Cu(I)-catalyzed cascade reaction of N-tosylhydrazones with 3-butyn-1-ol: A new synthesis of tetrahydrofurans

Article abstract of DOI:10.1016/S1872-2067(16)62565-2

The Cu(I)-catalyzed cascade coupling/cyclization reaction of N-tosylhydrazones with 3-butyn-1-ol has been explored. This new strategy represents a simple platform for the synthesis of tetrahydrofurans in moderate to good yields.

Full text of DOI:10.1016/S1872-2067(16)62565-2

ChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ115–122
ꢀ
ꢀ ꢀ ꢀ
ꢀ ꢀ ꢀ ꢀ
a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m
ꢀ
j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c h n j c
ꢀ
ꢀ
Article
Cu(I)‐catalyzedꢀcascadeꢀreactionꢀofꢀN‐tosylhydrazonesꢀwithꢀ
‐butyn‐1‐ol:ꢀAꢀnewꢀsynthesisꢀofꢀtetrahydrofuransꢀ
3
ꢀa
ꢀa
ꢀa
ꢀa
ꢀa,b,
MohammadꢀLokmanꢀHossain ,ꢀKangꢀWang ,ꢀFeiꢀYe ,ꢀYanꢀZhang ,ꢀJianboꢀWang *
ꢀ
aꢀBeijingꢀNationalꢀLaboratoryꢀofꢀMolecularꢀSciencesꢀ(BNLMS)ꢀandꢀKeyꢀLaboratoryꢀofꢀBioorganicꢀChemistryꢀandꢀMolecularꢀEngineeringꢀofꢀMinistryꢀofꢀEd‐
ucation,ꢀCollegeꢀofꢀChemistryꢀandꢀMolecularꢀEngineering,ꢀPekingꢀUniversity,ꢀBeijingꢀ100871,ꢀChinaꢀ
bꢀStateꢀKeyꢀLaboratoryꢀofꢀOrganometallicꢀChemistry,ꢀChineseꢀAcademyꢀofꢀSciences,ꢀShanghaiꢀ200032,ꢀChinaꢀ
A R T I C L E ꢀ I N F O ꢀ
A B S T R A C T ꢀ
Articleꢀhistory:ꢀ
TheꢀCu(I)‐catalyzedꢀcascadeꢀcoupling/cyclizationꢀreactionꢀofꢀN‐tosylhydrazonesꢀwithꢀ3‐butyn‐1‐olꢀ
hasꢀbeenꢀexplored.ꢀThisꢀnewꢀstrategyꢀrepresentsꢀaꢀsimpleꢀplatformꢀforꢀtheꢀsynthesisꢀofꢀtetrahydro‐
furansꢀinꢀmoderateꢀtoꢀgoodꢀyields.ꢀ
Receivedꢀ26ꢀAugustꢀ2016ꢀ
Acceptedꢀ16ꢀSeptemberꢀ2016ꢀ
Publishedꢀ5ꢀJanuaryꢀ2017ꢀ
©ꢀ2016,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences.
PublishedꢀbyꢀElsevierꢀB.V.ꢀAllꢀrightsꢀreserved.
Keywords:ꢀ
Copperꢀcatalysisꢀ
Alleneꢀ
Tetrahydrofuranꢀ
Crossꢀcouplingꢀ
Terminalꢀalkynes
1.ꢀ ꢀ Introductionꢀ
cross‐couplingꢀ ofꢀ terminalꢀ alkynesꢀ andꢀ N‐tosylhydrazonesꢀ asꢀ
anꢀefficientꢀstrategyꢀforꢀtheꢀformationꢀofꢀtri‐substitutedꢀallenesꢀ
N‐Tosylhydrazonesꢀ areꢀ usefulꢀ syntheticꢀ intermediatesꢀ thatꢀ
(Schemeꢀ 1(A))ꢀ [8].ꢀ Weꢀ subsequentlyꢀ modifiedꢀ andꢀ simplifiedꢀ
thisꢀmethodology,ꢀresultingꢀinꢀtheꢀdevelopmentꢀofꢀseveralꢀeffi‐
cientꢀmethodsꢀforꢀtheꢀconstructionꢀofꢀ1,3‐disubstitutedꢀallenesꢀ
[9]ꢀ andꢀ tetra‐substitutedꢀ allenesꢀ [10]ꢀ byꢀ theꢀ Cu‐catalyzedꢀ
cross‐couplingꢀ reactionsꢀ ofꢀ terminalꢀ alkynesꢀ andꢀ
N‐tosylhydrazones.ꢀTheꢀworkꢀrepresentsꢀfurtherꢀextensionsꢀofꢀ
ourꢀpreviousꢀstudiesꢀonꢀCu(I)‐catalyzedꢀalleneꢀsynthesisꢀfromꢀ
terminalꢀalkynesꢀandꢀN‐tosylhydrazones.ꢀ ꢀ
TheꢀCu‐carbeneꢀspeciesꢀinvolvedꢀinꢀthisꢀtypeꢀofꢀreactionꢀareꢀ
formedꢀ fromꢀ theꢀ inꢀsitu‐generatedꢀ diazoꢀ substrate,ꢀ whichꢀ un‐
dergoesꢀaꢀmigratoryꢀinsertionꢀreaction,ꢀfollowedꢀbyꢀaꢀprotona‐
tionꢀorꢀnucleophilicꢀsubstitutionꢀstepꢀtoꢀgiveꢀtheꢀalleneꢀproduct.ꢀ
Sinceꢀallenesꢀ areꢀreactiveꢀ structuresꢀthatꢀcanꢀ undergoꢀ aꢀwideꢀ
rangeꢀofꢀtransformationsꢀ[11–19],ꢀweꢀenvisagedꢀthatꢀitꢀcouldꢀbeꢀ
haveꢀbeenꢀemployedꢀinꢀorganicꢀchemistryꢀforꢀalmostꢀ60ꢀyears.ꢀ
Compoundsꢀbelongingꢀtoꢀthisꢀparticularꢀclassꢀareꢀairꢀandꢀmois‐
tureꢀstableꢀandꢀcanꢀbeꢀreadilyꢀpreparedꢀbyꢀtheꢀcondensationꢀofꢀ
aldehydesꢀorꢀketonesꢀwithꢀcommerciallyꢀavailableꢀtosylhydra‐
zine.ꢀInꢀparticular,ꢀN‐tosylhydrazonesꢀhaveꢀbeenꢀprovenꢀtoꢀbeꢀ
usefulꢀ substratesꢀ forꢀ theꢀ inꢀ situꢀ generationꢀ ofꢀ non‐stabilizedꢀ
diazoꢀ compoundsꢀ throughꢀ theꢀ Bamford–Stevensꢀ reactionꢀ [1].ꢀ
Theꢀdiazoꢀcompoundsꢀgeneratedꢀinꢀthisꢀwayꢀhaveꢀbeenꢀstudiedꢀ
extensivelyꢀ inꢀ termsꢀ ofꢀ theirꢀ applicationꢀ toꢀ catalyticꢀ carbeneꢀ
transferꢀreactionsꢀ[2].ꢀMoreꢀrecently,ꢀN‐tosylhydrazonesꢀ haveꢀ
beenꢀ establishedꢀ asꢀ versatileꢀ substratesꢀ inꢀ transi‐
tion‐metal‐catalyzedꢀ cross‐couplingꢀ reactionsꢀ [3–7].ꢀ Inꢀ thisꢀ
context,ꢀ weꢀ previouslyꢀ reportedꢀ theꢀ Cu(I)‐catalyzedꢀ
*ꢀCorrespondingꢀauthor.ꢀTel:ꢀ+86‐10‐62757248;ꢀFax:ꢀ+86‐10‐62751708;ꢀE‐mail:ꢀwangjb@pku.edu.cnꢀ ꢀ
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀNationalꢀBasicꢀResearchꢀProgramꢀofꢀChinaꢀ(973ꢀProgram,ꢀ2015CB856600)ꢀandꢀtheꢀNationalꢀNaturalꢀScienceꢀFounda‐
tionꢀofꢀChinaꢀ(21472004,ꢀ21332002).ꢀ
DOI:ꢀ10.1016/S1872‐2067(16)62565‐2ꢀ|ꢀhttp://www.sciencedirect.com/science/journal/18722067ꢀ|ꢀChin.ꢀJ.ꢀCatal.,ꢀVol.ꢀ38,ꢀNo.ꢀ1,ꢀJanuaryꢀ2017ꢀ ꢀ ꢀ

116ꢀ
MohammadꢀLokmanꢀHossainꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ115–122ꢀ
edꢀinꢀpartsꢀperꢀmillionꢀ(ppm)ꢀrelativeꢀtoꢀtheꢀchemicalꢀshiftꢀofꢀ
