Direct construction of sulfenylated pyrazoles catalyzed by I2 at room temperature

Article abstract of DOI:10.1016/S1872-2067(17)62901-2

An iodine-catalyzed sulfenylation of pyrazoles at room temperature is described, in which a variety of pyrazoles were well tolerated and the desired products were obtained in good to excellent yields.

Full text of DOI:10.1016/S1872-2067(17)62901-2

ChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ1664–1667
ꢀ
ꢀ ꢀ
ꢀ ꢀ ꢀ ꢀ
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
ꢀ
ꢀ
Communication
DirectꢀconstructionꢀofꢀsulfenylatedꢀpyrazolesꢀcatalyzedꢀbyꢀI
temperatureꢀ
2
ꢀatꢀroomꢀ
†
†
Shuang‐HongꢀHaoꢀ ,ꢀLi‐XiaꢀLiꢀ ,ꢀDao‐QingꢀDong,ꢀZu‐LiꢀWangꢀ*
ꢀ
CollegeꢀofꢀChemistryꢀandꢀPharmaceuticalꢀSciences,ꢀQingdaoꢀAgriculturalꢀUniversity,ꢀQingdaoꢀ266109,ꢀShangdong,ꢀChinaꢀ
A R T I C L E ꢀ I N F O ꢀ
A B S T R A C T ꢀ
Articleꢀhistory:ꢀ
Anꢀiodine‐catalyzedꢀsulfenylationꢀofꢀpyrazolesꢀatꢀroomꢀtemperatureꢀisꢀdescribed,ꢀinꢀwhichꢀaꢀvarietyꢀ
ofꢀpyrazolesꢀwereꢀwellꢀtoleratedꢀandꢀtheꢀdesiredꢀproductsꢀwereꢀobtainedꢀinꢀgoodꢀtoꢀexcellentꢀyields.
©ꢀ2017,ꢀDalianꢀInstituteꢀofꢀChemicalꢀPhysics,ꢀChineseꢀAcademyꢀofꢀSciences.
PublishedꢀbyꢀElsevierꢀB.V.ꢀAllꢀrightsꢀreserved.
Receivedꢀ6ꢀJulyꢀ2017ꢀ
Acceptedꢀ14ꢀAugustꢀ2017ꢀ
Publishedꢀ5ꢀOctoberꢀ2017ꢀ
Keywords:ꢀ
C–Sꢀbondꢀ
Iodineꢀ
Roomꢀtemperatureꢀ
Disulfidesꢀ
Sulfenylation
Sulfur‐containingꢀcompoundsꢀareꢀcrucialꢀforꢀtheꢀsynthesisꢀofꢀ
diverseꢀ moleculesꢀ inꢀ organicꢀ synthesis,ꢀ theꢀ pharmaceuticalꢀ
industry,ꢀandꢀmaterialsꢀscienceꢀ[1–9].ꢀInꢀtheꢀlastꢀfewꢀdecades,ꢀ
muchꢀeffortꢀhasꢀbeenꢀdevotedꢀtoꢀdevelopingꢀnewꢀmethodsꢀforꢀ
C–Sꢀ bondꢀ construction.ꢀ Amongꢀ theseꢀ approaches,ꢀ transi‐
tion‐metalꢀ catalyzedꢀ crossꢀ couplingꢀ reactionsꢀ areꢀ amongꢀ theꢀ
mostꢀpowerfulꢀtoolsꢀforꢀC–Sꢀbondꢀformationꢀ[10–18].ꢀHowever,ꢀ
