1 synthesis and characterization of au nanoparticles-supported n-heterocyclic carbene copper(i)...
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1
Synthesis and Characterization of Au Nanoparticles-Supported N-Heterocyclic Carbene Copper(I) Complex. The Catalytic Applicatio
n on Huisgen Cycloaddition Reactions
學生：莊雲婷指導教授：于淑君 博士
2010 /07 / 30Department of Chemistry & Biochemistry
Chung Cheng University
2
Phosphine Ligand
Phosphines are electronically and sterically tunable.
Expensive.
Air sensitive.
P-C, P-OR cleavage under high temperature.
Metal leaching.
Chemical waste.
P P PPO
OO
P(Bu)3 P(OiPr)3 P(Me)3 P(o-tolyl)3
3
N-Heterocyclic Carbenes
NHCs are stronger σ-donor and weaker π-acceptor than the most electron rich phosphines.
NHCs can be useful spectator ligands, because they are sterically and electronically tunable.
NHCs can promote a wide series of catalytic reactions.
NHCs have advantages over phosphines and offer catalysts with better air-stability.
[M]
4
N-Heterocyclic Carbenes as Ligands- In the early 90's NHC were found to have bonding properties similar to trialklyphosphanes and alkylphosphinates.
- compatible with both high and low oxidation state metals
- examples:
- reaction employing NHC's as ligands:
Herrmann, W. Angew. Chem. Int. Ed. 2002, 41, 1290-1309.
Herrmann, W. A.; Öfele, K; Elison, M.; Kühn, F. E.; Roesky, P. W. J. Organomet. Chem. 1994, 480, C7-C9.
N NMe Me
W
COCOOCCOOC V
NHCCHN
NHCCHNCl
ClTi ClCl
ClCl
NN
N N
Me Me
MeMe
Re OO
OMe
N NMe Me Ru
PCy3
Ph
NNMesMes
ClCl
5
The Catalytic Applications of CuI
O-arylation of Phenols
Kharasch-Sosnovsky Reaction (Allylic Oxidations of Olefins)
S-arylation of Thiols
N-arylation of Amines (Buchwald-Hartwig Reaction)
Hydrosilylation of Ketones
Heck reaction
Oxidation of Alcohols
Substitution Reaction
Epoxidation Reaction
Reductive Aldol Reaction
1,3-dipolar cycloaddition
Carl Glaser. Berichte der deutschen chemischen Gesellschaft 1869. 2, 422–424.
Sonogashira Reaction
CuCl, O2
NH4OH, EtOH
6
Drawbacks of Traditional Copper-Mediated Reactions
insoluble in organic solvents - heterogeneous
harsh reaction conditions - high temperatures around 200 °C - strong bases required - toxic solvent such as HMPA - long reaction times - the yields are often irreproducible
structure not clear
Girard, C. Org. Lett., 2006. 1689-1692
7
Catalyst Supported onto Au NPs Surface
soluble metal complex
functional groups
coordinationl ligands
spacer linker
catalyst
Au NPs have been known not only to possess solid surfaces resembling the (1 1 1) surface of bulk gold but also to behave like soluble molecules for their dissolvability, precipitability, and redissolvability.
Lin, Y.-Y; Tsai, S.-C.; Yu, S. J. J. Org. Chem. 2008, 73, 4920-4928.
Au NPs with controllable solubility
8
NN (CH2)6 S
Cl
2
+ HAuCl4
NaBH4NN (CH2)6 SH
Cl
Aun
Photographs of the obtained solutions of the 1-modified gold NPs after addition of (a) HCl (b) HBr (c) HBF4 (d) HI (e) HPF6.
Chujo.Y. J. Am. Chem. Soc. 2004, 126, 3026-3027
Gold Nanoparticles Modified with Ionic Liquid
(a) (e)
9
Rolf Huisgen was the first to understand this organic reaction at 1961.
1,3-Dipolar cycloaddition between azide and alkyne to give a 1,2,3-triazole
K. Barry Sharpless and co-workers defined it as “a set of powerful, highly reliable, and selective reactions for the rapid synthesis of useful new compounds and combinatorial libraries”
R1NNN + R2N
NN
R1
R2
NN
NR1
R2
azide alkyne1,4-disubstituted
triazoles1,5-disubstituted
triazoles
+
Sharpless, K. B. Angew. Chem., Int. Ed. 2001, 40, 2004-2021
Azide-Alkyne Huisgen Cycloaddition
Anke Cwiklicki, A. Arch. Pharm. Pharm. Med. Chem. 2004, 337, 156−163
Huisgen, R. .Angew. Chem. Int. Ed. 1961. 11. 633–645.