(A) Ref. [8]
tetramethylsilaneꢀ(TMS),ꢀwhichꢀwasꢀusedꢀasꢀanꢀinternalꢀrefer‐
ence.ꢀInfraredꢀ(IR)ꢀspectraꢀwereꢀrecordedꢀonꢀNicoletꢀiS10ꢀandꢀ
theꢀpeaksꢀreportedꢀinꢀwavenumbersꢀ(cm ).ꢀHRMSꢀanalysisꢀwasꢀ
R
R
R"
H
cat. Cu(I)
base
NNHTs
+
R"
R'
–1
R'
conductedꢀonꢀBrukerꢀAPEXꢀIVꢀFTMSꢀusingꢀaꢀFT‐ICRꢀmassꢀana‐
R"
R"
lyzer.ꢀ Theꢀ N‐tosylhydrazonesꢀ evaluatedꢀ inꢀ theꢀ currentꢀ studyꢀ
N2
CuI
R"
CuI
R'
ꢀ
CuI
H
wereꢀ preparedꢀ usingꢀaꢀliteratureꢀ procedureꢀ[2]. Unlessꢀother‐
R
R'
R
wiseꢀ noted,ꢀ materialsꢀ obtainedꢀ fromꢀ commercialꢀ suppliersꢀ
wereꢀusedꢀasꢀsuppliedꢀwithoutꢀfurtherꢀpurification.ꢀ ꢀ
R
R'
(B) Ref. [22]
2.2.ꢀ ꢀ GeneralꢀprocedureꢀforꢀtheꢀCu(I)‐catalyzedꢀreactionꢀofꢀ
N‐tosylhydrazonesꢀ1a–gꢀwithꢀ3‐butyn‐1‐olꢀ
NNHTs
cat. Cu(I)
base
+
H
R
Ar
H
X
R
3‐Butyn‐1‐olꢀ(2,ꢀ42ꢀmg,ꢀ0.6ꢀmmol)ꢀwasꢀaddedꢀtoꢀaꢀmixtureꢀofꢀ
CuIꢀ(3.8ꢀmg,ꢀ0.02ꢀmmol),ꢀbathophenanthrolineꢀ(6.64ꢀmg,ꢀ0.02ꢀ
mmol),ꢀ tetrabutylammoniumꢀ bromideꢀ (TBAB)ꢀ (19.3ꢀ mg,ꢀ 0.06ꢀ
mmol),ꢀLiO Buꢀ(48ꢀmg,ꢀ0.6ꢀmmol)ꢀandꢀN‐tosylhydrazoneꢀ(1a,ꢀ70ꢀ
mg,ꢀ0.2ꢀmmol)ꢀinꢀ1,4‐dioxaneꢀ(1ꢀmL)ꢀunderꢀnitrogen,ꢀandꢀtheꢀ
resultingꢀmixtureꢀwasꢀstirredꢀatꢀ110ꢀ°Cꢀforꢀ4ꢀh.ꢀUponꢀcomple‐
tionꢀ ofꢀ theꢀ reaction,ꢀ asꢀ determinedꢀ byꢀ TLC,ꢀ theꢀ reactionꢀ wasꢀ
cooledꢀtoꢀroomꢀtemperatureꢀandꢀtreatedꢀwithꢀTsOHꢀ(68.8ꢀmg,ꢀ
CuI
R
Ar =
t
Ar
H
XH
R
X = O or NH
H
XH
(C) This report
0
.4ꢀmmol),ꢀandꢀtheꢀresultingꢀmixtureꢀwasꢀstirredꢀforꢀ2ꢀhꢀatꢀ80ꢀ
H
NNHTs
+
OH cat. Cu(I)
base
O
R
°C.ꢀTheꢀreactionꢀwasꢀthenꢀcooledꢀtoꢀambientꢀtemperatureꢀandꢀ
OH
CuI
Ar
evaporatedꢀtoꢀdrynessꢀtoꢀgiveꢀaꢀcrudeꢀmixture,ꢀwhichꢀwasꢀpuri‐
fiedꢀbyꢀ columnꢀ chromatographyꢀoverꢀ silicaꢀgelꢀtoꢀaffordꢀ pureꢀ
Ar
R
Ar
R
3
aꢀasꢀaꢀwhiteꢀsolidꢀ(35ꢀmg,ꢀ75%).ꢀ
2‐(Diphenylmethylene)tetrahydrofuranꢀ(3a).ꢀWhiteꢀsolidꢀ(35ꢀ
Schemeꢀ1.ꢀSynthesisꢀandꢀtandemꢀtransformationꢀofꢀallenesꢀthroughꢀthe
Cu(I)‐catalyzedꢀ cross‐couplingꢀ ofꢀ N‐tosylhydrazonesꢀ withꢀ terminalꢀ
alkynes.ꢀ
mg,ꢀ 75%);ꢀ mpꢀ =ꢀ 101–103ꢀ °C;ꢀ R
EtOAc/petroleumꢀether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl )ꢀδꢀ7.38ꢀ(d,ꢀJꢀ
f
ꢀ =ꢀ 0.55ꢀ (1:100,ꢀ
1
3
possibleꢀ toꢀ interceptꢀ theseꢀ intermediatesꢀ inꢀ aꢀ cascadeꢀ trans‐
formationꢀsequence,ꢀtherebyꢀprovidingꢀfacileꢀaccessꢀtoꢀincreas‐
inglyꢀcomplexꢀstructures.ꢀInꢀthisꢀcontext,ꢀweꢀhaveꢀshownꢀthatꢀ
theꢀalleneꢀintermediatesꢀgeneratedꢀbyꢀtheꢀCu(I)‐catalyzedꢀcou‐
plingꢀ ofꢀ N‐tosylhydrazonesꢀ withꢀ terminalꢀ alkynesꢀ undergoꢀ
=ꢀ7.6ꢀHz,ꢀ2H),ꢀ7.31ꢀ(t,ꢀJꢀ=ꢀ7.4ꢀHz,ꢀ2H),ꢀ7.26–7.19ꢀ(m,ꢀ5H),ꢀ7.11ꢀ(t,ꢀ
Jꢀ=ꢀ7.3ꢀHz,ꢀ1H),ꢀ4.26ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀHz,ꢀ2H),ꢀ2.61ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ
13
2.01ꢀ(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl )ꢀδꢀ155.2,ꢀ142.1,ꢀ139.9,ꢀ
3
130.5,ꢀ128.9,ꢀ128.2,ꢀ127.7,ꢀ126.0,ꢀ125.3,ꢀ110.6,ꢀ71.3,ꢀ30.2,ꢀ24.9;ꢀ
IRꢀ(film):ꢀ3030,ꢀ2289,ꢀ1641,ꢀ1599,ꢀ1497,ꢀ1203,ꢀ1175,ꢀ1037,ꢀ910,ꢀ
–1
+
6π‐electronꢀcycloadditionꢀandꢀisomerizationꢀreactionsꢀtoꢀaffordꢀ
701,ꢀ 656ꢀ cm ;ꢀ EI‐MSꢀ (m/z,ꢀ relativeꢀ intensity):ꢀ 236ꢀ (M ,ꢀ 90),ꢀ
phenanthrenesꢀ [20,21].ꢀ Weꢀ haveꢀ alsoꢀ demonstratedꢀ thatꢀ theꢀ
introductionꢀ ofꢀ aꢀ suitableꢀ intramolecularꢀ nucleophileꢀ (i.e.,ꢀ anꢀ
217ꢀ(3),ꢀ207ꢀ(5),ꢀ180ꢀ(40),ꢀ165ꢀ(100),ꢀ152ꢀ(10),ꢀ115ꢀ(12),ꢀ83ꢀ
+
(5);ꢀ HRMSꢀ (EI)ꢀ calcd.ꢀ forꢀ C17H17Oꢀ [M+H] :ꢀ 237.1271;ꢀ found:ꢀ
2
–OHꢀorꢀ–NH ꢀgroup)ꢀtoꢀtheꢀsubstrateꢀallowsꢀforꢀtheꢀinitialꢀalleneꢀ
237.1274.ꢀ
productꢀtoꢀundergoꢀaꢀcyclizationꢀtoꢀaffordꢀaꢀbenzofuranꢀorꢀin‐
doleꢀ(Schemeꢀ1(B))ꢀ[22].ꢀAsꢀpartꢀofꢀourꢀongoingꢀinterestꢀinꢀtheꢀ
developmentꢀofꢀnewꢀreactionsꢀforꢀorganicꢀsynthesis,ꢀweꢀreportꢀ
hereinꢀ theꢀ Cu(I)‐catalyzedꢀ cascadeꢀ reactionꢀ ofꢀ
N‐tosylhydrazonesꢀ withꢀ 3‐butyn‐1‐olꢀ (Schemeꢀ 1(C)).ꢀ Notably,ꢀ
thisꢀreactionꢀprovidesꢀfacileꢀaccessꢀtoꢀtetrahydrofuranꢀderiva‐
tives,ꢀwhichꢀareꢀanꢀimportantꢀcompoundsꢀclassꢀwithꢀnumerousꢀ
applicationsꢀacrossꢀvariousꢀareasꢀofꢀresearchꢀ[23–25].ꢀ
2‐(Di‐p‐tolylmethylene)tetrahydrofuranꢀ (3b).ꢀ Waxyꢀ liquid,ꢀ
1
(32ꢀ mg,ꢀ 60%);ꢀ R
NMRꢀ(400ꢀMHz,ꢀCDCl
6H),ꢀ4.22ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀHz,ꢀ2H),ꢀ2.60ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ2.34ꢀ(s,ꢀ3H),ꢀ
f
ꢀ =ꢀ 0.55ꢀ (1:100,ꢀ EtOAc/petroleumꢀ ether);ꢀ Hꢀ
3
)ꢀδꢀ7.27ꢀ(d,ꢀJꢀ=ꢀ8.1ꢀHz,ꢀ2H),ꢀ7.12–7.04ꢀ(m,ꢀ
13
2.29ꢀ(s,ꢀ3H),ꢀ2.02–1.95ꢀ(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl )ꢀδꢀ
3
154.5,ꢀ 139.2,ꢀ 137.3,ꢀ 135.4,ꢀ 134.7,ꢀ 130.2,ꢀ 128.9,ꢀ 128.8,ꢀ 128.4,ꢀ