someꢀ ofꢀ theseꢀ methodsꢀ requireꢀ expensiveꢀ andꢀ air‐sensitiveꢀ
metalꢀcatalysts,ꢀandꢀareꢀnotꢀenvironmentallyꢀbenign.ꢀTherefore,ꢀ
directꢀsulfenylationꢀreactionsꢀunderꢀmetalꢀfreeꢀconditionsꢀhaveꢀ
receivedꢀincreasingꢀinterestꢀrecentlyꢀ[19–32].ꢀForꢀexample,ꢀinꢀ
presenceꢀ ofꢀ Cs
2
CO ꢀ [34].ꢀ Inꢀ 2016,ꢀ Luꢀ etꢀ al.ꢀ showedꢀ thatꢀ arylꢀ
3
sulfonylꢀchloridesꢀwereꢀgoodꢀreagentsꢀforꢀtheꢀsulfenylationꢀofꢀ
pyrazolonesꢀ andꢀ benzofuransꢀ [35].ꢀ Inꢀ 2016,ꢀ anotherꢀ systemꢀ
consistingꢀofꢀKIO ꢀandꢀairꢀwasꢀdisclosedꢀbyꢀWanꢀetꢀal.ꢀforꢀtheꢀ
α‐sulfenylationꢀofꢀenaminonesꢀandꢀrelatedꢀenaminesꢀ[36].ꢀFur‐
thermore,ꢀ Wangꢀ etꢀal.ꢀ reportedꢀ thatꢀ theꢀ directꢀ arylthiationꢀ ofꢀ
substitutedꢀ anilinesꢀ wasꢀ realizedꢀ inꢀ theꢀ presentꢀ ofꢀ I
di‐tert‐butylꢀ peroxideꢀ [37].ꢀ Inꢀ 2017,ꢀ Songꢀ etꢀ al.ꢀ describedꢀ anꢀ
electrolyticꢀC–Hꢀthiolationꢀreactionꢀcatalyzedꢀbyꢀ(2,2,6,6‐tetra‐
methyl‐piperidin‐1‐yl)oxylꢀ (TEMPO)ꢀ forꢀ theꢀ synthesisꢀ ofꢀ ben‐
zothiazolesꢀandꢀthiazolopyridinesꢀ[38].ꢀHowever,ꢀnewꢀversatileꢀ
andꢀpracticalꢀmethodsꢀforꢀC–Sꢀbondꢀsynthesisꢀremainꢀdesirable.ꢀ
Asꢀpartꢀofꢀourꢀcontinuingꢀeffortsꢀtowardꢀiodine‐catalyzedꢀreac‐
tionsꢀ[39,40],ꢀweꢀnowꢀdiscloseꢀaꢀnewꢀstrategyꢀforꢀtheꢀconven‐
ientꢀandꢀhighlyꢀefficientꢀiodine‐catalyzedꢀsynthesisꢀofꢀsulfenyl‐
atedꢀpyrazolesꢀatꢀroomꢀtemperature.ꢀ
3
2
ꢀ andꢀ
ꢀ
2016,ꢀanꢀiodineꢀcatalyzedꢀregioselectiveꢀsulfenylationꢀofꢀimid‐
azoheterocyclesꢀusingꢀdimethylꢀsulfoxideꢀasꢀbothꢀoxidantꢀandꢀ
solventꢀwasꢀreportedꢀbyꢀPrabhuꢀetꢀal.ꢀ[33].ꢀAnꢀefficientꢀmethodꢀ
usingꢀanꢀionicꢀliquidꢀasꢀsolventꢀwasꢀdevelopedꢀbyꢀZhangꢀetꢀal.ꢀ
forꢀ theꢀ synthesisꢀ ofꢀ 3‐sulfenylꢀ imidazo[1,2‐a]pyridinesꢀ inꢀ theꢀ
*
ꢀ
ꢀCorrespondingꢀauthor.ꢀE‐mail:ꢀwangzulichem@163.comꢀ
Theseꢀauthorsꢀcontributedꢀequallyꢀtoꢀthisꢀarticle.ꢀ
†
