ACS Catalysis
Research Article
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C6D6, 298 K): δ (ppm) 7.35 (t, JH−H = 7.8 Hz, 2H, CArH),
133.1 (s, CH azole), 130.6 (s, CArH), 124.4 (s, CArH), 123.6 (s,
C4 and C5 carbene, 123.1 (s, CIV azole), 122.2 (s, CH azole),
119.3 (s, CH azole), 117.4 (s, CH azole), 112.9 (s, CH azole),
28.9 (s, CH(CH3)2), 24.7 (s, CH(CH3)2), 23.6 (s, CH(CH3)2).
Anal. Calcd for C34H41CuN4: C, 71.74; H, 7.26; N, 9.84.
Found: C, 71.64; H, 7.40; N, 9.87.
7.10 (d, JH−H = 7.8 Hz, 4H, CArH), 6.39 (s, 2H, H4 and H5
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carbene), 6.36 (s, 1H, CH azole), 2.94−2.77 (m, 4H,
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CH(CH3)2), 1.14 (d, JH−H = 6.8 Hz, 12H, CH(CH3)2), 1.05
(d, JH−H = 6.8 Hz, 12H, CH(CH3)2). 13C-{1H} NMR (126
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MHz, C6D6, 298 K): δ (ppm) 189.2 (s, C2 carbene), 146.6 (s,
CIV), 139.7 (s, CH azole), 137.5 (s, CIV), 130.7 (s, CArH), 128.9
(s, CIV), 124.9 (s, CArH), 122.7 (s, C4 and C5 carbene), 29.4 (s,
CH(CH3)2), 25.4 (s, CH(CH3)2), 24.5 (s, CH(CH3)2). Anal.
Calcd for C30H38BrCuN4: C, 60.24; H, 6.40; N, 9.37. Found: C,
60.18; H, 6.47; N, 9.48.
Synthesis of [N,N′-Bis(2,6-(di-isopropyl)phenyl)imidazol-2-
ylidene](1-phenylethoxy)copper(I), [Cu(1-phenylethoxy)(IPr)],
6. In a glovebox, into a 20 mL scintillation vial, [Cu(OtBu)-
(IPr)] (300 mg, 1.0 equiv) was dissolved in 5 mL of benzene,
and 1-phenylethanol (1.1 equiv) was added. The reaction was
stirred at 25 °C for 16 h. The mixture was concentrated in
vacuo until formation of a precipitate. Hexane (5 mL) was
added. The precipitate was collected by filtration, washed with
hexane (2 × 5 mL), and dried in vacuo to yield 6 as a colorless
[N,N′-Bis(2,6-(di-isopropyl)phenyl)imidazol-2-ylidene](3-
methyl-pyrazol-1-yl)copper(I), [Cu(3-Me-prz)(IPr)], 3d. Reac-
tion between [Cu(Cl)(IPr)] (1 g, 2.05 mmol), 3-methyl-
pyrazole (182 μL, 2.26 mmol), and CsOH (614.9 mg, 4.1
mmol) in THF (20 mL) led to the isolation of 3d as a colorless
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solid in 83% isolated yield (271 mg). H NMR (500 MHz,
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C6D6, 298 K): δ (ppm) 7.52 (d, JH−H = 7.7 Hz, 2H, CArH),
solid in 92% isolated yield (1007 mg). H NMR (500 MHz,
7.24−7.16 (m, 4H, CArH), 7.10 (t, 3JH−H = 7.3 Hz, 2H, CArH),
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CD2Cl2, 298 K): δ (ppm) 7.52 (t, JH−H = 7.7 Hz, 2H, CArH),
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7.05 (d, JH−H = 7.7 Hz, 2H, CArH), 6.25 (s, 2H, H4 and H5
7.34 (d, JH−H = 7.7 Hz, 4H, CArH), 7.22 (s, 2H, H4 and H5
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3
carbene), 5.29 (bs, 1H, CH), 2.55 (sept, JH−H = 7.0 Hz, 4H,
carbene), 7.01 (s, 1H, CH pyrazole), 5.63 (s, 1H, CH
pyrazole), 2.61 (sept, JH−H = 6.8 Hz, 8H, CH(CH3)2), 1.72
CH(CH3)2), 1.37 (d, 3JH−H = 6.3 Hz, 3H, CH3), 1.33 (d, 3JH−H
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= 7.0 Hz, 12H, CH(CH3)2), 1.05 (d, JH−H = 7.0 Hz, 12H,
(s, 3H, CH3), 1.29 (d, JH−H = 6.8 Hz, 12H, CH(CH3)2), 1.23
CH(CH3)2). 13C-{1H} NMR (126 MHz, C6D6, 298 K): δ
(ppm) 184.0 (s, C2 carbene), 156.1 (s, CIV), 146.3 (s, CIV),
135.9 (s, CIV), 131.1 (s, CArH), 128.2 (s, CArH), 126.7 (s,
CArH), 125.5 (s, CIV), 124.8 (s, CArH), 123.0 (s, C4 and C5
carbene), 74.3 (s, CH), 34.0 (s, CH3), 29.5 (s, CH(CH3)2),
25.4 (s, CH(CH3)2), 24.4 (s, CH(CH3)2). Anal. Calcd for
C35H45CuN2O: C, 73.33; H, 7.91; N, 4.89. Found: C, 73.22; H,
8.01; N, 4.93.