110.3,ꢀ71.1,ꢀ30.0,ꢀ24.9,ꢀ21.1,ꢀ21.0;ꢀIRꢀ(film):ꢀ2974,ꢀ2918,ꢀ1712,ꢀ
–1
1642,ꢀ 1609,ꢀ 1510,ꢀ 1408,ꢀ 1172,ꢀ 1034,ꢀ 819,ꢀ 665ꢀ cm ;ꢀ EI‐MSꢀ
+
(
m/z,ꢀrelativeꢀintensity):ꢀ264ꢀ(M ,ꢀ100),ꢀ249ꢀ(3),ꢀ235ꢀ(5),ꢀ221ꢀ
2
.ꢀ ꢀ Experimentalꢀ
(8),ꢀ208ꢀ(40),ꢀ193ꢀ(60),ꢀ178ꢀ(38),ꢀ165ꢀ(10),ꢀ152ꢀ(5),ꢀ139ꢀ(3),ꢀ
29ꢀ(8),ꢀ115ꢀ(5),ꢀ89ꢀ(5);ꢀHRMSꢀ(EI)ꢀcalcd.ꢀforꢀC19
21Oꢀ[M+H]+:ꢀ
265.1587;ꢀfound:ꢀ265.1583.ꢀ
‐(Di(thiophen‐3‐yl)methylene)tetrahydrofuranꢀ (3c).ꢀ Lightꢀ
brownꢀliquidꢀ(31ꢀmg,ꢀ63%);ꢀR ꢀ=ꢀ0.50ꢀ(1:100,ꢀEtOAc/petroleumꢀ
ether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl )ꢀδꢀ7.29ꢀ(dd,ꢀJꢀ=ꢀ3.0,ꢀ4.9ꢀHz,ꢀ1H),ꢀ
1
H
2.1.ꢀ ꢀ Generalꢀ
2
Allꢀ ofꢀ theꢀ reactionsꢀ wereꢀ performedꢀ underꢀ nitrogenꢀ inꢀ
f
1
10‐mLꢀ microwaveꢀ tubes.ꢀ Dioxaneꢀ wasꢀ driedꢀ overꢀ Naꢀ metalꢀ
3
beforeꢀ beingꢀ used.ꢀ Columnꢀ chromatographyꢀ wasꢀ performedꢀ
7.24ꢀ(dd,ꢀJꢀ=ꢀ1.2,ꢀ5.0ꢀHz,ꢀ1H),ꢀ7.20–7.17ꢀ(m,ꢀ2H),ꢀ7.08ꢀ(dd,ꢀJꢀ=ꢀ1.2,ꢀ
2.9ꢀHz,ꢀ1H),ꢀ6.97ꢀ(dd,ꢀJꢀ=ꢀ1.1,ꢀ4.9ꢀHz,ꢀ1H),ꢀ4.32ꢀ(t,ꢀJꢀ=ꢀ6.8ꢀHz,ꢀ2H),ꢀ
ꢀ
1
overꢀ 200–300ꢀ meshꢀ silicaꢀ gelꢀ (Qingdao,ꢀ China). Hꢀ NMRꢀ (400ꢀ
MHz)ꢀ andꢀ 13Cꢀ NMRꢀ (100ꢀ MHz)ꢀ spectraꢀ wereꢀ recordedꢀ onꢀ
BruckerꢀARXꢀ400ꢀspectrometer.ꢀChemicalꢀshiftsꢀ()ꢀareꢀreport‐
13
2.62ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ2.02ꢀ(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl
3
)ꢀ
δꢀ155.2,ꢀ141.5,ꢀ140.1,ꢀ129.7,ꢀ128.4,ꢀ124.7,ꢀ123.7,ꢀ123.0,ꢀ120.6,ꢀ

ꢀ
MohammadꢀLokmanꢀHossainꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ115–122ꢀ
117ꢀ
1
1
01.6,ꢀ71.7,ꢀ30.0,ꢀ24.7;ꢀIRꢀ(film):ꢀ2960,ꢀ2924,ꢀ1650,ꢀ1461,ꢀ1377,ꢀ
(25.8ꢀmg,ꢀ50%);ꢀR
NMRꢀ(400ꢀMHz,ꢀCDCl
f
ꢀ=ꢀ0.55ꢀ(1:100,ꢀEtOAc/petroleumꢀether);ꢀ Hꢀ
–1
1260,ꢀ1167,ꢀ1082,ꢀ1035,ꢀ795ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrelativeꢀinten‐
3
)ꢀδꢀ7.23–7.16ꢀ(m,ꢀ2H),ꢀ7.18–7.12ꢀ(m,ꢀ2H),ꢀ
7.04–6.99ꢀ(m,ꢀ3H),ꢀ6.94–6.93ꢀ(d,ꢀJꢀ=ꢀ6.9ꢀHz,ꢀ2H),ꢀ4.24ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀ
+
sity):ꢀ248ꢀ(M ,ꢀ100),ꢀ237ꢀ(5),ꢀ219ꢀ(5),ꢀ207ꢀ(12),ꢀ192ꢀ(70),ꢀ177ꢀ
(
40),ꢀ147ꢀ(15),ꢀ134ꢀ(8),ꢀ89ꢀ(5);ꢀHRMSꢀ(EI)ꢀcalcd.ꢀforꢀC13
2
H13OS ꢀ
Hz,ꢀ2H),ꢀ2.61ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ2.31ꢀ(s,ꢀ3H),ꢀ2.28ꢀ(s,ꢀ3H),ꢀ1.99ꢀ
+
13
[M+H] :ꢀ249.0402;ꢀfound:ꢀ249.0399.ꢀ
3
(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl )ꢀδꢀ155.0,ꢀ142.1,ꢀ140.0,ꢀ137.7,ꢀ
2
‐(Bis(4‐fluorophenyl)methylene)tetrahydrofuranꢀ
Whiteꢀ solidꢀ (38ꢀ mg,ꢀ 70%);ꢀ mpꢀ =ꢀ 87–89ꢀ °C;ꢀ R ꢀ =ꢀ 0.38ꢀ (1:60,ꢀ
EtOAc/petroleumꢀether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl )ꢀδꢀ7.33ꢀ(dd,ꢀ
(3d).ꢀ
129.7,ꢀ128.0,ꢀ127.6,ꢀ127.5,ꢀ126.7,ꢀ126.3,ꢀ110.7,ꢀ71.3,ꢀ30.2,ꢀ25.0,ꢀ
21.6,ꢀ21.5;ꢀIRꢀ(film):ꢀ3030,ꢀ2970,ꢀ2316,ꢀ1642,ꢀ1599,ꢀ1484,ꢀ1246,ꢀ
f
1
–1
3
1164,ꢀ1040,ꢀ784,ꢀ704ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrelativeꢀintensity):ꢀ264ꢀ
+
Jꢀ=ꢀ5.7,ꢀ7.8ꢀHz,ꢀ2H),ꢀ7.13ꢀ(dd,ꢀJꢀ=ꢀ5.6,ꢀ7.6ꢀHz,ꢀ2H),ꢀ7.01ꢀ(t,ꢀJꢀ=ꢀ8.2ꢀ
(M ,ꢀ100),ꢀ231ꢀ(5),ꢀ221ꢀ(10),ꢀ208ꢀ(50),ꢀ193ꢀ(60),ꢀ178ꢀ(50),ꢀ165ꢀ
Hz,ꢀ2H),ꢀ6.93ꢀ(t,ꢀJꢀ=ꢀ8.3ꢀHz,ꢀ2H),ꢀ4.27ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀHz,ꢀ2H),ꢀ2.57ꢀ(t,ꢀJꢀ=ꢀ
(10),ꢀ 152ꢀ (5),ꢀ 129ꢀ (5),ꢀ 115ꢀ (3);ꢀ HRMSꢀ (EI)ꢀ calcd.ꢀ forꢀ C19
[M+H] :ꢀ265.1587;ꢀfound:ꢀ265.1585.ꢀ
H21Oꢀ
13
+
3
7.5ꢀHz,ꢀ2H),ꢀ2.02ꢀ(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl )ꢀδꢀ162.2ꢀ(d,ꢀ
Jꢀ=ꢀ75.3ꢀHz),ꢀ159.8ꢀ(d,ꢀJꢀ=ꢀ75.0ꢀHz),ꢀ155.2,ꢀ137.8ꢀ(d,ꢀJꢀ=ꢀ3.4ꢀHz),ꢀ
2‐(Bis(3‐methoxyphenyl)methylene)tetrahydrofuranꢀ
(3i).ꢀ
1
1
2
8
2
35.8ꢀ(d,ꢀJꢀ=ꢀ3.2ꢀHz),ꢀ131.9ꢀ(d,ꢀJꢀ=ꢀ7.9ꢀHz),ꢀ130.3ꢀ(d,ꢀJꢀ=ꢀ7.5ꢀHz),ꢀ
15.2ꢀ(d,ꢀJꢀ=ꢀ21.2ꢀHz),ꢀ114.5ꢀ(d,ꢀJꢀ=ꢀ21.1ꢀHz),ꢀ108.6,ꢀ71.5,ꢀ30.1,ꢀ
4.9;ꢀIRꢀ(film):ꢀ2969,ꢀ2901,ꢀ1642,ꢀ1603,ꢀ1507,ꢀ1223,ꢀ1033,ꢀ836,ꢀ
00,ꢀ 652ꢀ cm ;ꢀ EI‐MSꢀ (m/z,ꢀ relativeꢀ intensity):ꢀ 272ꢀ (M ,ꢀ 95),ꢀ
43ꢀ(3),ꢀ216ꢀ(50),ꢀ201ꢀ(100),ꢀ183ꢀ(8),ꢀ133ꢀ(4),ꢀ120ꢀ(3),ꢀ101ꢀ(8);ꢀ
Whiteꢀ oilꢀ (34.8ꢀ mg,ꢀ 59%);ꢀ R
ether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl )ꢀδꢀ7.22ꢀ(t,ꢀJꢀ=ꢀ7.9ꢀHz,ꢀ2H),ꢀ7.16ꢀ
(t,ꢀJꢀ=ꢀ7.9ꢀHz,ꢀ2H),ꢀ7.05–7.04ꢀ(m,ꢀ1H),ꢀ 6.95(d,ꢀ Jꢀ=ꢀ7.9ꢀHz,ꢀ1H),ꢀ
6.75–6.79ꢀ(m,ꢀ3H),ꢀ6.88ꢀ(dd,ꢀJꢀ=ꢀ2.0,ꢀ7.9ꢀHz,ꢀ1H),ꢀ4.27ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀ
f
ꢀ =ꢀ 0.40ꢀ (1:40,ꢀ EtOAc/petroleumꢀ
1
3
–1
+
Hz,ꢀ2H),ꢀ3.77ꢀ(s,ꢀ3H),ꢀ3.74ꢀ(m,ꢀ3H),ꢀ2.61ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ2.00ꢀ
+
13
HRMSꢀ (EI)ꢀ calcd.ꢀ forꢀ C17
73.1082.ꢀ
‐(Bis(4‐chlorophenyl)methylene)tetrahydrofuranꢀ
H
15ꢀ
F
2
Oꢀ [M+H] :ꢀ 273.1086;ꢀ found:ꢀ
(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl
3
)ꢀδꢀ159.6,ꢀ159.2,ꢀ155.7,ꢀ143.4,ꢀ