ThisꢀworkꢀwasꢀsupportedꢀbyꢀtheꢀNationalꢀNaturalꢀScienceꢀFoundationꢀofꢀChinaꢀ(21402103,ꢀ21772107,ꢀ31471808),ꢀtheꢀChinaꢀPostdoctoralꢀScienceꢀ
Foundationꢀ(150030),ꢀandꢀtheꢀResearchꢀFundꢀofꢀQingdaoꢀAgriculturalꢀUniversity'sꢀHighlevelꢀPersonꢀ(631303).ꢀ
DOI:ꢀ10.1016/S1872‐2067(17)62901‐2ꢀ|ꢀhttp://www.sciencedirect.com/science/journal/18722067ꢀ|ꢀChin.ꢀJ.ꢀCatal.,ꢀVol.ꢀ38,ꢀNo.ꢀ10,ꢀOctoberꢀ2017ꢀ ꢀ ꢀ

ꢀ
Shuang‐HongꢀHaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ1664–1667ꢀ
1665ꢀ
Theꢀ reactionꢀ ofꢀ 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐oneꢀ
1a)ꢀwithꢀdisulfideꢀ(2a)ꢀinꢀtheꢀpresenceꢀofꢀH ꢀwasꢀchosenꢀasꢀ
theꢀ modelꢀ reactionꢀ toꢀ optimizeꢀ conditions.ꢀ Initially,ꢀ variousꢀ
catalystsꢀwereꢀscreened,ꢀwithꢀtheꢀhighestꢀyieldꢀ(88%)ꢀobtainedꢀ
N
N
N
N
N
N
N
N
S
S
S
(
O
2 2
S
OH
b, 92%
OH
OH
OH
Cl
Cl
3c, 93%
3
3d, 97%
3
a, 88%
NO2
NO2
usingꢀ I
2
ꢀ asꢀ catalystꢀ (Tableꢀ 1,ꢀ entryꢀ 5).ꢀ Usingꢀ N‐
ꢀ
bromobu‐
N
N
N
N
S
N
N
N
N
S
S
S
tanimideꢀ (NBS)ꢀ asꢀ theꢀ catalyst,ꢀ desiredꢀ productꢀ 3aꢀ wasꢀ ob‐
tainedꢀ inꢀ onlyꢀ 43%ꢀ yieldꢀ (Tableꢀ 1,ꢀ entryꢀ 1).ꢀ Inꢀ contrast,ꢀ
OH
OH
Cl
Cl
OH
3
OH
3h, 80%
Cl
Cl
3g, 85%
3e, 83%
NO2
f, 78%
Cl
N‐chlorosuccinimideꢀ(NCS),ꢀN‐iodosuccinimideꢀ(NIS),ꢀandꢀNH Iꢀ
4
N
N
N
N
N
N
didꢀnotꢀsuccessfullyꢀcatalyzeꢀtheꢀmodelꢀreactionꢀ(Tableꢀ1,ꢀen‐
triesꢀ 2–4).ꢀ Weꢀ nextꢀ investigatedꢀ theꢀ effectꢀ ofꢀ solventꢀ onꢀ theꢀ
modelꢀreaction,ꢀandꢀfoundꢀthatꢀ1,4‐dioxaneꢀwasꢀsuperiorꢀtoꢀtheꢀ
otherꢀsolvents.ꢀNoꢀdesiredꢀproductꢀwasꢀgeneratedꢀwhenꢀwaterꢀ
wasꢀ usedꢀ asꢀ theꢀ solventꢀ (Tableꢀ 1,ꢀ entryꢀ 10),ꢀ whileꢀ otherꢀ sol‐
S
S
N
N
S
S
OH
OH
OH
HO
Cl
Cl
Cl
3
i, 75%
3l, 89%
3j, 79%
3k, 86%
NO2
NO2
N
N
N
N
N
N
N
S
S
N
S
S
HO
OH
vents,ꢀ suchꢀ asꢀ DMF,ꢀ dichloroethaneꢀ (DCE),ꢀ 1,2‐
thaneꢀ(DME),ꢀandꢀEtOH,ꢀgeneratedꢀtheꢀcorrespondingꢀproductsꢀ
