ
ꢀ
OSiMe3
1
2a
13
14a
ꢀ
Inꢀ summary,ꢀ weꢀ haveꢀ successfullyꢀ demonstratedꢀ thatꢀ
X
X
trialkylsulfoniumꢀ saltsꢀ canꢀ functionꢀ asꢀ hydrogen-bondingꢀ
catalysts.ꢀTheꢀstructureꢀandꢀbindingꢀabilitiesꢀofꢀsulfoniumꢀsaltsꢀ
wereꢀ discussedꢀ inꢀ thisꢀ studyꢀ basedꢀ onꢀ theꢀ X-rayꢀ crystalꢀ
without catalyst
MeO2C
N
CO2Me
N
4
%
a (X– = I ) : 64%
b (X– = BArF–) : 85%
–
3a (X– = I ) : 67%
–
1
1
1
3b (X– = BArF ) : 89%
–
structuresꢀandꢀ HꢀNMRꢀtitrationꢀstudies.ꢀTheꢀcatalyticꢀabilityꢀofꢀ
trialkylsulfoniumꢀ saltsꢀ wasꢀ superiorꢀ toꢀ thatꢀ ofꢀ theꢀ relatedꢀ
tetraalkylammoniumꢀ saltsꢀ inꢀ bothꢀ theꢀ Mannich-typeꢀ reactionꢀ
asꢀwellꢀasꢀinꢀtheꢀazaꢀDiels-Alderꢀreaction.ꢀThisꢀreportꢀrevealedꢀaꢀ
newꢀdimensionꢀofꢀsulfoniumꢀsaltꢀchemistryꢀinꢀorganicꢀsynthesisꢀ
onꢀ theꢀ basisꢀ ofꢀ theꢀ characteristicꢀ propertiesꢀ ofꢀ theꢀ acidicꢀ αꢀ
hydrogenꢀ atomsꢀ onꢀ alkylsulfoniumꢀ salts.ꢀ Furtherꢀ applicationsꢀ
ofꢀ sulfoniumꢀ saltsꢀ asꢀ catalystsꢀ areꢀ currentlyꢀ underwayꢀ inꢀ ourꢀ
group.ꢀ
I
BArF
BArF
S
S
S
Ph
2
a : 81%
2b : 98%
4 : 83%
ꢀ
Schemeꢀ2ꢀꢀEffectꢀofꢀcatalystsꢀinꢀtheꢀazaꢀDiels-Alderꢀreactionꢀofꢀ
imineꢀ12a.ꢀ
ꢀ
ꢀ
Thisꢀ workꢀ wasꢀ partiallyꢀ supportedꢀ byꢀ aꢀ Grant-in-Aidꢀ forꢀ
ꢀ TheꢀsubstrateꢀgeneralityꢀforꢀtheꢀazaꢀDiels-Alderꢀreactionꢀofꢀ
iminesꢀ12ꢀwasꢀexaminedꢀwithꢀcatalystꢀ2bꢀ(Schemeꢀ3).ꢀNotꢀonlyꢀ
substitutedꢀaromaticsꢀbutꢀalsoꢀheteroaromaticꢀandꢀalkylꢀgroup-
Scientificꢀ Research(C)ꢀ fromꢀ JSPS,ꢀ theꢀ Cooperativeꢀ Researchꢀ