2
141.2,ꢀ 129.2,ꢀ 128.6,ꢀ 123.1,ꢀ 116.1,ꢀ 114.9,ꢀ 111.6,ꢀ 110.6,ꢀ 110.3,ꢀ
71.5,ꢀ55.2,ꢀ55.1,ꢀ30.4,ꢀ24.8;ꢀIRꢀ(film):ꢀ2920,ꢀ2845,ꢀ1643,ꢀ1600,ꢀ
2
(3e).ꢀ
–1
Whiteꢀ waxyꢀ solidꢀ (40ꢀ mg,ꢀ 66%);ꢀ R
f
ꢀ =ꢀ 0.43ꢀ (1:100,ꢀ
1490,ꢀ 1283,ꢀ 1222,ꢀ 1032,ꢀ 876,ꢀ 779ꢀ cm ;ꢀ EI‐MSꢀ (m/z,ꢀ relativeꢀ
EtOAc/petroleumꢀ ether);ꢀ 1Hꢀ NMRꢀ (400ꢀ MHz,ꢀ CDCl
)ꢀ δꢀ
.30–7.28ꢀ(m,ꢀ4H),ꢀ7.20ꢀ(d,ꢀJꢀ=ꢀ8.7ꢀHz,ꢀ2H),ꢀ7.10ꢀ(d,ꢀJꢀ=ꢀ8.5ꢀHz,ꢀ
H),ꢀ4.28ꢀ(t,ꢀJꢀ=ꢀ6.8ꢀHz,ꢀ2H),ꢀ2.58ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ2.06–1.99ꢀ
intensity):ꢀ296ꢀ(M ,ꢀ100),ꢀ281ꢀ(3),ꢀ253ꢀ(3),ꢀ240ꢀ(30),ꢀ225ꢀ(20),ꢀ
+
3
7
2
209ꢀ(20),ꢀ195ꢀ(10),ꢀ181ꢀ(5),ꢀ165ꢀ(5),ꢀ152ꢀ(5),ꢀ139ꢀ(5);ꢀHRMSꢀ
+
(EI)ꢀcalcd.ꢀforꢀC19
H
21
O
3
ꢀ[M+H] :ꢀ297.1485;ꢀfound:ꢀ297.1484.ꢀ
13
(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl
3
)ꢀδꢀ156.1,ꢀ140.1,ꢀ138.0,ꢀ131.8,ꢀ
2‐(Bis(3‐fluorophenyl)methylene)tetrahydrofuranꢀ(3j).ꢀWhiteꢀ
oilꢀ(34.3ꢀmg,ꢀ63%);ꢀRfꢀ=ꢀ0.50ꢀ(1:100,ꢀEtOAc/petroleumꢀether);ꢀ
1
1
30.1,ꢀ 128.6,ꢀ 127.9,ꢀ 108.5,ꢀ 71.6,ꢀ 29.7,ꢀ 24.8;ꢀ IRꢀ (film):ꢀ 2924,ꢀ
642,ꢀ1691,ꢀ1176,ꢀ1091,ꢀ1033,ꢀ907,ꢀ731ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrela‐
–1
1HꢀNMRꢀ(400ꢀMHz,ꢀCDCl
3
)ꢀδꢀ7.31–7.26ꢀ(m,ꢀ1H),ꢀ7.20–7.15ꢀ(m,ꢀ
+
tiveꢀintensity):ꢀ304ꢀ(M ,ꢀ100),ꢀ248ꢀ(50),ꢀ234ꢀ(15),ꢀ213ꢀ(25),ꢀ199ꢀ
2H),ꢀ7.08–7.06ꢀ(m,ꢀ1H),ꢀ6.97–6.88ꢀ(m,ꢀ3H),ꢀ6.84‐6.79ꢀ(m,ꢀ1H),ꢀ
13
(60),ꢀ 178ꢀ (40),ꢀ 163ꢀ (28),ꢀ 149ꢀ (5),ꢀ 137ꢀ (5),ꢀ 125ꢀ (10),ꢀ 99ꢀ (8);ꢀ
4.30ꢀ(t,ꢀJꢀ=ꢀ6.8ꢀHz,ꢀ2H),ꢀ2.60ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ2.03ꢀ(m,ꢀ2H);ꢀ Cꢀ
NMRꢀ(100ꢀMHz,ꢀCDCl )ꢀδꢀ161.9ꢀ(d,ꢀJ ꢀ=ꢀ245.9ꢀHz),ꢀ161.7ꢀ(d,ꢀJ ꢀ=ꢀ
243.4ꢀHz),ꢀ155.8,ꢀ142.7ꢀ(d,ꢀJ ꢀ=ꢀ7.8ꢀHz),ꢀ140.5ꢀ(d,ꢀJ ꢀ=ꢀ8.2ꢀHz),ꢀ
128.7ꢀ(d,ꢀJ ꢀ=ꢀ8.6ꢀHz),ꢀ127.9ꢀ(d,ꢀJ ꢀ=ꢀ8.6ꢀHz),ꢀ125.2ꢀ(d,ꢀJ ꢀ=ꢀ2.7ꢀHz),ꢀ
123.3ꢀ(d,ꢀJ ꢀ=ꢀ2.7ꢀHz),ꢀ116.3ꢀ(d,ꢀJ ꢀ=ꢀ20.6ꢀHz),ꢀ114.5ꢀ(d,ꢀJ ꢀ=ꢀ22.5ꢀ
Hz),ꢀ112.3ꢀ(d,ꢀJ ꢀ=ꢀ20.9ꢀHz),ꢀ111.1ꢀ(d,ꢀJ ꢀ=ꢀ21.4ꢀHz),ꢀ107.8,ꢀ70.8,ꢀ
+
HRMSꢀ (EI)ꢀ calcd.ꢀ forꢀ C17
05.0490.ꢀ
‐(Bis(4‐(trifluoromethyl)phenyl)methylene)tetrahydrofuranꢀ
3f).ꢀ Colorlessꢀ liquidꢀ (46ꢀ mg,ꢀ 62%);ꢀ R ꢀ =ꢀ 0.45ꢀ (1:100,ꢀ
EtOAc/petroleumꢀ ether);ꢀ 1Hꢀ NMRꢀ (400ꢀ MHz,ꢀ CDCl
)ꢀ δꢀ
.53–7.33ꢀ(m,ꢀ8H),ꢀ4.32ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀHz,ꢀ2H),ꢀ2.61ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ
H15ꢀ Cl
2
Oꢀ [M+H] :ꢀ 305.0495;ꢀ found:ꢀ
3
F
F
3
F
F
2
F
F
F
(
f
F
F
F
3
F
F
7
2
1
29.5,ꢀ23.7;ꢀIRꢀ(film):ꢀ2978,ꢀ2344,ꢀ1640,ꢀ1609,ꢀ1580,ꢀ1486,ꢀ1439,ꢀ
13
–1
H),ꢀ2.05ꢀ(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl
40.3,ꢀ133.9,ꢀ132.0,ꢀ129.0,ꢀ128.2,ꢀ127.1ꢀ(q,ꢀJꢀ=ꢀ3.6ꢀHz),ꢀ125.6ꢀ(d,ꢀ
3
)ꢀδꢀ157.6,ꢀ142.1,ꢀ
1183,ꢀ1165,ꢀ1039,ꢀ780,ꢀ744ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrelativeꢀintensi‐
+
ty):ꢀ272ꢀ(M ,ꢀ100),ꢀ253ꢀ(3),ꢀ230ꢀ(10),ꢀ216ꢀ(30),ꢀ201ꢀ(80),ꢀ183ꢀ
Jꢀ=ꢀ3.8ꢀHz),ꢀ123.3ꢀ(d,ꢀJꢀ=ꢀ3.7ꢀHz),ꢀ122.1ꢀ(d,ꢀJꢀ=ꢀ3.7ꢀHz),ꢀ108.4,ꢀ72.0,ꢀ
(10),ꢀ170ꢀ(3),ꢀ133ꢀ(5),ꢀ115ꢀ(5),ꢀ101ꢀ(8);ꢀHRMSꢀ(EI)ꢀcalcd.ꢀforꢀ
+
3
0.5,ꢀ24.7;ꢀIRꢀ(film):ꢀ2951,ꢀ1643,ꢀ1331,ꢀ1280,ꢀ1260,ꢀ1166,ꢀ1123,ꢀ
17 15 2
C H F Oꢀ[M+H] :ꢀ273.1085;ꢀfound:ꢀ273.1085.ꢀ
–1
+
1074ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrelativeꢀintensity):ꢀ372ꢀ(M ,ꢀ100),ꢀ353ꢀ
2‐(Bis(2‐fluorophenyl)methylene)tetrahydrofuranꢀ
(3k).ꢀ
ꢀ=ꢀ0.50ꢀ(1:100,ꢀEtOAc/petroleumꢀ
)ꢀ δꢀ 7.32–7.28ꢀ (m,ꢀ 1H),ꢀ
(
10),ꢀ330ꢀ(5),ꢀ316ꢀ(8),ꢀ302ꢀ(10),ꢀ282ꢀ(5),ꢀ247ꢀ(6),ꢀ233ꢀ(60),ꢀ183ꢀ
Whiteꢀoilꢀ(30.7ꢀmg,ꢀ56%);ꢀR
ether);ꢀ Hꢀ NMRꢀ (400ꢀ MHz,ꢀ CDCl
f
+
1
(
8);ꢀHRMSꢀ(EI)ꢀcalcd.ꢀforꢀC19
73.1017.ꢀ
‐(Bis(4‐methoxyphenyl)methylene)tetrahydrofuranꢀ
15 6
H F Oꢀ[M+H] :ꢀ373.1022;ꢀfound:ꢀ
3
3
7.20–7.16ꢀ(m,ꢀ3H),ꢀ7.14–6.97ꢀ(m,ꢀ4H),ꢀ4.21ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀHz,ꢀ2H),ꢀ
13
2
(3g).ꢀ
2.62ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ2.05ꢀ(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl
3
)ꢀ
Lightꢀ yellowꢀ liquidꢀ (35ꢀ mg,ꢀ 58%);ꢀ R
f
ꢀ =ꢀ 0.40ꢀ (1:30,ꢀ
δꢀ160.4ꢀ(d,ꢀJ
(d,ꢀJ ꢀ=ꢀ3.5ꢀHz),ꢀ132.0ꢀ(d,ꢀJ
128.1ꢀ(d,ꢀJ
Hz),ꢀ123.8ꢀ(d,ꢀJ
23.0ꢀHz),ꢀ115.6ꢀ(d,ꢀJ
3058,ꢀ 2848,ꢀ 1662,ꢀ 1645,ꢀ 1576,ꢀ 1490,ꢀ 1225,ꢀ 1179,ꢀ 991,ꢀ 758ꢀ
F
ꢀ=ꢀ246.1ꢀHz),ꢀ160.1ꢀ(d,ꢀJ
F
ꢀ=ꢀ247.4ꢀHz),ꢀ157.8,ꢀ132.3ꢀ
1
EtOAc/petroleumꢀether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl
3
)ꢀδꢀ7.46ꢀ(d,ꢀJꢀ
ꢀ8.3ꢀHz,ꢀ2H),ꢀ7.32ꢀ(d,ꢀJꢀ=ꢀ8.7ꢀHz,ꢀ2H),ꢀ6.83ꢀ(dd,ꢀJꢀ=ꢀ8.7,ꢀ23.0ꢀHz,ꢀ
H),ꢀ4.24ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀHz,ꢀ2H),ꢀ3.81ꢀ(s,ꢀ3H),ꢀ3.77ꢀ(s,ꢀ3H),ꢀ2.59ꢀ(t,ꢀJꢀ=ꢀ
.5ꢀ Hz,ꢀ 2H),ꢀ 2.60–1.96ꢀ (m,ꢀ 2H);ꢀ Cꢀ NMRꢀ (100ꢀ MHz,ꢀ CDCl