inꢀ(39–67)%ꢀyieldsꢀ(Tableꢀ1,ꢀentriesꢀ6–9).ꢀFurthermore,ꢀwhenꢀ
ꢀ
dimethoxye‐
OH
m, 81%
OH
3
p, 84%
Cl
3
3n, 77%
3o, 81%
2
O N
Cl
N
N
N
N
NO2
N
N
N
S
N
2 2
theꢀamountꢀofꢀH O ꢀwasꢀdecreasedꢀfromꢀ2ꢀtoꢀ1ꢀequiv.,ꢀaꢀslightlyꢀ
N
S
S
S
NO2
HO
OH
t, 80%
lowerꢀyieldꢀofꢀ60%ꢀwasꢀobtainedꢀ(Tableꢀ1,ꢀentryꢀ11).ꢀ
HO
HO
3q, 80%
3r, 83%
3s, 82%
3
Havingꢀobtainedꢀoptimizedꢀreactionꢀconditions,ꢀtheꢀscopeꢀofꢀ
thisꢀreactionꢀwasꢀevaluatedꢀforꢀaꢀvarietyꢀofꢀpyrazolesꢀwithꢀdif‐
ferentꢀsubstitutedꢀdisulfides.ꢀAsꢀshownꢀinꢀSchemeꢀ1,ꢀsubstitut‐
N
N
N
N
S
S
OH N
OH N
3v, 85%
Cl
3
u, 66%
edꢀ pyrazolesꢀ withꢀ eitherꢀ electron‐donatingꢀ orꢀ electron‐with‐
ꢀ
Schemeꢀ 1.ꢀ Scopeꢀ ofꢀ pyrazoleꢀ sulfenylationꢀ usingꢀ disulfides.ꢀ Reactionꢀ
conditions:ꢀPyrazoleꢀ(0.2ꢀmmol),ꢀdisulfideꢀ(0.11ꢀmmol),ꢀI ꢀ(10ꢀmol%),ꢀ
2ꢀinꢀdecaneꢀ(0.4ꢀmmol),ꢀ24ꢀh,ꢀinꢀair.ꢀ
drawingꢀ groupsꢀ wereꢀ wellꢀ toleratedꢀ inꢀ thisꢀ systemꢀ (3a–3d).ꢀ
Chlorine‐substitutedꢀ pyrazolesꢀ reactedꢀ withꢀ aꢀ seriesꢀ ofꢀ disul‐
fidesꢀ smoothly,ꢀ affordingꢀ theꢀ desiredꢀ productꢀ inꢀ (75–93)%ꢀ
yieldsꢀ (3e–3k).ꢀ Furthermore,ꢀ methyl‐substitutedꢀ pyrazolesꢀ
affordedꢀtheꢀdesiredꢀproductsꢀinꢀ(77–97)%ꢀyieldsꢀ(3d,ꢀ3l–3o).ꢀ
Forꢀsubstitutedꢀdisulfides,ꢀtheꢀelectronicꢀeffectsꢀofꢀtheꢀsubstit‐
uentꢀgroupsꢀhadꢀnoꢀsignificantꢀeffectꢀonꢀtheꢀcatalyticꢀefficiencyꢀ
2
solventꢀ(1ꢀmL),ꢀ25ꢀC,ꢀ30%ꢀaq.ꢀH O
2
Isolatedꢀyieldsꢀareꢀshown.ꢀ ꢀ
ꢀ
diphenyldisulfaneꢀ(2a)ꢀwereꢀtestedꢀunderꢀtheꢀoptimizedꢀcondi‐
tions,ꢀproductꢀ(3a)ꢀwasꢀobtainedꢀwithoutꢀaꢀmajorꢀdecreaseꢀinꢀ
yield.ꢀTherefore,ꢀtheꢀpresentꢀmethodꢀshouldꢀbeꢀaꢀrobustꢀmeth‐
odꢀforꢀtheꢀlarge‐scaleꢀsynthesisꢀofꢀsulfenylatedꢀpyrazoles.ꢀ
Toꢀ gainꢀ insightꢀ intoꢀ theꢀ reactionꢀ mechanism,ꢀ controlꢀ ex‐
perimentsꢀ wereꢀ performed,ꢀ asꢀ shownꢀ inꢀ Schemeꢀ 3.ꢀ Whenꢀ
TEMPOꢀwasꢀaddedꢀtoꢀtheꢀreaction,ꢀtheꢀproductꢀyieldꢀwasꢀsig‐