Programꢀofꢀ"NetworkꢀJointꢀResearchꢀCenterꢀforꢀMaterialsꢀandꢀ
Devices",ꢀandꢀTheꢀNaitoꢀFoundation.ꢀ
Thisꢀjournalꢀisꢀ©ꢀTheꢀRoyalꢀSocietyꢀofꢀChemistryꢀ20xxꢀ
J.ꢀName.,ꢀ2013,ꢀ00,ꢀ1-3ꢀ|ꢀ3ꢀ

Pleaseꢀd Co hꢀ ne omt ꢀ Ca do j mu s mt ꢀmarginsꢀ
Page 4 of 4
COMMUNICATIONꢀ
ChemCommꢀ
Notesꢀandꢀreferencesꢀ
Andrusꢀ andꢀ D.ꢀ H.ꢀ Ess,ꢀ Org.ꢀ Lett.,ꢀ 2012,ꢀ 14,Vꢀie5w8A3r6tic;ꢀle(Oj)nꢀlinCe.ꢀ
Thomas,ꢀA.ꢀMilet,ꢀF.ꢀPeruchꢀandꢀB.ꢀBib Da Ol , ꢀI :P 1o0 l .y1 m0 3 .9ꢀ C/ Ch 6e CmC .0, ꢀ82 4 01 11 G3 ,ꢀ
4,ꢀ 3491;ꢀ (k)ꢀ C.ꢀ Thomas,ꢀ S.ꢀ Brutꢀ andꢀ B.ꢀ Bibal,ꢀ Tetrahedron,ꢀ
1
(a)ꢀG.ꢀA.ꢀOlah,ꢀAldrichimicaꢀActa,ꢀ1973,ꢀ
6
,ꢀ7;ꢀ(b)ꢀE.ꢀVedejsꢀandꢀ
F.ꢀG.ꢀWest,ꢀChem.ꢀRev.,ꢀ1986,ꢀ86,ꢀ941;ꢀ(c)ꢀG.ꢀK.ꢀS.ꢀPrakash,ꢀJ.ꢀ
Org.ꢀ Chem.,ꢀ 2006,ꢀ 71,ꢀ 3661;ꢀ (d)ꢀ Recentꢀ Developmentsꢀ inꢀ
Carbocationꢀ andꢀ Oniumꢀ Ionꢀ Chemistry,ꢀ ed.ꢀ K.ꢀ K.ꢀ Laali,ꢀ
Americanꢀ Chemicalꢀ Society,ꢀ Washingtonꢀ DC,ꢀ 2007ꢀ (ACSꢀ
SymposiumꢀSeriesꢀ965);ꢀ(e)ꢀJ.ꢀB.ꢀSweeney,ꢀChem.ꢀSoc.ꢀRev.,ꢀ
2014,ꢀ70,ꢀ1646;ꢀ(l)ꢀT.ꢀKamachiꢀandꢀK.ꢀYoshizawa,ꢀOrg.ꢀLett.,ꢀ
2014,ꢀ16,ꢀ472;ꢀ(m)ꢀC.ꢀP.ꢀJohnston,ꢀA.ꢀKothari,ꢀT.ꢀSergeieva,ꢀS.ꢀI.ꢀ
Okovytyy,ꢀ K.ꢀ E.ꢀ Jackson,ꢀ R.ꢀ S.ꢀ Patonꢀ andꢀ M.ꢀ D.ꢀ Smith,ꢀ Nat.ꢀ
Chem.,ꢀ2015,ꢀ7,ꢀ171;ꢀ(n)ꢀQ.ꢀPengꢀandꢀR.ꢀS.ꢀPaton,ꢀAcc.ꢀChem.ꢀ
Res.,ꢀ2016,ꢀ49,ꢀ1042;ꢀ(o)ꢀJ.ꢀNovacek,ꢀJ.ꢀA.ꢀIzzo,ꢀM.ꢀJ.ꢀVetticattꢀ
andꢀ M.ꢀ Waser,ꢀ Chem.–Eur.ꢀ J.,ꢀ 2016,ꢀ 22,ꢀ (DOI:ꢀ
10.1002/chem.201604153).ꢀ
Forꢀ reviewsꢀ onꢀ hydrogen-bondingꢀ catalysis,ꢀ see:ꢀ (a)ꢀ P.ꢀ R.ꢀ