57.8,ꢀ 157.1,ꢀ 144.5,ꢀ 142.0,ꢀ 136.5,ꢀ 131.4,ꢀ 130.2,ꢀ 130.0,ꢀ 129.3,ꢀ
27.6,ꢀ124.6,ꢀ113.6,ꢀ113.2,ꢀ71.1,ꢀ55.2,ꢀ29.9,ꢀ25.0,ꢀ21.6,ꢀ21.4;ꢀIRꢀ
F
F
ꢀ=ꢀ3.9ꢀHz),ꢀ128.5ꢀ(d,ꢀJ
F
ꢀ=ꢀ15.6ꢀHz),ꢀ
ꢀ=ꢀ15.4ꢀ
ꢀ=ꢀ3.3ꢀHz),ꢀ115.7ꢀ(d,ꢀJ ꢀ=ꢀ
ꢀ=ꢀ22.5ꢀHz),ꢀ97.9,ꢀ71.9,ꢀ28.9,ꢀ24.9;ꢀIRꢀ(film):ꢀ
=
4
7
1
1
F
F
ꢀ=ꢀ8.2ꢀHz),ꢀ127.9ꢀ(d,ꢀJ ꢀ=ꢀ8.3ꢀHz),ꢀ127.3ꢀ(d,ꢀJ
F
F
ꢀ=ꢀ3.4ꢀHz),ꢀ123.6ꢀ(d,ꢀJ
F
F
13
3
)ꢀ δꢀ
F
–
1
+
cm ;ꢀ EI‐MSꢀ (m/z,ꢀ relativeꢀ intensity):ꢀ 272ꢀ (M ,ꢀ 100),ꢀ 253ꢀ (1),ꢀ
243ꢀ(3),ꢀ240ꢀ(20),ꢀ216ꢀ(40),ꢀ201ꢀ(90),ꢀ183ꢀ(20),ꢀ170ꢀ(2),ꢀ133ꢀ
–1
(
film):ꢀ 2925,ꢀ 2853,ꢀ 1608,ꢀ 1509,ꢀ 1246,ꢀ 1173,ꢀ 1033,ꢀ 653ꢀ cm ;ꢀ
+
+
EI‐MSꢀ (m/z,ꢀ relativeꢀ intensity):ꢀ 296ꢀ (M ,ꢀ 100),ꢀ 281ꢀ (10),ꢀ 267ꢀ
(5),ꢀ101ꢀ(5);ꢀHRMSꢀ(EI)ꢀcalcd.ꢀforꢀC19
H
15
F
2
Oꢀ[M+H] :ꢀ273.1085;ꢀ
(
10),ꢀ253ꢀ(12),ꢀ240ꢀ(75),ꢀ225ꢀ(40),ꢀ207ꢀ(45),ꢀ165ꢀ(15),ꢀ113(20);ꢀ
found:ꢀ273.1083.ꢀ
+
HRMSꢀ (EI)ꢀ calcd.ꢀ forꢀ C19
97.1490.ꢀ
‐(Di‐m‐tolylmethylene)tetrahydrofuranꢀ (3h).ꢀ Whiteꢀ oilꢀ
21 3
H O ꢀ [M+H] ꢀ 297.1485;ꢀ found:ꢀ
2
2.3.ꢀ ꢀ GeneralꢀprocedureꢀforꢀtheꢀCu(I)‐catalyzedꢀreactionꢀofꢀ
N‐tosylhydrazonesꢀ4a–cꢀwithꢀ3‐butyn‐1‐olꢀ ꢀ
2

118ꢀ
MohammadꢀLokmanꢀHossainꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ115–122ꢀ
3
‐Butyn‐1‐olꢀ(2,ꢀ42ꢀmg,ꢀ0.6ꢀmmol)ꢀwasꢀaddedꢀtoꢀaꢀmixtureꢀofꢀ
(1ꢀmL)ꢀunderꢀnitrogen,ꢀandꢀtheꢀresultingꢀmixtureꢀwasꢀstirredꢀatꢀ
110ꢀ°Cꢀforꢀ4ꢀh.ꢀUponꢀcompletionꢀofꢀtheꢀreaction,ꢀasꢀdeterminedꢀ
byꢀTLCꢀanalysis,ꢀtheꢀmixtureꢀwasꢀcooledꢀtoꢀroomꢀtemperatureꢀ
andꢀ treatedꢀ withꢀ TsOHꢀ (103.2ꢀ mg,ꢀ 0.6ꢀ mmol)ꢀ beforeꢀ beingꢀ
heatedꢀatꢀ70ꢀ°Cꢀforꢀ2ꢀh.ꢀTheꢀmixtureꢀwasꢀthenꢀcooledꢀtoꢀroomꢀ
temperatureꢀ andꢀ evaporatedꢀ underꢀ vacuumꢀ toꢀ giveꢀ aꢀ crudeꢀ
mixture,ꢀwhichꢀwasꢀpurifiedꢀbyꢀcolumnꢀchromatographyꢀoverꢀ
silicaꢀgelꢀtoꢀaffordꢀpureꢀ8aꢀasꢀaꢀcolorlessꢀliquidꢀ(43ꢀmg,ꢀ63%).ꢀ
(E)‐2‐(4‐(Trifluoromethyl)benzylidene)tetrahydrofuranꢀ (8a).ꢀ
CuIꢀ(3.8ꢀmg,ꢀ0.02ꢀmmol),ꢀbathophenanthrolineꢀ(6.64ꢀmg,ꢀ0.02ꢀ
mmol),ꢀTBABꢀ(19.3ꢀmg,ꢀ0.06ꢀmmol),ꢀLiO Buꢀ(48ꢀmg,ꢀ0.ꢀ6ꢀmmol)ꢀ
andꢀN‐tosylhydrazoneꢀ(4a,ꢀ85.3ꢀmg,ꢀ0.2ꢀmmol)ꢀinꢀ1,4‐dioxaneꢀ
1ꢀmL)ꢀunderꢀnitrogen,ꢀandꢀtheꢀresultingꢀmixtureꢀwasꢀstirredꢀatꢀ
t
(
1
10ꢀ°Cꢀforꢀ4ꢀh.ꢀUponꢀcompletionꢀofꢀtheꢀreaction,ꢀasꢀdeterminedꢀ
byꢀTLCꢀanalysis,ꢀtheꢀmixtureꢀwasꢀcooledꢀtoꢀroomꢀtemperatureꢀ
andꢀtreatedꢀwithꢀTsOHꢀ(68.8ꢀmg,ꢀ0.4ꢀmmol),ꢀandꢀtheꢀresultingꢀ
mixtureꢀ wasꢀ stirredꢀ atꢀ 80ꢀ °Cꢀ forꢀ 2ꢀ h.ꢀ Theꢀ mixtureꢀ wasꢀ thenꢀ
cooledꢀtoꢀambientꢀtemperatureꢀandꢀevaporatedꢀunderꢀvacuumꢀ
toꢀgiveꢀaꢀcrudeꢀresidue,ꢀwhichꢀwasꢀpurifiedꢀbyꢀcolumnꢀchroma‐
tographyꢀoverꢀsilicaꢀgelꢀtoꢀaffordꢀpureꢀ5aꢀasꢀwhiteꢀsolidꢀ(42ꢀmg,ꢀ
Colorlessꢀ liquidꢀ (43ꢀ mg,ꢀ 63%);ꢀ
EtOAc/petroleumꢀether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl
R
f
ꢀ
=ꢀ 0.42ꢀ (1:50,ꢀ
)ꢀδꢀ7.50ꢀ(d,ꢀJꢀ
1
3
=ꢀ8.1ꢀHz,ꢀ2H),ꢀ7.24ꢀ(d,ꢀJꢀ=ꢀ10.0ꢀHz,ꢀ2H),ꢀ5.93ꢀ(s,ꢀ1H),ꢀ4.16ꢀ(t,ꢀJꢀ=ꢀ
ꢀ13
6
7%).ꢀ
6.8ꢀHz,ꢀ2H),ꢀ2.84ꢀ(t,ꢀJꢀ=ꢀ7.4ꢀHz,ꢀ2H),ꢀ2.17‐2.10ꢀ(m,ꢀ2H); CꢀNMRꢀ
(100ꢀ MHz,ꢀ CDCl )ꢀ δꢀ 161.3,ꢀ 141.6,ꢀ 129.8,ꢀ 125.2ꢀ (q,ꢀ Jꢀ =ꢀ 3.8ꢀ Hz,ꢀ
CF ),ꢀ 98.3,ꢀ 69.8,ꢀ 28.7,ꢀ 25.1;ꢀ IRꢀ (film)ꢀ 2931,ꢀ 1653,ꢀ 1371,ꢀ 1180,ꢀ
(E)‐2‐([1,1'‐Biphenyl]‐4‐yl(phenyl)methylene)tetrahydrofuranꢀ
3
(
(
5a).ꢀ Whiteꢀ solidꢀ (42ꢀ mg,ꢀ 67%);ꢀ mpꢀ =ꢀ 141–142ꢀ °C;ꢀ R
1:200,ꢀEtOAc/petroleumꢀether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl
f
ꢀ=ꢀ 0.45ꢀ
3
1
–1
+
3
)ꢀδꢀ
1123,ꢀ1084ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrelativeꢀintensity):ꢀ228ꢀ(M ,ꢀ95),ꢀ
7
4
.62ꢀ(d,ꢀJꢀ=ꢀ7.6ꢀHz,ꢀ2H),ꢀ7.55ꢀ(d,ꢀJꢀ=ꢀ8.3ꢀHz,ꢀ2H),ꢀ7.45–7.41ꢀ(m,ꢀ
H),ꢀ7.27–7.25ꢀ(m,ꢀ4H),ꢀ7.13ꢀ(t,ꢀJꢀ=ꢀ7.3ꢀHz,ꢀ1H),ꢀ4.27ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀ
209ꢀ (20),ꢀ 186ꢀ (100),ꢀ 158ꢀ (85),ꢀ 138ꢀ (18),ꢀ 89ꢀ (15);ꢀ HRMSꢀ (EI)ꢀ
+
12 3
calcd.ꢀforꢀC12H F Oꢀ[M+H] ꢀ229.0835;ꢀfound:ꢀ229.0837.ꢀ
13
Hz,ꢀ 2H),ꢀ 2.70ꢀ (t,ꢀ Jꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ2.04ꢀ(m,ꢀ2H);ꢀ Cꢀ NMRꢀ (100ꢀ
MHz,ꢀ CDCl )ꢀδꢀ 155.6,ꢀ 141.9,ꢀ 141.2,ꢀ139.1,ꢀ137.8,ꢀ 130.6,ꢀ129.2,ꢀ
28.6,ꢀ 128.3,ꢀ 126.9,ꢀ 126.4,ꢀ 126.1,ꢀ 110.2,ꢀ 71.5,ꢀ 30.3,ꢀ 24.8;ꢀ IRꢀ
film):ꢀ3051,ꢀ2927,ꢀ1631,ꢀ1596,ꢀ1489,ꢀ1442,ꢀ1260,ꢀ1171,ꢀ1033,ꢀ
(E)‐4‐((Dihydrofuran‐2(3H)‐ylidene)methyl)benzonitrileꢀ (8b).ꢀ
3
Colorlessꢀ liquidꢀ (39ꢀ mg,ꢀ 70%);ꢀ
EtOAc/petroleumꢀether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl
R
f
ꢀ
=ꢀ 0.35ꢀ (1:30,ꢀ
)ꢀδꢀ7.52ꢀ(d,ꢀJꢀ
1
1
(
3
=ꢀ8.4ꢀHz,ꢀ2H),ꢀ7.21ꢀ(d,ꢀJꢀ=ꢀ8.4ꢀHz,ꢀ2H),ꢀ5.90ꢀ(s,ꢀ1H),ꢀ4.18ꢀ(t,ꢀJꢀ=ꢀ6.9ꢀ
–1
+
13
7
2
C
65,ꢀ692ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrelativeꢀintensity):ꢀ312ꢀ(M ,ꢀ100),ꢀ
