CuI-Catalyzed: One-Pot Synthesis of Diaryl Disulfides from Aryl...

Hindawi Publishing CorporationJournal of ChemistryVolume 2013 Article ID 725265 5 pageshttpdxdoiorg1011552013725265

Research ArticleCuI-Catalyzed One-Pot Synthesis of Diaryl Disulfides fromAryl Halides and Carbon Disulfide

Mohammad Soleiman-Beigi and Azadeh Izadi

Department of Chemistry Ilam University PO Box 69315-516 Ilam 6939177111 Iran

Correspondence should be addressed to Mohammad Soleiman-Beigi soleimanbeigiyahoocom

Received 13 May 2013 Accepted 11 July 2013

Academic Editor Albert Demonceau

Copyright copy 2013 M Soleiman-Beigi and A Izadi This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

A new application of carbon disulfide in the presence of KFAl2O3is reported for the synthesis of organic symmetrical diaryl

disulfides These products were synthesized by one-pot reaction of aryl halides with the in situ generated trithiocarbonate ion inthe presence of copper under air atmosphere

1 Introduction

Carbon disulfide is a very important reagent for which manyand varied uses have been reported in chemistry and alsoserves as an industrial and chemical nonpolar solvent [1ndash3]The compound is frequently used as a building block in syn-thetic chemistry for the preparation of trithiocarbonates [4ndash9] dithio- and monothio-carbamates and carbonates [10 11]thiourea [12 13] and other organic compounds containingsulfur or thiocarbonyl (C=S) moiety [14ndash16] Interestinglycarbon disulfide is also used for the synthesis of diaryldisulfides from diazonium salts under conditions of radicalicpathway [17 18]

In continuation of our efforts to synthesize organiccompounds containing sulfur and to use carbon disulfide inorganic reactions [4ndash6 19 20] we report a method for thedirect synthesis of symmetrical diaryl disulfides via dominocoupling reactions of aryl halides with the trithiocarbonateanion However recently symmetrical diaryl trithiocarbon-ates are synthesized from the reaction of Na

2S and CS

2with

Ar-X in the presence of CuI [21] In our process KFAl2O3

was used as a strong recyclable and heterogeneous basewhich has a history of use in both synthetic methodologyreactions [22ndash27] and the in situ production of the trithio-carbonate ion from carbon disulfide [4]

Organic disulfides are also valuable compounds in syn-thetic chemistry industry and biochemistry [28 29] They

are typically prepared by oxidation of the correspondingthiols [30ndash36]There are a limited number of methods for thedirect synthesis of disulfides from aryl halides [20 37]

2 Results and Discussion

To find the optimal reaction conditions in terms of temper-ature and type of copper source the coupling reaction ofthe carbon disulfide with iodobenzene was examined in thepresence of KFAl

2O3under air (Scheme 1)

The trithiocarbonate anion was prepared by the in situreaction of three equivalents of carbon disulfide in thepresence of 10 gram of KF (40 by weight)Al

2O3in DMF

First the effect of different copper salts was examined As isshown in Table 1 copper iodide can catalyze the synthesisof diphenyl disulfide from phenyl iodide better than thatfrom the other salts tested (Table 1 entry 4) As strongbases are commonly used for CS

3

2minus preparation [10 11]Cs2CO3and KOH were also tested to evaluate the efficiency

of KFAl2O3 They catalyze the reaction under optimized

reaction conditions but not as well as KFAl2O3as the

reaction yields were 65 and 35 respectivelyIt can be deduced from the previous literature reports

that the temperature and the nature of an added ligandsignificantly affect the progress of coupling reactions ofsulfur-containing compounds because some of themhave not

2 Journal of Chemistry

PhS-SPhPh-I + CS2 (2) Cu source 5hrt 15min

(1) KFAl2O3

Scheme 1

Table 1 Optimization of the reaction temperature and screening ofcopper sourcesa

Entry Copper salt Temp (∘C) Isolated yield ()1 CuCl 110 652 CuBr 110 723 Cu2O 110 524 CuI 110 955 CuI 100 886 CuI 80 837 CuI 60 778 CuI 25 15aGeneral reaction conditions carbon disulfide (60mmol) KFAl2O3(10 g 40 KF by weight) copper sources (032mmol) and iodobenzene(20mmol) in DMF (4mL) for 5 h

been carried out at room temperature andor in the absenceof a ligand [38 39] In our studies on the reaction the bestresult was obtained at 110∘C However significant progress ofthe reactionwas also observed at lower temperatures (Table 1entries 6 and 7) In addition the reaction also proceeded wellin the absence of a ligand It seems that CS