10Fokin, V. V.; Jia, G.; Lin, Z. J. Am. Chem. Soc. 2008. 130. 8923–8930
2 mol % cat.Rt, 30 min
Yield = 63-97 %
Tornøe, C. W.; Christensen, C.; Meldal, M. J. Org. Chem. 2002, 67, 3057-3064
(i) 2 eq 2-Azido-2-methylpropionic acid, 50 eq DIPEA, 2 eq CuI.(ii) 0.1 M NaOH (aq).
First Metal Catalyzed Azide-Alkyne Cycloaddition
Copper
Ruthenium
11
Sharpless, K. B. Angew. Chem. Int. Ed. 2002, 41, 2596-2599
Reported CuI Catalyzed Azide-Alkyne Cycloaddition
Reduction of CuII Salt
Oxidation of Cu Metal
Ligand Assisted CuI Salt
+1 mol % Cu(CH3CN)4PF6
H2O/t-BuOH = 1:2, rt, 24h
NN
N
84 %
N N
N BnN
3
1 mol %
N3
O+ N
NN
CuSO4‧ 5H2O, 1 mol%sodium ascorbate, 5 mol%
H2O/BuOH, 2:1, RT, 8h
NN
NO
+10 mol % Cu NPs
THF, 65oC,10 min
NN
N
98 %
N3
Fokin, V. V.Org. Lett. 2004, 6, 2853-2855
Alonso, F. Eur. J. Org. Chem. 2010, 1875-1884.
TOF= 2.3 h-1
TOF= 59 h-1
TOF= 3.5 h-1
12
Reported CuI Catalyzed Azide-Alkyne Cycloaddition
NHC-CuI
Supported CuI Salt on Solid Phase
N3 +N
NN0.8 mol % (SIMes)CuBr
neat, rt, 20 min
98 %
Nolan, S. P. Chem. Eur. J. 2006, 12, 7558-7564.
CatalystCu loading
(mol %)Temp.
(oC)Time(hr)
Yield(%)
TOF(h-1)
ref
Cu(OH)x/TiO2 1.5 60 0.16 99a 396 Chem. Eur. J. 2009, 10464
CuNPs/AlO(OH) 3 rt 6 94b 5 J. Org. Lett. 2008. 497
CuI-Zeolite 10 rt 15 83c 0.6 J. Org. Lett. 2007, 883
SiO2-NHC-CuI 1 rt 0.5 93d 186 Tetrahedron, 2008, 10825
+N N
NN3
TOF= 368 h-1
13
Reported Mechanism for CuI-CatalyzedAzide-Alkyne Cycloaddition
Nolan, S. P. Angew. Chem. Int. Ed. 2008, 47, 8881 –8884
14
Motivation
Using NHCs to replace phosphines in organomatallic catalysis.
Base on economic standpoint, copper metal is much more
Inexpensive than palladium catalyst . - PdCl2 $4805.00(150g) ReagentPlus® (Aldrich) - CuCl $206.00(100g) ReagentPlus® (Aldrich)
Synthesis of NHC-Cu(I) complexes with well-defined structures.
Greener catalysis – microwave and solventless conditions.
To design an easily recovered and effectively recycled Au NPs supported copper(I) complex catalyst.
15
hmim = 1-hexyl-3-methylimidazolium
Preparation of CuI Complex Catalyst
Br
NN
65 oC, 12 hyield = 95 %
NN
Br
CuI, t-BuONa
THF reflux, 24hyield = 96 %
(hmim)HBr(1)
NN
CuI(hmim)(2)
Cu
I
Preparation of (HS-hmim)HPF6
Br Br
NN
DMF, 65 oC, 16 hyield = 95 %
NN Br
Br
1. CS(NH2)2, EtOH reflux, 16 h2. NaOH, 20oC, 3 min3. HCl, 20oC, 20 min
Yield = 70 %
NN SH
Br
KPF6, H2O
0oC, 30 minyield = 53 %
NN SH
PF6
(HS-hmim)HPF6(3)