Schreiner,ꢀ Chem.ꢀ Soc.ꢀ Rev.,ꢀ 2003,ꢀ 32,ꢀ 289;ꢀ (b)ꢀ P.ꢀ M.ꢀ Pihko,ꢀ
Angew.ꢀChem.,ꢀInt.ꢀEd.,ꢀ2004,ꢀ43,ꢀ2062;ꢀ(c)ꢀA.ꢀG.ꢀDoyleꢀandꢀE.ꢀ
N.ꢀJacobsen,ꢀChem.ꢀRev.,ꢀ2007,ꢀ107,ꢀ5713;ꢀ(d)ꢀT.ꢀJ.ꢀAuvil,ꢀA.ꢀG.ꢀ
SchaferꢀandꢀA.ꢀE.ꢀMattson,ꢀEur.ꢀJ.ꢀOrg.ꢀChem.,ꢀ2014,ꢀ2633.ꢀ
R.ꢀGerdil,ꢀHelv.ꢀChim.ꢀActa,ꢀ1974,ꢀ57,ꢀ489.ꢀ
2
4
009,ꢀ38,ꢀ1027;ꢀ(f)ꢀX.ꢀGuoꢀandꢀW.ꢀHu,ꢀAcc.ꢀChem.ꢀRes.,ꢀ2013,ꢀ
6,ꢀ 2427;ꢀ (g)ꢀ S.ꢀ Preshlock,ꢀ M.ꢀ Tredwellꢀ andꢀ V.ꢀ Gouverneur,ꢀ
Chem.ꢀRev.,ꢀ2016,ꢀ116,ꢀ719.ꢀ
8
9
2
3
(a)ꢀ L.ꢀ Kürtiꢀ andꢀ B.ꢀ Czakó,ꢀ Strategicꢀ Applicationsꢀ ofꢀ Namedꢀ
ReactionsꢀinꢀOrganicꢀSynthesis,ꢀElsevierꢀAcademicꢀPress,ꢀSanꢀ
Diego,ꢀ 2005;ꢀ (b)ꢀ J.ꢀ J.ꢀ Li,ꢀ Nameꢀ Reactions,ꢀ Springer,ꢀ Berlin,ꢀ
2
006;ꢀ (c)ꢀ Nameꢀ Reactionsꢀ forꢀ Functionalꢀ Groupꢀ
Transformations,ꢀ ed.ꢀ J.ꢀ J.ꢀ Li,ꢀ Johnꢀ Wileyꢀ &ꢀ Sons,ꢀ Hoboken,ꢀ
2
007;ꢀ (d)ꢀ Comprehensiveꢀ Organicꢀ Nameꢀ Reactionsꢀ andꢀ 10 Anotherꢀ bindingꢀ modeꢀ wasꢀ alsoꢀ observedꢀ inꢀ X-rayꢀ crystalꢀ
Reagents,ꢀed.ꢀZ.ꢀWang,ꢀJohnꢀWileyꢀ&ꢀSons,ꢀHoboken,ꢀ2009.ꢀ
structureꢀofꢀ2aꢀ(Fig.ꢀS1ꢀinꢀSupplementaryꢀInformation).ꢀ
Forꢀ recentꢀ examplesꢀ ofꢀ sufoniumꢀ saltꢀ reagentsꢀ inꢀ organicꢀ 11 (a)ꢀX.-M.ꢀZhangꢀandꢀF.ꢀG.ꢀBordwell,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ1994,ꢀ
synthesis,ꢀsee:ꢀ(a)ꢀR.ꢀK.ꢀKunzꢀandꢀD.ꢀW.ꢀC.ꢀMacMillan,ꢀJ.ꢀAm.ꢀ
Chem.ꢀ Soc.,ꢀ 2005,ꢀ 127,ꢀ 3240;ꢀ (b)ꢀ E.ꢀ M.ꢀ McGarrigle,ꢀ E.ꢀ L.ꢀ
116,ꢀ 968;ꢀ (b)ꢀ J.-P.ꢀ Cheng,ꢀ B.ꢀ Liuꢀ andꢀ X.-M.ꢀ Zhang,ꢀ J.ꢀ Org.ꢀ
Chem.,ꢀ1998,ꢀ63,ꢀ7574.ꢀ