nificantlyꢀdecreasedꢀ(Schemeꢀ3(a)).ꢀThisꢀindicatedꢀthatꢀaꢀradicalꢀ
intermediateꢀmightꢀbeꢀinvolvedꢀinꢀtheꢀreaction.ꢀWhenꢀtheꢀreac‐
(
3p–3s).ꢀ Toꢀ ourꢀ delight,ꢀ whenꢀ 1,2‐di(pyridin‐2‐yl)disulfaneꢀ
ꢀ
wasꢀused,ꢀtheꢀcorrespondingꢀproductsꢀwereꢀobtainedꢀinꢀmod‐
erateꢀtoꢀhighꢀyieldsꢀ(3t–3v).ꢀ
Toꢀdemonstrateꢀtheꢀsyntheticꢀutilityꢀofꢀthisꢀtransformation,ꢀ
aꢀscaledꢀupꢀexperimentꢀ(6ꢀmmol)ꢀwasꢀcarriedꢀoutꢀ(Schemeꢀ2).ꢀ
Whenꢀ 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐oneꢀ (1a)ꢀ andꢀ 1,2‐
ꢀ
tionꢀwasꢀconductedꢀwithoutꢀI
ed,ꢀindicatingꢀtheꢀimportantꢀroleꢀofꢀI
more,ꢀwhenꢀtheꢀreactionꢀofꢀ1aꢀwithꢀ2aꢀwasꢀperformedꢀwithoutꢀ
ꢀ(Schemeꢀ3(c)),ꢀtheꢀyieldsꢀofꢀtheꢀdesiredꢀproductꢀdecreasedꢀ
toꢀ48%.ꢀTheseꢀresultsꢀdemonstratedꢀtheꢀimportanceꢀofꢀI ꢀandꢀ
ꢀinꢀthisꢀreaction.ꢀ
Basedꢀ onꢀ theseꢀ preliminaryꢀ experimentsꢀ andꢀ previousꢀ re‐
portsꢀ [19,41–45],ꢀ aꢀ plausibleꢀ reactionꢀ mechanismꢀ wasꢀ pro‐
posed,ꢀasꢀshownꢀinꢀSchemeꢀ4.ꢀFirstly,ꢀhomolyticꢀcleavageꢀofꢀtheꢀ
disulfideꢀbondꢀoccurs,ꢀformingꢀthiylꢀradicals.ꢀTheꢀthiylꢀradicalsꢀ
2
,ꢀnoꢀdesiredꢀproductꢀwasꢀdetect‐
Tableꢀ1ꢀ
Iodine‐catalyzedꢀsulfenylationꢀofꢀpyrazolesꢀ .ꢀ
2
ꢀ(Schemeꢀ3(b)).ꢀFurther‐
a
H
2 2
O
2
H
2 2
O
ꢀ
ꢀ
b
Entryꢀ
Catalystꢀ(mol%)ꢀ
NBSꢀ(10)ꢀ
Solventꢀ
1,4‐dioxaneꢀ
1,4‐dioxaneꢀ
1,4‐dioxaneꢀ
1,4‐dioxaneꢀ
1,4‐dioxaneꢀ
DMFꢀ
Yield ꢀ(%)ꢀ
1
ꢀ
43ꢀ
0ꢀ
0ꢀ
2
ꢀ
NCSꢀ(10)ꢀ
NISꢀ(10)ꢀ
3ꢀ
thenꢀreactꢀwithꢀI
Finally,ꢀelectrophilicꢀPhSIꢀreactsꢀwithꢀpyrazolesꢀtoꢀproduceꢀtheꢀ
desiredꢀ productꢀ andꢀ HI,ꢀ andꢀ I ꢀ isꢀ readilyꢀ regeneratedꢀ byꢀ theꢀ
oxidationꢀofꢀHIꢀwithꢀH .ꢀ ꢀ
2
ꢀtoꢀgenerateꢀelectrophilicꢀsulfenylꢀiodideꢀPhSI.ꢀ
4
ꢀ
4
NH Iꢀ(10)ꢀ
0ꢀ
5
ꢀ
I
2
ꢀ(10)ꢀ
ꢀ(10)ꢀ
ꢀ(10)ꢀ
ꢀ(10)ꢀ
ꢀ(10)ꢀ
ꢀ(10)ꢀ
ꢀ(10)ꢀ
88ꢀ
54ꢀ
51ꢀ
67ꢀ
39ꢀ
0ꢀ
2
6ꢀ
I
2
O
2 2
7ꢀ
I
2
DCEꢀ
8
9ꢀ
ꢀ
I
I
I
2
2
2
EtOHꢀ
DMEꢀ
1
1
0ꢀ