56ꢀ (40),ꢀ 241ꢀ (38),ꢀ 165ꢀ (20),ꢀ 121ꢀ (25);ꢀ HRMSꢀ (EI)ꢀ calcd.ꢀ forꢀ
Hz,ꢀ 2H),ꢀ 2.85ꢀ (dt,ꢀ Jꢀ =ꢀ 1.9,ꢀ 7.6ꢀ Hz,ꢀ 2H),ꢀ 2.15ꢀ (m,ꢀ 2H);ꢀ Cꢀ NMRꢀ
3
(100ꢀ MHz,ꢀ CDCl )ꢀ δꢀ 162.7,ꢀ 142.9,ꢀ 132.1,ꢀ 126.9,ꢀ 119.5,ꢀ 107.1,ꢀ
+
23
H
21Oꢀ[M+H] ꢀ313.1587;ꢀfound:ꢀ313.1588.ꢀ
98.6,ꢀ70.0,ꢀ29.0,ꢀ25.1;ꢀIRꢀ(film):ꢀ2924,ꢀ2854,ꢀ2219,ꢀ1708,ꢀ1661,ꢀ
–1
(E)‐2‐((3,4‐Dimethylphenyl)(phenyl)methylene)tetrahydrofuranꢀ
1602,ꢀ1392,ꢀ1173,ꢀ1028,ꢀ984,ꢀ845,ꢀ734ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrela‐
+
(5b).ꢀ Whiteꢀ solidꢀ (38ꢀ mg,ꢀ 72%);ꢀ mpꢀ =ꢀ 90–91ꢀ °C;ꢀ R
f
ꢀ =ꢀ 0.46ꢀ
tiveꢀintensity):ꢀ185ꢀ(M ,ꢀ90),ꢀ177ꢀ(2),ꢀ143ꢀ(100),ꢀ129ꢀ(15),ꢀ115ꢀ
1
(75),ꢀ102ꢀ(5),ꢀ88ꢀ(10);ꢀHRMSꢀ(EI)ꢀcalcd.ꢀforꢀC12H
12NOꢀ[M+H]+ꢀ
186.0913;ꢀfound:ꢀ186.0916.ꢀ
(1:200,ꢀEtOAc/petroleumꢀether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl
3
)ꢀδꢀ
7.39ꢀ(d,ꢀJꢀ=ꢀ7.6ꢀHz,ꢀ2H),ꢀ7.24ꢀ(dd,ꢀJꢀ=ꢀ6.3,ꢀ9.0ꢀHz,ꢀ2H),ꢀ7.12–7.07ꢀ
(
m,ꢀ2H),ꢀ6.96‐6.93ꢀ(m,ꢀ2H),ꢀ4.25ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀHz,ꢀ2H),ꢀ2.62ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀ
(E)‐2‐(2‐Chloro‐4‐(trifluoromethyl)benzylidene)tetrahydrofuranꢀ
(8c).ꢀ Colorlessꢀ liquidꢀ (46ꢀ mg,ꢀ 58%);ꢀ R ꢀ =ꢀ 0.40ꢀ (1:40,ꢀ
EtOAc/petroleumꢀether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl )ꢀδꢀ7.49ꢀ(d,ꢀJꢀ
=ꢀ1.4ꢀHz,ꢀ1H),ꢀ7.44ꢀ(d,ꢀJꢀ=ꢀ8.3ꢀHz,ꢀ1H),ꢀ7.28ꢀ(dd,ꢀJꢀ=ꢀ1.8,ꢀ8.4ꢀHz,ꢀ
1H),ꢀ6.13ꢀ(s,ꢀ1H),ꢀ4.20ꢀ(t,ꢀJꢀ=ꢀ6.8ꢀHz,ꢀ2H),ꢀ2.79ꢀ(dt,ꢀJꢀ=ꢀ1.9,ꢀ7.5ꢀHz,ꢀ
ꢀ13
Hz,ꢀ2H),ꢀ2.26ꢀ(s,ꢀ3H),ꢀ2.22ꢀ(s,ꢀ3H),ꢀ2.03‐1.96ꢀ(m,ꢀ2H); CꢀNMRꢀ
100ꢀ MHz,ꢀ CDCl )ꢀ δꢀ 154.9,ꢀ 140.2,ꢀ 139.5,ꢀ 136.2,ꢀ 134.2,ꢀ 131.6,ꢀ
29.4,ꢀ128.9,ꢀ127.9,ꢀ127.7,ꢀ125.1,ꢀ110.4,ꢀ110.2,ꢀ71.3,ꢀ30.2,ꢀ24.9,ꢀ
9.8,ꢀ19.4;ꢀIRꢀ(film):ꢀ3018,ꢀ2920,ꢀ1641,ꢀ1503,ꢀ1443,ꢀ1171,ꢀ1039,ꢀ
f
1
(
3
3
1
1
8
2
–1
+
13
19,ꢀ701,ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrelativeꢀintensity):ꢀ264ꢀ(M ,ꢀ100),ꢀ
2H),ꢀ2.13ꢀ(m,ꢀ2H);ꢀ CꢀNMRꢀ(100ꢀMHz,ꢀCDCl
3
)ꢀδꢀ162.2,ꢀ136.8,ꢀ
49ꢀ(6),ꢀ221ꢀ(10),ꢀ207ꢀ(60),ꢀ193ꢀ(45),ꢀ178ꢀ(40),ꢀ165ꢀ(12),ꢀ96ꢀ
129.8,ꢀ124.5ꢀ(q,ꢀJꢀ=ꢀ3.9ꢀHz),ꢀ122.3ꢀ(dd,ꢀJꢀ=ꢀ3.8,ꢀ7.6ꢀHz),ꢀ95.1,ꢀ70.2,ꢀ
28.4,ꢀ25.1;ꢀIRꢀ(film):ꢀ2923,ꢀ2854,ꢀ1660,ꢀ1605,ꢀ1417,ꢀ1328,ꢀ1168,ꢀ
+
(20);ꢀ HRMSꢀ (EI)ꢀ calcd.ꢀ forꢀ C19
H
21Oꢀ [M+H] ꢀ 265.1587;ꢀ found:ꢀ
–1
+
2
65.1589.ꢀ
E)‐2‐((4‐Chlorophenyl)(phenyl)methylene)tetrahydrofuranꢀ
5c).ꢀ Whiteꢀ solidꢀ (37ꢀ mg,ꢀ 68%);ꢀ mpꢀ =ꢀ 107–108ꢀ °C;ꢀR ꢀ=ꢀ 0.43ꢀ
1:100,ꢀEtOAc/petroleumꢀether);ꢀ HꢀNMRꢀ(400ꢀMHz,ꢀCDCl )ꢀδꢀ
.35ꢀ(d,ꢀJꢀ=ꢀ7.4ꢀHz,ꢀ2H),ꢀ7.29–7.23ꢀ(m,ꢀ4H),ꢀ7.12ꢀ(d,ꢀJꢀ=ꢀ8.4ꢀHz,ꢀ
H),ꢀ4.26ꢀ(t,ꢀJꢀ=ꢀ6.7ꢀHz,ꢀ2H),ꢀ2.60ꢀ(t,ꢀJꢀ=ꢀ7.5ꢀHz,ꢀ2H),ꢀ2.02ꢀ(m,ꢀ2H);ꢀ
)ꢀδꢀ154.5,ꢀ139.6,ꢀ138.6,ꢀ130.8,ꢀ127.9,ꢀ
27.4,ꢀ 126.8,ꢀ 124.5,ꢀ 108.6,ꢀ 70.4,ꢀ 29.2,ꢀ 23.9;ꢀ IRꢀ (film):ꢀ 2960,ꢀ
887,ꢀ 1642,ꢀ 1596,ꢀ 1490,ꢀ 1259,ꢀ 1089,ꢀ 1031,ꢀ 1015,ꢀ 920,ꢀ 767ꢀ
1129,ꢀ1083ꢀcm ;ꢀEI‐MSꢀ(m/z,ꢀrelativeꢀintensity):ꢀ262ꢀ(M ,ꢀ80),ꢀ
(
243ꢀ (20),ꢀ 220ꢀ (100),ꢀ 192ꢀ (60),ꢀ 157ꢀ (40),ꢀ 138ꢀ (18),ꢀ 87ꢀ (13);ꢀ
+
(
(
7
3
f
HRMSꢀ (EI)ꢀ calcd.ꢀ forꢀ C12
H
11ClF
3
Oꢀ [M+H] ꢀ 263.0448;ꢀ found:ꢀ
1
3
263.0445.ꢀ
3.ꢀ ꢀ Resultsꢀandꢀdiscussionꢀ
13CꢀNMRꢀ(100ꢀMHz,ꢀCDCl
1
2
3
Theꢀ symmetricalꢀ N‐tosylhydrazoneꢀ 1a,ꢀ whichꢀ wasꢀ derivedꢀ
fromꢀ benzophenoneꢀ andꢀ 3‐butyn‐1‐olꢀ (2),ꢀ wasꢀ selectedꢀ asꢀ aꢀ
modelꢀsubstrateꢀforꢀthisꢀreactionꢀwithꢀcopper(I)ꢀiodideꢀasꢀtheꢀ
catalyst.ꢀUnderꢀsimilarꢀreactionꢀconditionsꢀtoꢀthoseꢀpreviouslyꢀ
reportedꢀbyꢀourꢀgroupꢀforꢀtheꢀCu(I)‐catalyzedꢀcross‐couplingꢀofꢀ
N‐tosylhydrazonesꢀ withꢀ alkynesꢀ [9,10,21,22],ꢀ theꢀ reactionꢀ af‐
fordedꢀanꢀisomericꢀmixtureꢀofꢀtheꢀtetrahydrofuranꢀproductꢀ3aꢀ
andꢀdihydrofuranꢀ3a'ꢀ(Tableꢀ1,ꢀentryꢀ1).ꢀTheꢀstructuresꢀofꢀ3aꢀ
andꢀ3a'ꢀwereꢀestablishedꢀbasedꢀonꢀtheirꢀNMRꢀandꢀMSꢀdata.ꢀTheꢀ
structureꢀofꢀ3aꢀwasꢀfurtherꢀconfirmedꢀbyꢀX‐rayꢀcrystallographyꢀ
(Fig.ꢀ1)ꢀ[26].ꢀInꢀthisꢀexperiment,ꢀweꢀalsoꢀobservedꢀaꢀveryꢀsmallꢀ
amountꢀofꢀtheꢀcorrespondingꢀallene,ꢀtheꢀstructureꢀofꢀwhichꢀwasꢀ
–1
+
cm ;ꢀEI‐MSꢀ(m/z,ꢀrelativeꢀintensity):ꢀ270ꢀ(M ,ꢀ100),ꢀ214ꢀ(35),ꢀ
2
00ꢀ(15),ꢀ179ꢀ(50),ꢀ165ꢀ(80),ꢀ139ꢀ(5),ꢀ115ꢀ(5),ꢀ82ꢀ(6);ꢀHRMSꢀ
+
(EI)ꢀcalcd.ꢀforꢀC17
H
16ClOꢀ[M+H] ꢀ271.0884;ꢀfound:ꢀ271.0886.ꢀ
2
.4.ꢀ ꢀ GeneralꢀprocedureꢀforꢀtheꢀCu(I)‐catalyzedꢀreactionꢀofꢀ
N‐tosylhydrazonesꢀ7a–cꢀandꢀ3‐butyn‐1‐olꢀ ꢀ
3‐Butyn‐1‐olꢀ(2,ꢀ63ꢀmg,ꢀ0.9ꢀmmol)ꢀwasꢀaddedꢀtoꢀaꢀmixtureꢀofꢀ
CuIꢀ(5.7ꢀmg,ꢀ0.03ꢀmmol),ꢀbathophenanthrolineꢀ(9.96ꢀmg,ꢀ0.03ꢀ
mmol),ꢀTBABꢀ(28.98ꢀmg,ꢀ0.09ꢀmmol),ꢀLi OBuꢀ(72ꢀmg,ꢀ0.9ꢀmmol)ꢀ
andꢀN‐tosylhydrazoneꢀ(7a,ꢀ68.4ꢀmg,ꢀ0.3ꢀmmol)ꢀinꢀ1,4‐dioxaneꢀ
t
1
13