Myers,ꢀ O.ꢀ Illa,ꢀ M.ꢀ A.ꢀ Shaw,ꢀ S.ꢀ L.ꢀ Richesꢀ andꢀ V.ꢀ K.ꢀ Aggarwal,ꢀ 12 (a)ꢀ M.ꢀ S.ꢀ Taylor,ꢀ N.ꢀ Tokunagaꢀ andꢀ E.ꢀ N.ꢀ Jacobsen,ꢀ Angew.ꢀ
Chem.ꢀRev.,ꢀ2007,ꢀ107,ꢀ5841;ꢀ(c)ꢀS.ꢀLakhdar,ꢀR.ꢀAppelꢀandꢀH.ꢀ
Mayr,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.,ꢀ2009,ꢀ48,ꢀ5034;ꢀ(d)ꢀS.ꢀLinꢀandꢀE.ꢀ
Chem.,ꢀ Int.ꢀ Ed.,ꢀ 2005,ꢀ 44,ꢀ 6700;ꢀ (b)ꢀ A.ꢀ G.ꢀ Schafer,ꢀ J.ꢀ M.ꢀ
Wieting,ꢀ T.ꢀ J.ꢀ Fisherꢀ andꢀ A.ꢀ E.ꢀ Mattson,ꢀ Angew.ꢀ Chem.,ꢀ Int.ꢀ
Ed.,ꢀ 2013,ꢀ 52,ꢀ 11321;ꢀ (c)ꢀ J.ꢀ M.ꢀ Wieting,ꢀ T.ꢀ J.ꢀ Fisher,ꢀ A.ꢀ G.ꢀ
Schafer,ꢀM.ꢀD.ꢀVisco,ꢀJ.ꢀC.ꢀGallucciꢀandꢀA.ꢀE.ꢀMattson,ꢀEur.ꢀJ.ꢀ
Org.ꢀChem.,ꢀ2015,ꢀ525;ꢀ(d)ꢀM.ꢀZurro,ꢀS.ꢀAsmus,ꢀJ.ꢀBamberger,ꢀ
S.ꢀBeckendorfꢀandꢀO.ꢀGarcíaꢀMancheño,ꢀChem.–Eur.ꢀJ.,ꢀ2016,ꢀ
22,ꢀ 3785;ꢀ seeꢀ also:ꢀ (e)ꢀ S.ꢀ E.ꢀ Reisman,ꢀ A.ꢀ G.ꢀ Doyleꢀ andꢀ E.ꢀ N.ꢀ
Jacobsen,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2008,ꢀ130,ꢀ7198;ꢀ(f)ꢀF.ꢀKniep,ꢀS.ꢀ
H.ꢀ Jungbauer,ꢀ Q.ꢀ Zhang,ꢀ S.ꢀ M.ꢀ Walter,ꢀ S.ꢀ Schindler,ꢀ I.ꢀ
Schnapperelle,ꢀE.ꢀHerdtweckꢀandꢀS.ꢀM.ꢀHuber,ꢀAngew.ꢀChem.,ꢀ
Int.ꢀEd.,ꢀ2013,ꢀ52,ꢀ7028;ꢀ(g)ꢀA.ꢀBerkessel,ꢀS.ꢀDas,ꢀD.ꢀPekelꢀandꢀ
J.ꢀM.ꢀNeudörfl,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.,ꢀ2014,ꢀ53,ꢀ11660;ꢀ(h)ꢀS.ꢀ
H.ꢀJungbauerꢀandꢀS.ꢀM.ꢀHuber,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2015,ꢀ137,ꢀ
12110.ꢀ
N.ꢀ Jacobsen,ꢀ Nat.ꢀ Chem.,ꢀ 2012,ꢀ
Roiser,ꢀ K.ꢀ Zielke,ꢀ R.ꢀ Robietteꢀ andꢀ M.ꢀ Waser,ꢀ Chem.–Eur.ꢀ J.,ꢀ
016,ꢀ 22,ꢀ 11422;ꢀ (f)ꢀ A.ꢀ P.ꢀ Pulisꢀ andꢀ D.ꢀ J.ꢀ Procter,ꢀ Angew.ꢀ