3

2minus acts as both aligand and a sulfur source

It was expected that some symmetrical diaryl trithiocar-bonate and thiol would be generated as by-products withthe desired diaryl disulfide However no traces of thesecompounds were found at the end of the reaction Thus alarge number of derivatives of symmetrical diaryl disulfideswere synthesized in good to excellent yields under optimalconditions (Scheme 2 Table 2) Aryl bromides also reactedunder these conditions but not as well as aryl iodides

A wide range of diaryl disulfides was synthesized accord-ing to the nature and position of the attachment of thesubstituents on the aryl groups Thus the products bear-ing different substituents both electron-withdrawing andelectron-donating were obtained at the ortho- para- andmetapositions

Symmetrical diheteroaryl disulfides were readily synthe-sized from the corresponding heteroaryl halides (Table 2entries 7 and 8) The optimal reaction conditions were alsotested for the synthesis of symmetrical dialkyl disulfides(Table 2 entry 13) butwere proved to be ineffective in yieldingthe dibenzyl disulfide and dibenzyl trithiocarbonate (as themajor product) dibenzyl sulfide was obtained in 76 and16 yields respectively Interestingly a high chemoselectivityis observed in the coupling reactions (Table 2 entries 11 and5) It is the case of 1-bromo-24-difluorobenzene to bis-(24-diflouro phenyl) disulfide (Table 2 entry 11) and 1-bromo-4-iodobenzene to bis-(4-bromo phenyl) disulfide (Table 2entry 5) yielded as the main products The reactivity ofcarbonndashhalide (CndashX) bonds in aryl halides (ArndashX) probably

ArS-SArrt 15min

(1) KFAl2O3

(2) CuI 110∘C 5hAr-X + CS2

X = Br I

Scheme 2

depends on the nature of the halides As was seen thereactivity of carbonndashX bonds is in the order of CndashI gt CndashBr gtCndashF (Table 2 entries 4 and 10 7 and 8 5 11)

Although we cannot yet clearly delineate the catalyticreaction pathway for the synthesis of diaryl disulfides fromaryl halides and CS

3

2minus it is possible that this reaction pro-ceeds through an additionoxidation Cu(I)-catalyst reactionof trithiocarbonate anion to aryl halides to generate an aryltrithiocarbonate ion via Ullman-type mechanism and thenthe fragmentation of formed aryl trithiocarbonate anion intocarbon disulfide and aryl thiolate [40] which is followed bythiolate oxidation to corresponding disulfides in the presenceof KFAl

2O3[41 42] Aryl (alkyl) halides are activated via

a Cu(I)Cu(II) redox couple single electron transfer (SET)[43]

3 Conclusion

In summary in this study carbon disulfide was used asan inexpensive and readily available source of sulfur in thepresence of KFAl

2O3 The reaction proceeds well under air

This strategy provides a new method for the direct synthesisof symmetrical diaryl disulfides from aryl halides and CS

3

2minusOther advantages of this process are the ability to reuse therecyclable base KFAl

2O3 ease of performing and controlling

the reaction as well as purification of the product and theavoidance of expensive andor dangerous reagents

4 Experimental

41 Direct Synthesis of Diaryl Disulfides from Aryl Halides andTrithiocarbonate Ion General Procedure 6mmol of carbondisulfide and 2mmol of aryl halide were added to a two-neckflask containing 4mL of DMF and 10 gram of KF (40 byweight)Al

2O3[4 44] The mixture was vigorously stirred

for 15 minutes at room temperature on a hot-plate magneticstirrer so that it was blood red in color Then 032mmol(60mg) of CuI was added and the reaction continued at110∘C under air atmosphere and in a condenser until thereaction was completed (5 h) The reaction progress wascontrolled by TLC The reaction mixture was then filteredthe filtrate was evaporated under vacuum CH

2Cl2(20mL)

was added and the mixture washed with H2O (2 lowast 15mL)

The organic layer was dried over anhydrous Na2SO4 The

solvent was evaporated to give the crude diaryl disulfidewhich was purified by plate chromatography (silica gel n-hexane ethyl acetate 20 1) All the products are knowncompounds and were characterized by comparison of NMRspectral data and melting points with those reported in theliterature