confirmedꢀbyꢀ Hꢀandꢀ CꢀNMRꢀspectroscopy.ꢀAꢀseriesꢀofꢀscreen‐

ꢀ
MohammadꢀLokmanꢀHossainꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ115–122ꢀ
119ꢀ
TBABꢀgaveꢀtheꢀhighestꢀyieldꢀofꢀtheꢀdesiredꢀproduct.ꢀ
Tableꢀ1ꢀ
Optimizationꢀofꢀtheꢀreactionꢀconditions.ꢀ
Followingꢀonꢀfromꢀtheseꢀpreliminaryꢀresults,ꢀweꢀproceededꢀ
toꢀscreenꢀseveralꢀotherꢀimportantꢀparametersꢀwithꢀtheꢀaimꢀofꢀ
furtherꢀ improvingꢀ theꢀ yieldꢀ andꢀ theꢀ chemoselectivityꢀ ofꢀ thisꢀ
reaction.ꢀWeꢀinitiallyꢀevaluatedꢀaꢀseriesꢀofꢀdifferentꢀCuꢀcatalystsꢀ
usingꢀ phenanthrolineꢀ asꢀ aꢀ ligandꢀ (Tableꢀ 1,ꢀ entriesꢀ 5–9).ꢀ Theꢀ
resultsꢀrevealedꢀthatꢀtheꢀuseꢀofꢀtheꢀCuIꢀcatalystꢀinꢀcombinationꢀ
withꢀphenanthrolineꢀresultedꢀinꢀimprovedꢀperformanceꢀ(Tableꢀ
Entryꢀ Cu(I)/Lꢀ(10ꢀmol%)ꢀ Solvent [O]ꢀorꢀacidꢀ T/ꢀ°Cꢀ
Yieldꢀaꢀ
1
,ꢀentriesꢀ2ꢀandꢀ9).ꢀHowever,ꢀtheꢀnatureꢀofꢀtheꢀcatalystꢀdidꢀnotꢀ
1
ꢀ
CuIꢀ
Dioxane
Dioxane
Toluene
DCEꢀ
—ꢀ
—ꢀ
—ꢀ
—ꢀ
—ꢀ
—ꢀ
—ꢀ
—ꢀ
—ꢀ
90ꢀ 3a+3a',ꢀ45%
90ꢀ 3a+3a',ꢀ57%
90ꢀ 3a+3a',ꢀ30%
90ꢀ 3a+3a',ꢀ25%
90ꢀ 3a+3a',ꢀ38%
90ꢀ 3a+3a',ꢀ10%
90ꢀ 3a+3a',ꢀ8%
90ꢀ 3a+3a',ꢀ35%
110ꢀ 3a+3a',ꢀ64%
110ꢀ Decomposed
110ꢀ Decomposed
appearꢀtoꢀhaveꢀanꢀadverseꢀimpactꢀonꢀtheꢀratioꢀofꢀ3aꢀandꢀ3a'.ꢀ
Weꢀ thereforeꢀ decidedꢀ toꢀ convertꢀ theꢀ isomericꢀ mixtureꢀ gener‐
atedꢀ fromꢀ theꢀ Cu(I)‐catalyzedꢀ couplingꢀ reactionꢀ intoꢀ aꢀ singleꢀ
productꢀ usingꢀ eitherꢀ anꢀ oxidationꢀ orꢀ anꢀ acid‐promotedꢀ rear‐
rangement.ꢀ However,ꢀ inꢀ theꢀ presenceꢀ ofꢀ anꢀ oxidantꢀ suchꢀ asꢀ
2
ꢀ
CuI/phenꢀ
CuI/phenꢀ
CuI/phenꢀ
3
ꢀ
4
ꢀ
5
ꢀ
Cu(MeCN)
Cu(OAc)
Cu(OEt)
4
PF
/phenꢀ
/phenꢀ
6
/phenꢀ Dioxane
6
ꢀ
2
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
Dioxane
7
ꢀ
2
2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinoneꢀ
(DDQ),ꢀ
8
ꢀ
CuCl/phenꢀ
CuI/phenꢀ
CuI/phenꢀ
CuI/phenꢀ
CuI/phenꢀ
CuI/phenꢀ
CuI/phenꢀ
CuI/bathophenꢀ
1,4‐benzoquinoneꢀ (BQ)ꢀ orꢀ PhI(OAc)
2
,ꢀ theꢀ isomericꢀ mixtureꢀ
9
ꢀ
decomposedꢀ toꢀ formꢀ aꢀ complexꢀ mixtureꢀ (Tableꢀ 1,ꢀ entriesꢀ 10ꢀ
andꢀ 11).ꢀ Pleasingly,ꢀ theꢀ treatmentꢀ ofꢀ theꢀ completedꢀ
Cu(I)‐catalyzedꢀreactionꢀmixtureꢀwithꢀ2ꢀequiv.ꢀofꢀTsOHꢀorꢀtri‐
fluoroaceticꢀacidꢀ(TFA)ꢀforꢀ2ꢀhꢀatꢀ80ꢀ°Cꢀaffordedꢀ3aꢀasꢀaꢀsingleꢀ
productꢀinꢀmoderateꢀyieldꢀ(Tableꢀ1,ꢀentriesꢀ12–14).ꢀBasedꢀonꢀ
theseꢀresults,ꢀweꢀscreenedꢀseveralꢀotherꢀreactionꢀparameters,ꢀ
includingꢀ theꢀ reactionꢀ temperature,ꢀ reactionꢀ timeꢀ andꢀ molarꢀ
ratioꢀofꢀtheꢀsubstrates.ꢀFinally,ꢀweꢀconcludedꢀthatꢀtheꢀoptimumꢀ
conditionsꢀ forꢀ thisꢀ transformationꢀ wereꢀ asꢀ follows:ꢀ 1:3ꢀ
10ꢀ
11ꢀ
12ꢀ
13ꢀ
14ꢀ
15ꢀ
BQꢀ
DDQꢀ
TsOHꢀ
TsOHꢀ
TFAꢀ
TsOHꢀ
90ꢀ
3a,ꢀ59%ꢀ
110ꢀ 3a,ꢀ68%ꢀ
110ꢀ 3a,ꢀ66%ꢀ
110ꢀ 3a,ꢀ75%ꢀ
Reactionꢀconditions:ꢀForꢀstepꢀ1,ꢀ1aꢀ(0.2ꢀmmol),ꢀ2ꢀ(3.0ꢀequiv.),ꢀCu(I)ꢀ(10ꢀ
mol%),ꢀphenꢀorꢀbathophenꢀ(10ꢀmol%),ꢀTBABꢀ(30ꢀmol%)ꢀandꢀbaseꢀ(3.0ꢀ
equiv.)ꢀinꢀdioxaneꢀ(1ꢀmL)ꢀatꢀ90–110ꢀ°Cꢀforꢀ4ꢀh.ꢀForꢀstepꢀ2,ꢀ[O]ꢀorꢀTsOHꢀ
(
ꢀ
2.0ꢀequiv)ꢀatꢀ70–80ꢀ°Cꢀforꢀ2ꢀh.ꢀ
Isolatedꢀyieldꢀafterꢀcolumnꢀchromatography.ꢀ
a
(mol/mol)ꢀratioꢀofꢀN‐tosylhydrazoneꢀ1aꢀandꢀ3‐butyn‐1‐olꢀ(2),ꢀ
1
0ꢀmol%ꢀCuI,ꢀ10ꢀmol%ꢀbathophenanthroline,ꢀ30ꢀmol%ꢀTBABꢀ
Phen:ꢀ
ꢀ
,ꢀBathophen:ꢀ
andꢀ3.0ꢀequiv.ꢀofꢀLiO Buꢀatꢀ110ꢀ°Cꢀ(Tableꢀ1,ꢀentryꢀ15).ꢀ
t
Withꢀ theꢀ optimumꢀ reactionꢀ conditionsꢀ inꢀ hand,ꢀ weꢀ pro‐
ceededꢀtoꢀinvestigateꢀtheꢀscopeꢀandꢀgeneralityꢀofꢀthisꢀreactionꢀ
byꢀ screeningꢀ aꢀ varietyꢀ ofꢀ N‐tosylhydrazonesꢀ (1a–k),ꢀ whichꢀ
wereꢀ derivedꢀ fromꢀ theꢀ correspondingꢀ symmetricalꢀ diaryl‐
methanones,ꢀ withꢀ 3‐butyn‐1‐olꢀ (2).ꢀ Asꢀ shownꢀ inꢀ Schemeꢀ 2,ꢀ
Fig.ꢀ1.ꢀX‐rayꢀstructureꢀofꢀ3a.ꢀThermalꢀellipsoidsꢀshownꢀatꢀ30%ꢀproba‐
bility.ꢀ
ingꢀ experimentsꢀ wereꢀ performedꢀ toꢀ determineꢀ theꢀ optimumꢀ
solventꢀ forꢀ thisꢀ transformation,ꢀ andꢀ theꢀ resultsꢀ revealedꢀ thatꢀ
theꢀpolarꢀaproticꢀsolventꢀdioxaneꢀgaveꢀtheꢀbestꢀresultsꢀ(Tableꢀ1,ꢀ
entriesꢀ3ꢀandꢀ4).ꢀWeꢀalsoꢀtestedꢀvariousꢀbases,ꢀincludingꢀK
2
CO
3
,ꢀ
Schemeꢀ 2.ꢀ Evaluationꢀ ofꢀ theꢀ substrateꢀ scopeꢀ ofꢀ N‐tosylhydrazonesꢀ
derivedꢀ fromꢀ symmetricalꢀ diarylmethanones. Reactionꢀ conditions:ꢀ
N‐tosylhydrazoneꢀ1a–kꢀ(0.2ꢀmmol),ꢀ3‐butyn‐1‐olꢀ(2,ꢀ3.0ꢀequiv.),ꢀCuIꢀ(10ꢀ
ꢀ
t
2 3
Cs CO3,ꢀNaOH,ꢀKOH,ꢀNaH,ꢀLiO BuꢀandꢀNaOCH ,ꢀasꢀwellꢀasꢀseveralꢀ
phaseꢀtransferꢀcatalystsꢀ(PTCs),ꢀincludingꢀtetrabutylammoniumꢀ
bromideꢀ (TBAB),ꢀ tetrabutylammoniumꢀ chlorideꢀ (TBAC)ꢀ andꢀ
tetrabutylammoniumꢀ iodideꢀ (TBAI).ꢀ Theꢀ resultsꢀ ofꢀ theseꢀ ex‐
mol%),ꢀ bathophenanthrolineꢀ (L)ꢀ (10ꢀ mol%),ꢀ TBABꢀ (30ꢀ mol%)ꢀ andꢀ
t
LiO Buꢀ(3.0ꢀequiv.)ꢀinꢀdioxaneꢀ(1ꢀmL)ꢀatꢀ110ꢀ°Cꢀforꢀ4ꢀh.ꢀTsOHꢀ(2.0ꢀequiv.