4,ꢀ 817;ꢀ (e)ꢀ J.ꢀ Novacek,ꢀ L.ꢀ
2
Chem.,ꢀInt.ꢀEd.,ꢀ2016,ꢀ55,ꢀ9842.ꢀ
4
(a)ꢀ E.ꢀ V.ꢀ Dehmlowꢀ andꢀ S.ꢀ S.ꢀ Dehmlow,ꢀ Phaseꢀ Transferꢀ
Catalysis,ꢀ3rdꢀed.,ꢀVCH,ꢀWeinheim,ꢀ1993;ꢀ(b)ꢀC.ꢀM.ꢀStarks,ꢀC.ꢀL.ꢀ
LiottaꢀandꢀM.ꢀHalpern,ꢀPhase-TransferꢀCatalysis,ꢀChapmanꢀ&ꢀ
Hall,ꢀ Newꢀ York,ꢀ 1994;ꢀ (c)ꢀ Handbookꢀ ofꢀ Phase-Transferꢀ
Catalysis,ꢀeds.ꢀY.ꢀSassonꢀandꢀR.ꢀNeumann,ꢀBlackieꢀAcademicꢀ
&
ꢀ Professional,ꢀ London,ꢀ 1997;ꢀ (d)ꢀ Phase-Transferꢀ Catalysis,ꢀ
ed.ꢀ M.ꢀ E.ꢀ Halpern,ꢀ Americanꢀ Chemicalꢀ Society,ꢀ Washingtonꢀ
DC,ꢀ 1997ꢀ (ACSꢀ Symposiumꢀ Seriesꢀ 659);ꢀ (e)ꢀ M.ꢀ J.ꢀ O’Donnell,ꢀ
AldrichimicaꢀActa,ꢀ2001,ꢀ34,ꢀ3;ꢀ(f)ꢀT.ꢀOoiꢀandꢀK.ꢀMaruoka,ꢀAcc.ꢀ 13 (a)ꢀ T.ꢀ Itoh,ꢀ M.ꢀ Miyazaki,ꢀ K.ꢀ Nagataꢀ andꢀ A.ꢀ Ohsawa,ꢀ
Chem.ꢀRes.,ꢀ2004,ꢀ37,ꢀ526;ꢀ(g)ꢀT.ꢀOoiꢀandꢀK.ꢀMaruoka,ꢀAngew.ꢀ
Chem.,ꢀ Int.ꢀ Ed.,ꢀ 2007,ꢀ 46,ꢀ 4222;ꢀ (h)ꢀ Asymmetricꢀ Phase-
Transferꢀ Catalysis,ꢀ ed.ꢀ K.ꢀ Maruoka,ꢀ Wiley-VCH,ꢀ Weinheim,ꢀ
Heterocycles,ꢀ1997,ꢀ46,ꢀ83;ꢀ(b)ꢀM.ꢀTakamura,ꢀK.ꢀFunabashi,ꢀM.ꢀ
KanaiꢀandꢀM.ꢀShibasaki,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2000,ꢀ122,ꢀ6327;ꢀ
(c)ꢀH.ꢀRudler,ꢀB.ꢀDenise,ꢀY.ꢀXu,ꢀA.ꢀParlierꢀandꢀJ.ꢀVaissermann,ꢀ
Eur.ꢀ J.ꢀ Org.ꢀ Chem.,ꢀ 2005,ꢀ 3724;ꢀ (d)ꢀ Y.ꢀ Yamaoka,ꢀ H.ꢀ Miyabeꢀ
andꢀY.ꢀTakemoto,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2007,ꢀ129,ꢀ6686;ꢀ(e)ꢀM.ꢀ
Zurro,ꢀ S.ꢀ Asmus,ꢀ S.ꢀ Beckendorf,ꢀ C.ꢀ Mück-Lichtenfeldꢀ andꢀ O.ꢀ
GarcíaꢀMancheño,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ2014,ꢀ136,ꢀ13999.ꢀ