Journal of Chemistry 3

Table 2 CuI-catalyzed and KFAl2O3 mediated direct synthesis ofdiaryl disulfides from aryl halides and CS

3

2minus at 110∘C

Entry Aryl halide Diaryl disulfide Yield()a

1

IS S 95

2

I

OMe

S S

OMe

MeO

91

3

I

OMe

S S

OMe

OMe

93

4I

CH3 S S

CH3

CH3

85b

5

I

Br

S S

Br

Br

81b

6

I

NH2

S S

NH2

H2N83

7 S I SS

SS 83

8 S BrS

SS

S 65

9

Br

NO2

S S

NO2

O2N82b

10

Br

CH3

S S

CH3

CH3

60

11

Br

F

FS S

F

F F

F

62b

Table 2 Continued


12

I

SS 95b

13

Br

S S Trace

aYield of the isolated product bA small amount of the corresponding diarylsulfide derivative was formed as by-product (5ndash10)

42 Selected Spectral Data for Representative DisulfidesDiphenyl Disulfide (Table 2 entry 1) mp = 59-60∘C (59ndash61∘C lit [31]) 1H NMR (CDCl

3 400MHz) 120575 = 724ndash736

(m 6H) 754 (m 4H)13

C NMR (CDCl3 100MHz) 120575 =

1272 1275 1291 1370

Bis(4-mathoxyphenyl) Disulfide (Table 2 entry 2) mp = 42-43∘C (42-43∘C lit [34 35]) 1H NMR (CDCl

3 400MHz)

120575 = 382 (s 6H) 687 (d 119869 = 88Hz 4H) 732 (d119869 = 88Hz 4H)

13

C NMR (CDCl3 100MHz) 120575 =

554 1147 1274 1328 1590

Bis(thiophen-2-yl) Disulfide (Table 2 entry 7) mp = 54-55∘C(54ndash56∘C lit [36]) 1H NMR (CDCl

3 400MHz) 120575 = 1H

NMR (CDCl3 400MHz) 120575 697ndash700 (m 2H) 722ndash725 (m

2H) 736ndash738 (m 2H)13

C NMR (CDCl3 100MHz) 120575 =

1154 1207 1297 1554

References

[1] H Werner ldquoNovel coordination compounds formed from cs2and heteroallenesrdquoCoordination Chemistry Reviews vol 43 pp165ndash185 1982

[2] J E Stauffer ldquoExtraction of bitumen from oil sandsrdquo US0101980 2010

[3] B Ochiai and T Endo ldquoCarbon dioxide and carbon disulfide asresources for functional polymersrdquo Progress in Polymer Sciencevol 30 no 2 pp 183ndash215 2005

[4] B Movassagh M Soleiman-Beigi and M Nazari ldquoA facileKFAl

2O3-mediated one-pot synthesis of symmetrical trithio-

carbonates from alkyl halides and carbon disulfiderdquo ChemistryLetters vol 37 no 1 pp 22ndash23 2008

[5] M Soleiman-Beigi Z Arzehgar and B Movassagh ldquoTBAH-catalyzed one-pot synthesis of symmetrical trithiocarbonatesfrom alkyl halides and carbon disulfide under neat aqueousconditionsrdquo Synthesis no 3 pp 392ndash394 2010

[6] B Movassagh and M Soleiman-Beigi ldquoTriethylamine-catalyzed one-pot synthesis of trithiocarbonates from carbondisulfide thiols and alkyl halides in waterrdquo Monatshefte furChemie vol 139 no 8 pp 927ndash930 2008


[7] N Aoyagi B Ochiai H Mori and T Endo ldquoMild and efficientone-step synthesis of trithiocarbonates usingminimumamountof CS

2rdquo Synlett no 4 pp 636ndash638 2006

[8] I Degani R Fochi A Gatti and V Regondi ldquoPhase-transfersynthesis of symmetrical and unsymmetrical dialkyl trithiocar-bonatesrdquo Synthesis no 11 pp 894ndash899 1986

[9] B Movassagh and S J Alapour ldquoK3PO4-mediated one-pot

synthesis of symmetrical trithiocarbonatesrdquo Journal of SulfurChemistry vol 34 no 3 pp 222ndash226 2013