16
TOAB = tetra-octyl ammonium bromideSR = Octane thiol
Au(SR) size : 2.4 0.39 nm
Synthesis of Octanethiol Protected Au NPs
HAuCl4 -4H2O
[CH3(CH2)7]4N+Br-
CHCl3, 1 h CHCl3. 15 min
NaBH4
H2O, 8 min S
S
SAu
Au(SR) (4)
SH
SRTOAB
17
IL = (S-hmim)(HPF6)
Au(SR)(IL) size : 2.04 0.7 nm
Synthesis of Au NPs Modified with Ionic Liquid
S N
SAu N
PF6S
NN
PF6Au(SR)m(IL)n
(5)
S
S
SAu
Au(SR) (4)
NN SH
PF6
(3)
THF, 40 oC, 4 h
18
HS-CH2-
HS-CH2-
-CH3
-CH3
-CH3
DMSO
(4)
SCH2
CH3
S
H2C CH3
Au
CH3
H2C
HS
SHCH2
N N
PF6
(3)
SCH2 N
S
H2C
Au
CH3
NPF6
(5)
CHCl3
CHCl3
DMSO
19
S
S N
SAu
N
PF6S
NN
PF6
S
SAu
NN SH
PF6
S N
SAu
NS
N
CuI, t-BuONaCu
Cl
N
CuCl
Solvent = DMF CH3CN, THF
CuCI, t-BuONa
Solvent = CH3CN,
Design of Au(SR)(IL)(ILCu) (6)
20
ILCu = S-hmim-CuCl
Au(SR)(IL)(ILCu) size : 1.63 0.32 nm
Synthesis of Au NPs Supported NHC-CuI Complex
S N
SAu N
PF6S
NN
PF6Au(SR)m(IL)n
(5)
CuCl, t-BuONa
CH3CN, 60 oC, 24 hS N
SAu
NS
N
Cu
Cl
Au(SR)x(IL)y(ILCu)z(6)
N
CuCl
21
-CH2-Hb
HbHa
-CH2-
-CH3
-CH3
*
*
#
#
H2O
H2O
DMSO
DMSO
NNH3CH2C
BrHa
Hb Hb
(hmim)HBr(1)
NNH3CH2C
Cu
I
Hb Hb
CuI(hmim)(2)
1H NMR Spectra of (hmim)HBr (1) & CuI(hmim) (2)
22
1H NMR Spectra of Au(SR)(IL) (5) & Au(SR)(IL)(ILCuCl) (6)
*d-DMSO
*d-DMSO#H2O
#H2O
HbHa
-CH2-
-CH3
Hb
-CH2-
-CH3
-CH3
-CH3
S H2C
N
SAu
CH3
N CH3
Cu
Cl
HbHb
Au(SR)0.09(ILCu)1(6)
S H2C
N
SAu
CH3
N CH3
PF6
Ha
Hb Hb
Au(SR)0.17(IL)1(5)
23
13C NMR Spectra of Au(SR)(IL) (5) & Au(SR)(IL)(ILCuCl) (6)
136.3 ppm
182.6 ppm
*DMSO
*DMSO
123.3 ppm121.9 ppm
123.6 ppm122.1 ppm
S
N
SAu
C CN
C
PF6
H
Au(SR)0.17(IL)1(5) H H
S
N
SAu
C CN
C
Cu
Cl
Au(SR)0.09(ILCu)1(6) H
H
24
IR Spectra of Ligand and NHC-CuI Series
CuI(hmim) (2)
(hmim)HBr (1)
Au(SR)(IL)(ILCu) (6)
Au(SR)(IL) (5)
4000 3500 3000 2500 2000 1500 10000
20
40
60
80
100
120
140
160
T (
%)
Wavenumber (cm-1)
(S-hmim)HPF6 (3)
1573
1636
1575
1677
1167
1229
1169
1218
2589
25
Ni
EDS of Au(SR)(IL)(ILCuCl) (6)
Element Weight% Atomic%
C 25.56 72.89
Ni 25.13 14.67
Cu 10.60 5.71
Au 38.71 6.73
S
N
SAu
N
CuCl
26
XPS of Au(SR)(IL)(ILCuCl) (6)
92 90 88 86 84 82 80 780
200
400
600
800
1000
1200
Inte
nsity
(co
unts
/sec
)
Binding Energy(eV)
Au
87.5 eV
4f5/2
4f7/2
83.7 eV
Au
83.8 eV 87.5 eV
Brust, M. J. Chem. Soc. Chem. Commun. 1994, 801-802.
Au
27
XPS of Au(SR)(IL)(ILCuCl) (6)
965 960 955 950 945 940 935 930
Inte
nsi
ty
Binding Energy (eV)
952.6
2p3/2
2p1/2
Cu 932.8
Frost, D. C. Mol. Phys, 1972. 24. 861-877.