1ꢀ
2
H Oꢀ
I
2
1,4‐dioxaneꢀ
60ꢀcꢀ
aꢀReactionꢀ conditions:ꢀ 1aꢀ (0.2ꢀ mmol),ꢀ 2aꢀ (0.11ꢀ mmol),ꢀ I
solventꢀ(1ꢀmL),ꢀ25ꢀC,ꢀ30%ꢀaq.ꢀH ꢀinꢀdecaneꢀ(0.4ꢀmmol),ꢀ24ꢀh,ꢀinꢀair.ꢀ
ꢀinꢀdecaneꢀ(0.2ꢀmmol)ꢀwasꢀused.ꢀ
ꢀ (10ꢀ mol%),ꢀ
2
O
2 2
b
c
ꢀ
Isolatedꢀyields.ꢀ ꢀ30%ꢀaq.ꢀH
O
2 2
Schemeꢀ2.ꢀGram‐scaleꢀsynthesisꢀofꢀsulfenylatedꢀpyrazolesꢀ3a.ꢀ

1666ꢀ
Shuang‐HongꢀHaoꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ38ꢀ(2017)ꢀ1664–1667ꢀ
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室温下碘催化直接构建硫化吡唑啉酮
†
†
*
郝双红 , 李丽霞 , 董道青, 王祖利
青岛农业大学化学与药学院, 山东青岛266109
摘要: 含硫化合物在有机合成、药物化学以及材料化学等领域具有重要的作用. 到目前为止, 科学家已经在C‒S键的构建
领域进行了很多工作. 在构建C‒S键的众多方法中, 金属催化的C‒S键合成反应是一类很重要的反应, 但是此方法存在着催
化剂对空气敏感、环境不友好等问题. 因此, 发展无金属催化的C‒S键构建反应受到了人们越来越多的重视. 基于我们在碘
催化相关反应方面的研究, 本文报道了一种碘催化的硫化吡唑啉酮类化合物的合成方法.
我们选用3-甲基-1-苯基-2-吡唑啉-5-酮与二苯二硫醚为底物进行条件筛选实验, 发现I
2
(10%)为催化剂, 二氧六环为溶
剂, H 为氧化剂为最优化的实验条件, 目标产物硫化吡唑啉酮最高产率为88%. 在最优化的反应条件下, 我们尝试了带有
2
O
2
不同官能团(NO , Cl, OH等)的吡唑啉酮与二硫醚的反应, 均能以较高产率得到目标产物. 当含有杂环的二硫醚(2,2'-二硫二
2
吡啶)作为反应底物时, 也能以中等以上的产率得到相应的目标产物. 另外还进行了对比试验, 例如在反应体系中加入自由
基捕获剂TEMPO, 反应产率会大大降低, 说明反应中应该有自由基中间体生成; 如果反应体系中不加碘, 则反应产率为零;
2 2 2 2
如果反应体系中不加H O , 则反应产率由88%降低至48%, 说明碘和H O 在反应中都起到了重要作用. 通过以上对比试验,
提出了可能的反应机理: 首先, 二硫醚发生均裂反应生成苯硫基自由基, 然后苯硫基自由基与碘反应生成亲电的PhSI活性
中间体, PhSI与异构化的吡唑啉酮发生亲电取代反应, 生成目标产物硫化吡唑啉酮和HI, HI可以被H
2 2 2
O 氧化生成I 继续参
与下一轮催化反应.
以3-甲基-1-苯基-2-吡唑啉-5-酮与二苯二硫醚为底物, 我们对此反应进行了放大试验, 结果显示反应产率几乎没有降
低, 这为此反应的大规模应用奠定了基础.
在此, 我们发展了一种简单高效的合成硫化吡唑啉酮的反应, 此方法无需金属催化剂, 利用常见的碘为催化剂就可以
以较高的产率得到目标产物. 为合成含硫化合物提供了一种新的方法.
关键词: C−S键; 碘; 室温; 二硫醚; 硫化
收稿日期: 2017-07-06. 接受日期: 2017-08-14. 出版日期: 2017-10-05.
*
通讯联系人. 电子信箱: wangzulichem@163.com
†
共同第一作者.
基金来源: 国家自然科学基金(21402103, 21772107, 31471808); 中国博士后基金(150030); 青岛农业大学人才基金(631303).
本文的英文电子版由Elsevier出版社在ScienceDirect上出版(http://www.sciencedirect.com/science/journal/18722067).