[10] R N Salvatore S Sahab and K W Jung ldquoMild and efficientsynthesis of thiocarbonates and thiocarbamates via a three-component coupling utilizing Cs

2CO3and TBAIrdquo Tetrahedron

Letters vol 42 no 11 pp 2055ndash2058 2001[11] F Dehmel S Weinbrenner H Julius et al ldquoTrithiocarbonates

as a novel class of HDAC inhibitors SAR studies isoenzymeselectivity and pharmacolozgical profilesrdquo Journal of MedicinalChemistry vol 51 no 13 pp 3985ndash4001 2008

[12] R Ballini G Bosica D Fiorini et al ldquoMCM-41-TBD as a newefficient supported heterogeneous catalyst for the synthesis ofthioureasrdquo Tetrahedron Letters vol 43 no 47 pp 8445ndash84472002

[13] U Boas H Gertz J B Christensen and P M H HeegaardldquoFacile synthesis of aliphatic isothiocyanates and thioureason solid phase using peptide coupling reagentsrdquo TetrahedronLetters vol 45 no 2 pp 269ndash272 2004

[14] M Ballabeni R Ballini F Bigi et al ldquoSynthesis of symmetricalNN1015840-disubstituted thioureas and heterocyclic thiones fromamines and CS2 over a ZnOAl

2O3composite as heterogeneous

and reusable catalystrdquo Journal of Organic Chemistry vol 64 no3 pp 1029ndash1032 1999

[15] P A Ottersbach P W Elsinghorst H-G Hacker and MGutschow ldquoDirect formation of ring-fused 13-thiazine-24-dithiones from aromatic o-amino carboxylic acids observationof a carbon disulfide mediated thionationrdquo Organic Letters vol12 no 16 pp 3662ndash3665 2010

[16] M Benaglia E Rizzardo A Alberti andM Guerra ldquoSearchingformore effective agents and conditions for the RAFT polymer-ization of MMA influence of dithioester substituents solventand temperaturerdquoMacromolecules vol 38 no 8 pp 3129ndash31402005

[17] F Barba F Ranz and B Batanero ldquoElectrochemical transfor-mation of diazonium salts into diaryl disulfidesrdquo TetrahedronLetters vol 50 no 49 pp 6798ndash6799 2009

[18] L Benati and P C Montevecchi ldquoReactivity of carbon disulfidewith aryl radicalsrdquo Journal of Organic Chemistry vol 41 no 15pp 2639ndash2640 1976

[19] M Soleiman-Beigi R Aryan M Yousofizadeh and Sh Khos-ravi ldquoA Combined Synthetic and DFT Study on the Catalyst-Free and Solvent-Assisted Synthesis of 134-Oxadiazole-2-ThiolDerivativesrdquo Journal of Chemistry Article ID 476358 pp 1ndash62013

[20] M Soleiman-Beigi and F Mohammadi ldquoA novel copper-catalyzed one-pot synthesis of symmetric organic disul-fides from alkyl and aryl halides potassium 5-methyl-134-oxadiazole-2-thiolate as a novel sulfur transfer reagentrdquo Tetra-hedron Letters vol 53 no 52 pp 7028ndash7030 2012

[21] M Gholinejad ldquoOne-pot synthesis of symmetrical diaryltrithiocarbonates through copper-catalyzed coupling of arylcompounds sodium sulfide and carbon disulfiderdquo EuropeanJournal of Organic Chemistry no 2 pp 257ndash259 2013

[22] G W Kabalka L Wang V Namboodiri and R M PagnildquoRapid microwave-enhanced solventless Sonogashira coupling

reaction on aluminardquo Tetrahedron Letters vol 41 no 27 pp5151ndash5154 2000

[23] B E Blass ldquoKFAl2O3Mediated organic synthesisrdquo Tetrahe-

dron vol 58 no 46 pp 9301ndash9320 2002[24] A Zare A Hasaninejad M H Beyzavi et al ldquoKFAl

2O3as

a highly efficient green heterogeneous and reusable catalyticsystem for the solvent-free synthesis of carboacyclic nucleosidesvia Michael addition reactionrdquo Synthetic Communications vol39 no 1 pp 139ndash157 2009