wasꢀthenꢀadded,ꢀandꢀtheꢀresultingꢀmixtureꢀwasꢀheatedꢀatꢀ80ꢀ°Cꢀforꢀ2ꢀh.ꢀ
Isolatedꢀyieldꢀbyꢀcolumnꢀchromatography.ꢀ
t
perimentsꢀrevealedꢀthatꢀtheꢀuseꢀofꢀaꢀcombinationꢀofꢀLiO Buꢀandꢀ

120ꢀ
MohammadꢀLokmanꢀHossainꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ115–122ꢀ
Schemeꢀ 3.ꢀ Reactionsꢀ ofꢀ N‐tosylhydrazonesꢀ derivedꢀ fromꢀ unsymmet‐
ricalꢀdiarylmethanone.ꢀTheꢀreactionsꢀwereꢀconductedꢀunderꢀtheꢀsame
conditionsꢀasꢀthoseꢀdescribedꢀaboveꢀinꢀSchemeꢀ2.ꢀTheꢀyieldsꢀreferꢀtoꢀthe
isomericꢀmixturesꢀpriorꢀtoꢀbeingꢀpurifiedꢀbyꢀcolumnꢀchromatography.ꢀ
Schemeꢀ 5.ꢀ Proposedꢀ reactionꢀ mechanismꢀ ofꢀ Cu(I)‐catalyzedꢀ cascadeꢀ
reactionꢀofꢀN‐tosylhydrazonesꢀwithꢀ3‐butyn‐1‐ol.ꢀ
theseꢀ
reactionsꢀ
affordedꢀ
theꢀ
correspondingꢀ
2‐(diarylmethylene)tetrahydrofuransꢀ 3a–kꢀ inꢀ moderateꢀ toꢀ
goodꢀ yields.ꢀ Notably,ꢀ N‐tosylhydrazonesꢀ bearingꢀ anꢀ elec‐
tron‐richꢀorꢀelectron‐deficientꢀsubstituentꢀonꢀtheꢀpara,ꢀmetaꢀorꢀ
orthoꢀpositionsꢀofꢀtheirꢀaromaticꢀringsꢀwereꢀfoundꢀtoꢀbeꢀgoodꢀ
substratesꢀ forꢀ thisꢀ transformation.ꢀ Theꢀ N‐tosylhydrazoneꢀ de‐
rivedꢀ fromꢀ di‐3‐thienylꢀ ketoneꢀ (1c)ꢀ alsoꢀ reactedꢀ smoothlyꢀ toꢀ
giveꢀtheꢀcorrespondingꢀproductꢀ3cꢀinꢀ63%ꢀyield.ꢀ ꢀ
4,ꢀtheꢀsubstituentꢀatꢀtheꢀparaꢀpositionꢀofꢀtheꢀaromaticꢀringꢀofꢀ
theꢀN‐tosylhydrazonesꢀhadꢀnoꢀdiscernibleꢀimpactꢀonꢀtheꢀreac‐
tion.ꢀ Theꢀ presenceꢀ ofꢀ anꢀ electron‐withdrawingꢀ groupꢀ wasꢀ
thereforeꢀ toleratedꢀ underꢀ theseꢀ conditions,ꢀ affordingꢀ theꢀ cor‐
respondingꢀ 2‐(diarylmethylene)tetrahydrofuransꢀ inꢀ moderateꢀ
yields.ꢀSimilarly,ꢀtheꢀEꢀisomersꢀ8a–cꢀwereꢀdeterminedꢀtoꢀbeꢀtheꢀ
majorꢀproducts,ꢀwithꢀonlyꢀsmallꢀamountsꢀofꢀtheꢀcorrespondingꢀ
Encouragedꢀ byꢀ theꢀ successfulꢀ tandemꢀ cyclizationꢀ ofꢀ theꢀ
symmetricalꢀN‐tosylhydrazonesꢀwithꢀ3‐alkynol,ꢀweꢀproceededꢀ
toꢀ extendꢀ thisꢀ strategyꢀ toꢀ aꢀ seriesꢀ ofꢀ unsymmetricalꢀ
N‐tosylhydrazones,ꢀwhichꢀwereꢀderivedꢀfromꢀtheꢀcorrespond‐
ingꢀ unsymmetricalꢀ ketones.ꢀ Asꢀ shownꢀ inꢀ Schemeꢀ 3,ꢀ
N‐tosylhydrazonesꢀ4a–cꢀreactedꢀwithꢀ3‐alkynolꢀ(2)ꢀtoꢀgiveꢀtheꢀ
correspondingꢀ2‐(diarylmethylene)tetrahydrofuransꢀ5a–cꢀwithꢀ
goodꢀstereoselectivity.ꢀTheꢀoutcomeꢀofꢀtheꢀreactionꢀwasꢀfoundꢀ
toꢀbeꢀlargelyꢀunaffectedꢀbyꢀtheꢀstructureꢀofꢀtheꢀunsymmetricalꢀ
N‐tosylhydrazoneꢀsubstrateꢀorꢀtheꢀnatureꢀofꢀtheꢀsubstituentsꢀonꢀ
theꢀaromaticꢀring.ꢀAllꢀofꢀtheseꢀreactionsꢀgaveꢀtheꢀEꢀisomerꢀasꢀ
theꢀmajorꢀproduct,ꢀwithꢀonlyꢀtraceꢀamountsꢀofꢀtheꢀcorrespond‐
1
Zꢀisomersꢀ9a–cꢀbeingꢀdetectedꢀbyꢀ
HꢀNMRꢀandꢀGC‐MSꢀanalysisꢀ
ofꢀtheꢀcrudeꢀproductsꢀinꢀeachꢀcase.ꢀOnceꢀagain,ꢀtheꢀminorꢀiso‐
mersꢀwereꢀreadilyꢀseparatedꢀorꢀisomerizedꢀtoꢀtheꢀcorrespond‐
ingꢀEꢀisomerꢀbyꢀcolumnꢀchromatographyꢀoverꢀsilicaꢀgel.ꢀ
Basedꢀonꢀtheꢀresultsꢀdescribedꢀaboveꢀweꢀproposedꢀaꢀplausi‐
bleꢀmechanismꢀtoꢀaccountꢀforꢀthisꢀCu(I)‐catalyzedꢀtandemꢀcy‐
clization,ꢀwhichꢀisꢀ shownꢀinꢀ Schemeꢀ 5.ꢀTheꢀinitialꢀreactionꢀofꢀ
3‐butyn‐1‐olꢀwithꢀtheꢀCu(I)ꢀcatalystꢀwouldꢀgiveꢀtheꢀCu(I)ꢀacety‐
lideꢀA,ꢀwhichꢀwouldꢀreactꢀwithꢀtheꢀinꢀsituꢀgeneratedꢀdiazoꢀin‐
termediateꢀBꢀtoꢀgenerateꢀtheꢀCu(I)‐carbeneꢀspeciesꢀC.ꢀTheꢀal‐
kynylꢀ migratoryꢀ insertionꢀ ofꢀ Cu(I)‐carbeneꢀ Cꢀ toꢀ theꢀ carbenicꢀ
carbonꢀwouldꢀgiveꢀintermediateꢀD,ꢀwhichꢀwouldꢀbeꢀprotonatedꢀ
toꢀ giveꢀ allene.ꢀ Finally,ꢀ alleneꢀ Eꢀ wouldꢀ undergoꢀ aꢀ cyclizationꢀ
reactionꢀviaꢀanꢀintramolecularꢀnucleophilicꢀadditionꢀreactionꢀtoꢀ
affordꢀtheꢀfinalꢀproductꢀ3a,ꢀwithꢀtheꢀconcomitantꢀregenerationꢀ
ofꢀtheꢀCu(I)ꢀcatalyst.ꢀ
1
ingꢀZꢀisomersꢀ6a–cꢀbeingꢀdetectedꢀbyꢀcrudeꢀ HꢀNMRꢀandꢀGC‐MSꢀ
analysis.ꢀ Pleasingly,ꢀ theꢀ minorꢀ Zꢀ isomersꢀ wereꢀ separatedꢀ orꢀ
isomerizedꢀ toꢀ theꢀ correspondingꢀ Eꢀ isomersꢀ duringꢀ columnꢀ
chromatographicꢀpurificationꢀoverꢀsilicaꢀgel.ꢀ
Finally,ꢀweꢀinvestigatedꢀtheꢀreactionꢀofꢀseveralꢀunsymmet‐
ricalꢀ N‐tosylhydrazonesꢀ 7a–c,ꢀ whichꢀ wereꢀ derivedꢀ fromꢀ theꢀ
correspondingꢀ aromaticꢀ aldehydes,ꢀ withꢀ 3‐alkynolꢀ (2)ꢀ underꢀ
theꢀoptimizedꢀreactionꢀconditions.ꢀAsꢀdemonstratedꢀinꢀSchemeꢀ
4.ꢀ ꢀ Conclusionsꢀ
CuI (10 mol%)
phen (10 mol%)
TBAB (30 mol%)
Weꢀhaveꢀinvestigatedꢀaꢀ Cu(I)‐catalyzedꢀtandemꢀcyclizationꢀ
reactionꢀofꢀN‐tosylhydrazonesꢀwithꢀ3‐butyn‐1‐ol.ꢀThisꢀreactionꢀ
representsꢀ aꢀ straightforwardꢀ approachꢀ forꢀ theꢀ synthesisꢀ ofꢀ
2‐(diarylmethylene)tetrahydrofuransꢀ andꢀ proceedsꢀ viaꢀ theꢀ
formationꢀ ofꢀ aꢀ carbeneꢀ intermediate,ꢀ followedꢀ byꢀ sequentialꢀ
cyclizationꢀ andꢀ isomerizationꢀ steps.ꢀ Theseꢀ resultsꢀ furtherꢀ
demonstrateꢀtheꢀgeneralityꢀofꢀthisꢀapproachꢀforꢀtheꢀformationꢀ
ofꢀallenesꢀviaꢀtheꢀCu(I)‐catalyzedꢀreactionꢀofꢀN‐tosylhydrazonesꢀ
withꢀterminalꢀalkynesꢀ[27].ꢀ
NNHTs
O
H
O
TsOH (2 equiv.)
70 oC, 2 h
+
+
Ar
H
t
LiO Bu (3 equiv.)
HO
Ar
H
Ar
dioxane (1 mL)
7a-c
2
8a c
-
9a c
0 oC, 4 h
-
9
O
H
O
O
Cl
H
H
F3C
NC
F3C
8
a, 63%
8b, 70%
8c, 58%
Schemeꢀ4.ꢀReactionꢀofꢀN‐tosylhydrazonesꢀderivedꢀfromꢀaromaticꢀalde‐
hydes.ꢀ Theꢀ reactionsꢀ wereꢀ conductedꢀ underꢀ theꢀ sameꢀ conditionsꢀ as
thoseꢀ describedꢀ aboveꢀ inꢀ Schemeꢀ 2.ꢀ Theꢀ yieldsꢀ referꢀ toꢀ theꢀ isomeric
mixturesꢀpriorꢀtoꢀtheirꢀpurificationꢀbyꢀcolumnꢀchromatography.ꢀ
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MohammadꢀLokmanꢀHossainꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ115–122ꢀ
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Chin.ꢀJ.ꢀCatal.,ꢀ2017,ꢀ38:ꢀ115–122ꢀ ꢀ ꢀ doi:ꢀ10.1016/S1872‐2067(16)62565‐2
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