(d, JH−H = 6.8 Hz, 12H, CH(CH3)2). 13C-{1H} NMR (126
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MHz, CD2Cl2, 298 K): δ (ppm) 181.1 (s, C2 carbene), 146.0
(s, CIV), 145.9 (s, CIV), 139.3 (s, CH azole), 134.7 (s, CIV),
130.5 (s, CArH), 124.3 (s, CArH), 123.6 (s, C4 and C5 carbene),
101.0 (s, CH azole), 28.8 (s, CH(CH3)2), 24.7 (s, CH(CH3)2),
23.7 (s, CH(CH3)2), 12.9 (s, CH3). Anal. Calcd for
C31H41CuN4: C, 69.83; H, 7.75; N, 10.51. Found: C, 69.69;
H, 7.75; N, 10.67.
[N,N′-Bis(2,6-(di-isopropyl)phenyl)imidazol-2-ylidene](3-
bromo-pyrazol-1-yl)copper(I), [Cu(3-Br-prz)(IPr)], 3e. Reac-
tion between [Cu(Cl)(IPr)] (1 g, 2.05 mmol), 3-bromo-
pyrazole (332.2 mg, 2.26 mmol), and CsOH (614.9 mg, 4.1
mmol) in THF (20 mL) led to the isolation of 3e as a colorless
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
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S
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solid in 90% isolated yield (1103 mg). H NMR (500 MHz,
Experimental details, characterization data, X-ray crys-
tallography data for 3a−3f and 6 (PDF)
C6D6, 298 K): δ (ppm) 7.45 (s, 1H, CH pyrazole), 7.16 (t,
3JH−H = 7.7 Hz, 2H, CArH), 7.02 (d, 3JH−H = 7.7 Hz, 4H, CArH),
6.28 (s, 1H, CH pyrazole), 6.25 (s, 2H, H4 and H5 carbene),
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3
AUTHOR INFORMATION
Corresponding Author
ORCID
2.53 (sept, JH−H = 6.9 Hz, 4H, CH(CH3)2), 1.34 (d, JH−H
=
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6.9 Hz, 12H, CH(CH3)2), 1.05 (d, JH−H = 6.9 Hz, 12H,
CH(CH3)2). 13C-{1H} NMR (126 MHz, C6D6, 298 K): δ
(ppm) 182.6 (s, C2 carbene), 146.3 (s, CIV), 141.5 (s, CH
azole), 135.3 (s, CIV), 131.4 (s, CArH), 125.0 (s, CArH), 123.5
(s, C4 and C5 carbene), 123.0 (s, CIV azole), 105.0 (s, CH
azole), 29.6 (s, CH(CH3)2), 25.7 (s, CH(CH3)2), 24.4 (s,
CH(CH3)2). Anal. Calcd C30H38BrCuN4: C, 60.24; H, 6.40; N,
9.37. Found: C, 60.18; H, 6.31; N, 9.38.
[N,N′-Bis(2,6-(di-isopropyl)phenyl)imidazol-2-ylidene]-
(indazol-1-yl)copper(I), [Cu(ind)(IPr)], 3f. Reaction between
[Cu(Cl)(IPr)] (1 g, 2.05 mmol), indazole (267 mg, 2.26
mmol), and CsOH (614.9 mg, 4.1 mmol) in THF (20 mL) led
to the isolation of 3f as a colorless solid in 94% isolated yield
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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(1098 mg). H NMR (500 MHz, CD2Cl2, 298 K): δ (ppm)
The authors gratefully acknowledge the Royal Society
(University Research Fellowship to C.S.J.C.), the Spanish
MINECO (CTQ2014-59832-JIN), and EU (FEDER fund
UNGI08-4E-003) for funding.
7.77 (d, 5JH−H = 1.1 Hz, 1H, CH azole), 7.59 (t, 3JH−H = 7.8 Hz,
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2H, CArH), 7.46 (dt, JH−H = 7.8 Hz, JH−H = 1.1 Hz, 1H, CH
azole), 7.39 (d, 3JH−H = 7.8 Hz, 4H, CArH), 7.27 (s, 2H, H4 and
H5 carbene), 6.82−6.76 (m, 1H, CH azole), 6.74−6.69 (m, 1H,
CH azole), 6.32 (d, 3JH−H = 8.3 Hz, 1H, CH azole), 2.67 (sept,
3JH−H = 6.8 Hz, 8H, CH(CH3)2), 1.31 (d, 3JH−H = 6.8 Hz, 12H,
REFERENCES
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(1) For a selected review on copper(I)−NHC applications, see:
(a) Lazreg, F.; Nahra, F.; Cazin, C. S. J. Coord. Chem. Rev. 2015, 293−
294, 48−79. (b) Zhang, L.; Hou, Z. Pure Appl. Chem. 2012, 84, 1705−
1712. (c) Zhang, L.; Hou, Z. Chem. Sci. 2013, 4, 3395−3403.
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CH(CH3)2), 1.26 (d, JH−H = 6.8 Hz, 12H, CH(CH3)2). 13C-
{1H} NMR (126 MHz, CD2Cl2, 298 K): δ (ppm) 181.0 (s, C2
carbene), 150.0 (s, CIV), 146.0 (s, CIV azole), 134.7 (s, CIV),
8182
ACS Catal. 2017, 7, 8176−8183