[25] A Zare A Hasaninejad M H Beyzavi et al ldquoKFAl2O3

as an efficient green and reusable catalytic system for thesolvent-free synthesis of N-Alkyl derivatives of sulfonamidesvia michael reactionsrdquo Phosphorus Sulfur and Silicon and theRelated Elements vol 184 no 7 pp 1702ndash1712 2009

[26] A Zare A Hasaninejad A R Moosavi-Zare et al ldquoKFAl2O3

as a highly efficient reagent for the synthesis of N-aryl deriva-tives of pyrimidine and purine nucleobasesrdquo Arkivoc vol 2008no 16 pp 178ndash188 2008

[27] A Zare A Hasaninejad A R Moosavi-Zre et al ldquoKFAl2O3

as an efficient catalyst for the synthesis of N-alkylphthalimidesrdquoJournal of theChemical Society of Pakistan vol 31 no 2 pp 309ndash313 2009

[28] S Oae Organic Sulfur Chemistry Structure and MechanismCRC Boca Raton Fla USA 1991

[29] R J CremlynAn Introduction toOrganosulfurChemistryWileyand Sons New York NY USA 1996

[30] A Christoforou G Nicolaou and Y Elemes ldquoN-Phenyltriazolinedione as an efficient selective and reusablereagent for the oxidation of thiols to disulfidesrdquo TetrahedronLetters vol 47 no 52 pp 9211ndash9213 2006

[31] R Leino and J-E Lonnqvist ldquoA very simple method for thepreparation of symmetrical disulfidesrdquo Tetrahedron Letters vol45 no 46 pp 8489ndash8491 2004

[32] K Tanaka and K Ajiki ldquoCationic rhodium(I)PPh3 complex-catalyzed dehydrogenation of alkanethiols to disulfides underinert atmosphererdquo Tetrahedron Letters vol 45 no 1 pp 25ndash272004

[33] R Hunter M Caira and N Stellenboom ldquoInexpensiveone-pot synthesis of unsymmetrical disulfides using 1-chlorobenzotriazolerdquo Journal of Organic Chemistry vol 71 no21 pp 8268ndash8271 2006

[34] J K Vandavasi W-P Hu C-Y Chen and J-J Wang ldquoEfficientsynthesis of unsymmetrical disulfidesrdquo Tetrahedron vol 67 no46 pp 8895ndash8901 2011

[35] C C Silveira and S R Mendes ldquoCatalytic oxidation of thiols todisulfides using iodine and CeCl

3-7H2O in graphiterdquo Tetrahe-

dron Letters vol 48 no 42 pp 7469ndash7471 2007[36] G W Kabalka M S Reddy and M-L Yao ldquoSynthesis of diaryl

disulfides via the reductive coupling of arylsulfonyl chloridesrdquoTetrahedron Letters vol 50 no 52 pp 7340ndash7342 2009

[37] J E Arguello L C Schmidt and A B Penenory ldquolsquoOne-Potrsquotwo-step synthesis of aryl sulfur compounds by photoinducedreactions of thiourea anion with aryl halidesrdquo Organic Lettersvol 5 no 22 pp 4133ndash4136 2003

[38] S Yasuike M Nishioka N Kakusawa and J Kurita ldquoSimpleand efficient copper-catalyzed S-arylation of diaryl disulfideswith triarylbismuthanes under aerobic conditionsrdquoTetrahedronLetters vol 52 no 48 pp 6403ndash6406 2011

[39] B Basu B Mandal S Das and S Kundu ldquoCatechol violetas new efficient and versatile ligand for Cu(I)-catalyzed C-S coupling reactionsrdquo Tetrahedron Letters vol 50 no 39 pp5523ndash5528 2009


[40] E J Lenardao R G Lara M S Silva R G Jacob and G PerinldquoClean and fast oxidative transformation of thiols to disulfidesunder solvent-free conditionsrdquo Tetrahedron Letters vol 48 no43 pp 7668ndash7670 2007

[41] S Tanimoto T Oida H Ikehira and M Okano ldquoSynthesisand Lithiation of 2-Alkylthio- and 2-Arylthio-13-dithiolanesrdquoBulletin of the Chemical Society of Japan vol 55 no 6 pp 1977ndash1978 1982

[42] A Sugawara M Shirahata S Sato and R Sato ldquoOne-pot syn-thesis of alkyl aryl trithiocarbonates from benzenethiols alkylhalides and carbon disulfide with a phase-transfer catalystrdquoBulletin of the Chemical Society of Japan vol 57 no 11 pp 3353ndash3354 1984