2
7
008;ꢀ (i)ꢀ S.-s.ꢀ Jewꢀ andꢀ H.-g.ꢀ Park,ꢀ Chem.ꢀ Commun.,ꢀ 2009,ꢀ
090;ꢀ(j)ꢀT.ꢀWerner,ꢀAdv.ꢀSynth.ꢀCatal., 2009,ꢀ351,ꢀ1469;ꢀ(k)ꢀD.ꢀ
2012,ꢀ 10,ꢀ
327;ꢀ(l)ꢀJ.ꢀNovacekꢀandꢀM.ꢀWaser,ꢀEur.ꢀJ.ꢀOrg.ꢀChem., 2013,ꢀ
ꢀ
Endersꢀ andꢀ T.ꢀ V.ꢀ Nguyen,ꢀ Org.ꢀ Biomol.ꢀ Chem.,
5
6
Ed.,ꢀ 2013,ꢀ 52,ꢀ 4312;ꢀ (n)ꢀ S.ꢀ Kaneko,ꢀ Y.ꢀ Kumatabaraꢀ andꢀ S.ꢀ
Shirakawa,ꢀOrg.ꢀBiomol.ꢀChem., 2016,ꢀ14,ꢀ5367;ꢀ(o)ꢀS.ꢀLiu,ꢀY.ꢀ
KumatabaraꢀandꢀS.ꢀShirakawa,ꢀGreenꢀChem., 2016,ꢀ18,ꢀ331.ꢀ
Forꢀ trialꢀ applicationꢀ ofꢀ tertiaryꢀ sulfoniumꢀ saltsꢀ asꢀ phase-
ꢀ
ꢀ
37;ꢀ (m)ꢀ S.ꢀ Shirakawaꢀ andꢀ K.ꢀ Maruoka,ꢀ Angew.ꢀ Chem.,ꢀ Int.ꢀ 14 (a)ꢀY.ꢀYuan,ꢀX.ꢀLiꢀandꢀK.ꢀDing,ꢀOrg.ꢀLett.,ꢀ2002,ꢀ
Loncaric,ꢀ K.ꢀ Manabeꢀ andꢀ S.ꢀ Kobayashi,ꢀ Chem.ꢀ Commun.,ꢀ
4,ꢀ3309;ꢀ(b)ꢀC.ꢀ
ꢀ
2003,ꢀ574;ꢀ(c)ꢀY.ꢀPark,ꢀE.ꢀPark,ꢀH.ꢀJung,ꢀY.-J.ꢀLee,ꢀS.-s.ꢀJewꢀandꢀ
H.-g.ꢀ Park,ꢀ Tetrahedron,ꢀ 2011,ꢀ 67,ꢀ 1166;ꢀ (d)ꢀ Y.ꢀ Takeda,ꢀ D.ꢀ
Hisakuni,ꢀC.-H.ꢀLinꢀandꢀS.ꢀMinakata,ꢀOrg.ꢀLett.,ꢀ2015,ꢀ17,ꢀ318.ꢀ
ꢀ
5
transferꢀcatalysts,ꢀsee:ꢀ(a)ꢀS.ꢀKondo,ꢀY.ꢀTakedaꢀandꢀK.ꢀTsuda,ꢀ 15 Otherꢀcontrolꢀexperimentsꢀwereꢀalsoꢀperformedꢀ(SchemeꢀS1ꢀ
Synthesis,ꢀ1988,ꢀ403;ꢀ(b)ꢀX.-Z.ꢀZhang,ꢀY.-H.ꢀDeng,ꢀX.ꢀYan,ꢀK.-Y.ꢀ
inꢀSupplementaryꢀInformation).ꢀ
Yu,ꢀF.-X.ꢀWang,ꢀX.-Y.ꢀMaꢀandꢀC.-A.ꢀFan,ꢀJ.ꢀOrg.ꢀChem.,ꢀ2016,ꢀ 16 (a)ꢀ M.ꢀ Rueping,ꢀ C.ꢀ Azap,ꢀ E.ꢀ Sugionoꢀ andꢀ T.ꢀ Theissmann,ꢀ
,ꢀ5655.ꢀ
Synlett,ꢀ 2005,ꢀ 2367;ꢀ (b)ꢀ D.ꢀ Menche,ꢀ J.ꢀ Hassfeld,ꢀ J.ꢀ Li,ꢀ G.ꢀ