Binding Energy Cu(2p1/2) Cu(2p3/2)
CuClPPh3 953.2 eV 933.5 eV
CuCl(PPh2H)3 953.3 eV 933.4 eV
CuCl(PPh3)(o-phen) 952.4 eV 932.4 eV
28
CuI(hmim) (2) Catalyzed Huisgen Cycloaddition – Solvent Effect
Condition: Benzyl azide = 1 mmol, phenyl acetylene = 1.2 mmol. solvent = 0.25 mL, rt, 1 mol% (hmim)CuI. The conversion were determined by 1H NMR
29
CuI(hmim) (2) Catalyzed Huisgen Cycloaddition
Nolan, S. P. Angew. Chem. Int. Ed. 2008, 47, 8881 –8884
Condition: Benzyl azide = 1 mmol, phenyl acetylene = 1.2 mmol. solvent = 0.25 mL, rt, 0.05 mol% (hmim)CuI. The conversion were determined by 1H NMR
TOF(h-1)
333 2225 5062
27 %
30Condition: azide = 1 mmol, phenyl acetylene = 1.2 mmol. neat, rt, 1 mol% (hmim)CuI. The conversion were determined by 1H NMR
CuI(hmim) (2) Catalyzed Huisgen Cycloaddition
31
CuI(hmim) (2) Catalyzed Huisgen Cycloaddition
Condition: azide = 1 mmol, 1-nonyne = 1.2 mmol. neat, rt, 1 mol% (hmim)CuI. The conversion were determined by 1H NMR
32
CuI(hmim) (2) Catalyzed Huisgen Cycloaddition
33
Alkyne:
Azide:
N3
O2N
N3
Br
N3
N3 N3N3
N3
>
≅ >
> >>
Cycloaddition Reactivity of Various Substrates
pKa = 19 pKa = 25
>
34
CuI Contents of Au(SR)x(LR)y(ILCu)z (6) Determined by NMR Spectroscopy
I
H3COH
H
H
H
2H2H2H
3H
ILCu : iodoanisole = (1-0.1648) : 0.1648 = ILCu : 2.245 x 10-6
ILCu = 1.137 x 10-5 mol
ILCu : SR = (1-0.1648) : 0.1080 = 1:0.13 Au(SR)x(LR)y(ILCu)z = AuSR0.13LR0Cu1
d6-DMSO
Au(SR)(ILCu) : 8 mg
4-iodoanisole : 2.245 x 10-6 mol
S
N
SAu
CH3
N
Cu
Cl
HH
Au(SR)0.13(ILCu)1(6)
35
AuILCuCl (6) Catalyzed Huisgen Cycloaddition
Conversion were determined by 1H NMR. Reaction condition : 10 mg AuSR0.38LR0Cu1.
benzyl azide = 1.8 mmol. phenyl acetylene = 2.15 mmol. solvent = 0.4 mL
36
AuILCuCl (6) Catalyzed Huisgen Cycloaddition
Conversion were determined by 1H NMR.
37
Various Copper Salts and Their Cycloaddition Reactivities
Reactivity : NHC-CuI > NHC-CuCl
Conversion were determined by 1H NMR. Reaction condition : benzyl azide = 2.8 mmol. phenyl acetylene = 3.4 mmol. solvent = 0.75 mL. a.1,4-product and 1,5-product is mixed.
38
Competative Substrate Binding on Au Surface v.s. Thiol Poisoning
Decrease reactivity : free octanethiol > Au NPs supported-octanethiol
Conversion were determined by 1H NMR. Reaction condition : 10 mg CuCl(hmim), benzyl azide = 2.8 mmol. phenyl acetylene = 3.4 mmol. CHCl3= 2 mL. (4) = 2.33x10-6 mol octanethiol / mg
39
The Surface Thiol Ratio on AuILCuCl v.s. Catalytic Reactivity
Increase (x+y)/z , decrease reactivity
Conversion were determined by 1H NMR. Reaction condition : 1 mol% Cu of (6). benzyl azide = 1 eq. phenyl acetylene = 1.2 eq. solvent = 0.25 mL.
Au(SR)x(LR)y(Cu)z
40
Saturation of Au Surface with Alkyne
Au
CuCl
41
Microwave-Assisted (6) Catalyzed Huisgen Cycloaddition
microwave thermal
Kappe, C. O. Angew. Chem. Int. Ed. 2004, 43, 6250-6284.
Solvent Time (min)Conversion
(%)
[Bmim][Br] 0.5 65
DMSO
1.5 4
2 24
3 99
CH3CN0.5 8
1 54
+
N3
1 mol % Au(SR)0.19(IL)0.57(ILCu)1 (6)
600 W
NN
N
Conditions: Benzyl azide (0.8 mmol), alkyne (0.96 mmol), Solvent = 0.15 mL. Conversion detected by 1H NMR
42
Microwave-Assisted (6) Catalyzed Huisgen Cycloaddition
Conversion were determined by 1H NMR. Reaction condition : cat.(6) = 10 mg, azide = 1 eq. phenyl acetylene = 1.2 eq. solvent = 2 drop [Bmim][PF6].
43
Conclusions
We have successful synthesized Au NPs- supported
NHC-CuI complex (6) and characterized it by using 1H- and 13C-NMR, TEM, IR, EDS and XPS.
We have successfully demonstrated the catalyticactivity of the CuI complex in both the molecular and supported forms for the Huisgen cycloaddition.
Further acceleration on the rate of the CuI catalyzed
Huisgen cycloaddition was achieved undermicrowave irradiation conditions.