[43] E Sperotto G PMVanKlink G VanKoten and J GDeVriesldquoThe mechanism of the modified Ullmann reactionrdquo DaltonTransactions vol 39 no 43 pp 10338ndash10351 2010

[44] V K Yadav K Ganesh Babu and M Mittal ldquoKF-Al2O3is an

efficient solid support reagent for the acetylation of aminesalcohols and phenols Impeding effect of solvent on the reactionraterdquo Tetrahedron vol 57 no 32 pp 7047ndash7051 2001

Impact Factor 173028 Days Fast Track Peer ReviewAll Subject Areas of ScienceSubmit at httpwwwtswjcom

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawi Publishing Corporation httpwwwhindawicom Volume 2013

The Scientific World Journal


PhS-SPhPh-I + CS2 (2) Cu source 5hrt 15min

(1) KFAl2O3

Scheme 1

Table 1 Optimization of the reaction temperature and screening ofcopper sourcesa

Entry Copper salt Temp (∘C) Isolated yield ()1 CuCl 110 652 CuBr 110 723 Cu2O 110 524 CuI 110 955 CuI 100 886 CuI 80 837 CuI 60 778 CuI 25 15aGeneral reaction conditions carbon disulfide (60mmol) KFAl2O3(10 g 40 KF by weight) copper sources (032mmol) and iodobenzene(20mmol) in DMF (4mL) for 5 h

been carried out at room temperature andor in the absenceof a ligand [38 39] In our studies on the reaction the bestresult was obtained at 110∘C However significant progress ofthe reactionwas also observed at lower temperatures (Table 1entries 6 and 7) In addition the reaction also proceeded wellin the absence of a ligand It seems that CS

3

2minus acts as both aligand and a sulfur source

It was expected that some symmetrical diaryl trithiocar-bonate and thiol would be generated as by-products withthe desired diaryl disulfide However no traces of thesecompounds were found at the end of the reaction Thus alarge number of derivatives of symmetrical diaryl disulfideswere synthesized in good to excellent yields under optimalconditions (Scheme 2 Table 2) Aryl bromides also reactedunder these conditions but not as well as aryl iodides

A wide range of diaryl disulfides was synthesized accord-ing to the nature and position of the attachment of thesubstituents on the aryl groups Thus the products bear-ing different substituents both electron-withdrawing andelectron-donating were obtained at the ortho- para- andmetapositions

Symmetrical diheteroaryl disulfides were readily synthe-sized from the corresponding heteroaryl halides (Table 2entries 7 and 8) The optimal reaction conditions were alsotested for the synthesis of symmetrical dialkyl disulfides(Table 2 entry 13) butwere proved to be ineffective in yieldingthe dibenzyl disulfide and dibenzyl trithiocarbonate (as themajor product) dibenzyl sulfide was obtained in 76 and16 yields respectively Interestingly a high chemoselectivityis observed in the coupling reactions (Table 2 entries 11 and5) It is the case of 1-bromo-24-difluorobenzene to bis-(24-diflouro phenyl) disulfide (Table 2 entry 11) and 1-bromo-4-iodobenzene to bis-(4-bromo phenyl) disulfide (Table 2entry 5) yielded as the main products The reactivity ofcarbonndashhalide (CndashX) bonds in aryl halides (ArndashX) probably

ArS-SArrt 15min

(1) KFAl2O3

(2) CuI 110∘C 5hAr-X + CS2

X = Br I

Scheme 2

depends on the nature of the halides As was seen thereactivity of carbonndashX bonds is in the order of CndashI gt CndashBr gtCndashF (Table 2 entries 4 and 10 7 and 8 5 11)

Although we cannot yet clearly delineate the catalyticreaction pathway for the synthesis of diaryl disulfides fromaryl halides and CS

3

2minus it is possible that this reaction pro-ceeds through an additionoxidation Cu(I)-catalyst reactionof trithiocarbonate anion to aryl halides to generate an aryltrithiocarbonate ion via Ullman-type mechanism and thenthe fragmentation of formed aryl trithiocarbonate anion intocarbon disulfide and aryl thiolate [40] which is followed bythiolate oxidation to corresponding disulfides in the presenceof KFAl