Menche,ꢀA.ꢀRitterꢀandꢀS.ꢀRudolph,ꢀOrg.ꢀLett.,ꢀ2006,ꢀ ,ꢀ741;ꢀ(c)ꢀ
8
1
6
7
(a)ꢀS.ꢀShirakawa,ꢀS.ꢀLiu,ꢀS.ꢀKaneko,ꢀY.ꢀKumatabara,ꢀA.ꢀFukuda,ꢀ
Y.ꢀOmagariꢀandꢀK.ꢀMaruoka,ꢀAngew.ꢀChem.,ꢀInt.ꢀEd.,ꢀ2015,ꢀ54,ꢀ
8
D.ꢀMencheꢀandꢀF.ꢀArikan,ꢀSynlett,ꢀ2006,ꢀ841;ꢀ(d)ꢀA.ꢀKumar,ꢀS.ꢀ
Sharmaꢀ andꢀ R.ꢀ A.ꢀ Maurya,ꢀ Adv.ꢀ Synth.ꢀ Catal.,ꢀ 2010,ꢀ 352,ꢀ
2227;ꢀ(e)ꢀP.ꢀBachu,ꢀC.ꢀZhuꢀandꢀT.ꢀAkiyama,ꢀTetrahedronꢀLett.,ꢀ
2013,ꢀ54,ꢀ3977;ꢀ(f)ꢀW.ꢀHe,ꢀY.-C.ꢀGeꢀandꢀC.-H.ꢀTan,ꢀOrg.ꢀLett.,ꢀ
2014,ꢀ16,ꢀ3244.ꢀ
1
5767;ꢀ(b)ꢀY.ꢀKumatabara,ꢀS.ꢀKaneko,ꢀS.ꢀNakata,ꢀS.ꢀShirakawaꢀ
andꢀK.ꢀMaruoka,ꢀChem.–AsianꢀJ.,ꢀ2016,ꢀ11,ꢀ2126.ꢀ
Forꢀrelatedꢀstudies,ꢀsee:ꢀ(a)ꢀM.ꢀT.ꢀReetz,ꢀAngew.ꢀChem.,ꢀInt.ꢀ
Ed.ꢀ Engl.,ꢀ 1988,ꢀ 27,ꢀ 994;ꢀ (b)ꢀ M.ꢀ T.ꢀ Reetz,ꢀ S.ꢀ Hütteꢀ andꢀ R.ꢀ
Goddard,ꢀJ.ꢀAm.ꢀChem.ꢀSoc.,ꢀ1993,ꢀ115,ꢀ9339;ꢀ(c)ꢀM.ꢀT.ꢀReetz,ꢀ 17 Noꢀcatalystꢀdecompositionꢀwasꢀobservedꢀafterꢀtheꢀreaction.ꢀ
S.ꢀHütteꢀandꢀR.ꢀGoddard,ꢀJ.ꢀPhys.ꢀOrg.ꢀChem.,ꢀ1995,ꢀ ,ꢀ231;ꢀ
d)ꢀM.ꢀT.ꢀReetz,ꢀS.ꢀHütte,ꢀR.ꢀGoddardꢀandꢀC.ꢀRobyr,ꢀChem.–
8
(
Eur.ꢀJ.,ꢀ1996,ꢀ2,ꢀ382;ꢀ(e)ꢀM.ꢀT.ꢀReetz,ꢀS.ꢀHütteꢀandꢀR.ꢀGoddard,ꢀ
J.ꢀPrakt.ꢀChem.,ꢀ1999,ꢀ341,ꢀ297;ꢀ(f)ꢀR.ꢀGoddard,ꢀH.ꢀM.ꢀHerzogꢀ
andꢀ M.ꢀ T.ꢀ Reetz,ꢀ Tetrahedron,ꢀ 2002,ꢀ 58,ꢀ 7847;ꢀ (g)ꢀ C.ꢀ E.ꢀ
Cannizzaroꢀ andꢀ K.ꢀ N.ꢀ Houk,ꢀ J.ꢀ Am.ꢀ Chem.ꢀ Soc.,ꢀ 2002,ꢀ 124,ꢀ
7
163;ꢀ (h)ꢀ T.ꢀ Ohshima,ꢀ T.ꢀ Shibuguchi,ꢀ Y.ꢀ Fukutaꢀ andꢀ M.ꢀ
Shibasaki,ꢀTetrahedron,ꢀ2004,ꢀ60,ꢀ7743;ꢀ(i)ꢀT.ꢀC.ꢀCook,ꢀM.ꢀB.ꢀ
4
ꢀ|ꢀJ.ꢀName.,ꢀ2012,ꢀ00,ꢀ1-3ꢀ
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