2O3[41 42] Aryl (alkyl) halides are activated via

a Cu(I)Cu(II) redox couple single electron transfer (SET)[43]

3 Conclusion

In summary in this study carbon disulfide was used asan inexpensive and readily available source of sulfur in thepresence of KFAl

2O3 The reaction proceeds well under air

This strategy provides a new method for the direct synthesisof symmetrical diaryl disulfides from aryl halides and CS

3

2minusOther advantages of this process are the ability to reuse therecyclable base KFAl

2O3 ease of performing and controlling

the reaction as well as purification of the product and theavoidance of expensive andor dangerous reagents

4 Experimental

41 Direct Synthesis of Diaryl Disulfides from Aryl Halides andTrithiocarbonate Ion General Procedure 6mmol of carbondisulfide and 2mmol of aryl halide were added to a two-neckflask containing 4mL of DMF and 10 gram of KF (40 byweight)Al

2O3[4 44] The mixture was vigorously stirred

for 15 minutes at room temperature on a hot-plate magneticstirrer so that it was blood red in color Then 032mmol(60mg) of CuI was added and the reaction continued at110∘C under air atmosphere and in a condenser until thereaction was completed (5 h) The reaction progress wascontrolled by TLC The reaction mixture was then filteredthe filtrate was evaporated under vacuum CH

2Cl2(20mL)

was added and the mixture washed with H2O (2 lowast 15mL)

The organic layer was dried over anhydrous Na2SO4 The

solvent was evaporated to give the crude diaryl disulfidewhich was purified by plate chromatography (silica gel n-hexane ethyl acetate 20 1) All the products are knowncompounds and were characterized by comparison of NMRspectral data and melting points with those reported in theliterature



3

2minus at 110∘C


1

IS S 95

2

I

OMe

S S

OMe

MeO

91

3

I

OMe

S S

OMe

OMe

93

4I

CH3 S S

CH3

CH3

85b

5

I

Br

S S

Br

Br

81b

6

I

NH2

S S

NH2

H2N83

7 S I SS

SS 83

8 S BrS

SS

S 65

9

Br

NO2

S S

NO2

O2N82b

10

Br

CH3

S S

CH3

CH3

60

11

Br

F

FS S

F

F F

F

62b

Table 2 Continued


12

I

SS 95b

13

Br

S S Trace



3 400MHz) 120575 = 724ndash736

(m 6H) 754 (m 4H)13

C NMR (CDCl3 100MHz) 120575 =

1272 1275 1291 1370


3 400MHz)

120575 = 382 (s 6H) 687 (d 119869 = 88Hz 4H) 732 (d119869 = 88Hz 4H)

13

C NMR (CDCl3 100MHz) 120575 =

554 1147 1274 1328 1590


3 400MHz) 120575 = 1H


2H) 736ndash738 (m 2H)13

C NMR (CDCl3 100MHz) 120575 =

1154 1207 1297 1554

References



































2O3as


































3

2minus at 110∘C


1

IS S 95

2

I

OMe

S S

OMe

MeO

91

3

I

OMe

S S

OMe

OMe

93

4I

CH3 S S

CH3

CH3

85b

5

I

Br

S S

Br

Br

81b

6

I

NH2

S S

NH2

H2N83

7 S I SS

SS 83

8 S BrS

SS

S 65

9

Br

NO2

S S

NO2

O2N82b

10

Br

CH3

S S

CH3

CH3

60

11

Br

F

FS S

F

F F

F

62b

Table 2 Continued


12

I

SS 95b

13

Br

S S Trace



3 400MHz) 120575 = 724ndash736

(m 6H) 754 (m 4H)13

C NMR (CDCl3 100MHz) 120575 =

1272 1275 1291 1370


3 400MHz)

120575 = 382 (s 6H) 687 (d 119869 = 88Hz 4H) 732 (d119869 = 88Hz 4H)

13

C NMR (CDCl3 100MHz) 120575 =

554 1147 1274 1328 1590


3 400MHz) 120575 = 1H


2H) 736ndash738 (m 2H)13

C NMR (CDCl3 100MHz) 120575 =

1154 1207 1297 1554

References



































2O3as


























































2O3as
































CuI-Catalyzed: One-Pot Synthesis of Diaryl Disulfides from Aryl...

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Transcript of CuI-Catalyzed: One-Pot Synthesis of Diaryl Disulfides from Aryl...