Supporting information
Catalytic oxygenation of various monophenols by copper(I) complexes with
bis(pyrazolyl)methane ligands: Differences in reactivity
JESSICA NADINE HAMANN, REBECCA SCHNEIDER and FELIX TUCZEK*
Contents:
I.
Materials and Techniques ................................................................................................... 1
II.
Syntheses of BPM, mBPM and dmBPM ...................................................................... 2
III.
Syntheses of the copper(I) complexes ............................................................................. 2
IV.
UV/Vis spectroscopy....................................................................................................... 3
V.
NMR spectroscopy ...................................................................................................... 144
VI.
Mass spectrometry......................................................................................................... 15
I.
Materials and Techniques
All starting materials were ordered by Sigma-Aldrich Co. LLC in reagent grade. Solvents
used (acetone, acetonitrile, dichloromethane, diethyl ether, tetrahydrofuran) are reagent grade
and have been purified by refluxing over drying agents and distilled under nitrogen
atmosphere. Oxygen sensitive syntheses were performed by using Schlenk techniques and
stored under nitrogen after preparation. NMR spectra were recorded at 300 K on a Bruker
Avance 400 Pulse Fourier Transform spectrometer operating at a
400.13 MHz and a
1
H frequency of
13
C frequency of 100.6 MHz; TMS was used as a standard. Elemental
analyses were performed using a Euro Vector CHNS-O-element analyser (Euro EA 3000): In
a stream of dioxygen, prepared assays were burned in tin vessels. Optical absorption spectra
were recorded in solution on an Agilent 8453 spectrometer by using a quartz cell with length l
= 1 mm. Furthermore, optical absorption spectra at low temperatures were recorded in
solution on an Agilent Cary 5000 spectral photometer using a CryoVAC KONTI cryostat with
1
quartz cell length 1 cm. Mass spectra (MALDI-TOF-MS) were recorded using a Bruker Biflex
III spectrometer.
Geometric optimizations of structures were carried out using the LanL2DZ basis-set with the
B3LYP functional. The calculations were performed with Gaussian09 on a NEC SX-9 array
processor.[1]
II.
Syntheses of BPM, mBPM and dmBPM
Synthesis of BPM, mBPM and dmBPM. For the synthesis of the ligands, a known synthesis
according to Khlebnikov et al. was used [2]. Elemental analyses and NMR data were obtained
in accordance with the literature.
Anal. Calcd for C7H8N4 (%): C, 56.7; H, 5.4; N, 37.8. Found: C, 56.4; H, 5.5; N, 37.4.
Anal. Calcd for C9H12N4 (%): C, 61.3; H, 6.9; N, 31.8. Found: C, 61.0; H, 7.2; N, 31.4.
Anal. Calcd for C11H16N4 (%): C, 64.7; H, 7.9; N, 27.4. Found: C, 64.4; H, 8.0; N, 27.0.
III.
Syntheses of the copper(I) complexes
Synthesis of [CuIBPM(NCCH3)2]PF6. The synthesis was performed under argon
atmosphere.
A
solution
of
372 mg
(1.00 mmol)
tetrakis(acetonitrile)copper(I)hexafluorophosphate dissolved in 8 mL acetonitrile was dropped
into a solution of 149 mg (1.00 mmol) BPM in 5 mL acetonitrile. The colorless solution was
stirred for 30 min at ambient temperature followed by evaporated to dryness. A colorless solid
was obtained with a yield of 307 mg (70%, 0.71 mmol). Anal. Calcd (%) for C11H14N6CuPF6:
C, 30.1; H, 3.2; N, 19.2. Found: C, 29.7; H, 3.4; N, 19.3. 1H NMR (400 MHz, acetone-d6):
δH = 8.00 (d, 2H, pzH-3, pzH-3’), 7.70 (d, 2H, pzH-5, pzH-5’), 6.60 (s, 2H, -CH2), 6.36 (t,
2H, pzH-4, pzH-4’), 2.14 (s, 6H, -NCCH3) ppm.
13C-NMR
(100.6 MHz, acetone-d6):
δC = 142.3 (C-3, C-3’), 132.3 (C-5, C-5’), 117.3 (-NCCH3), 106.8 (C-4, C-4’), 63.2 (-CH2),
0.9 (-NCCH3) ppm.
Synthesis of [CuImBPM(NCCH3)2]PF6. The synthesis was performed under argon
atmosphere. A solution of 372 mg (1.00 mmol) tetrakis(acetonitrile)copper(I)hexafluorophosphate dissolved in 8 mL acetonitrile was dropped into a solution of 176 mg (1.00 mmol)
2
BPM in 6 mL acetonitrile. The colorless solution was stirred for 30 min at ambient
temperature followed by evaporated to dryness. A colorless solid was obtained with a yield of
298 mg (64%, 0.64 mmol). Anal. Calcd (%) for C13H18N6CuPF6: C, 33.5; H, 3.9; N, 18.0.
Found: C, 33.2; H, 3.6; N, 18.3. 1H NMR (400 MHz, acetone-d6): δH = 7.98 (d, 1H, pzH-5),
7.83 (d, 1H, pzH-5’), 6.39 (s, 2H, -CH2), 6.16 (t, 2H, pzH-4, pzH-4’), 2.46 (s, 3H, -CH3), 2.40
(s, 3H, CH3), 2.16 (s, 6H, -NCCH3) ppm. 13C NMR (100.6 MHz, acetone-d6): δC = 151.3 (C3, C-3’), 132.9 (C-5, C-5’), 117.5 (-NCCH3), 106.5 (C-4, C-4’), 60.1 (-CH2), 12.7 (-CH3),
10.1 (-CH3), 1.0 (-NCCH3) ppm.
Synthesis of [CuIdmBPM(NCCH3)2]PF6. The synthesis was performed under argon
atmosphere. A solution of 372 mg (1.00 mmol) tetrakis(acetonitrile)copper(I)hexafluorophosphate dissolved in 8 mL acetonitrile was dropped into a solution of 204 mg (1.00 mmol)
BPM in 8 mL acetonitrile. The colorless solution was stirred for 30 min at ambient
temperature followed by evaporated to dryness. A colorless solid was obtained with a yield of
300 mg (61%, 0.60 mmol). Anal. Calcd (%) for C15H22N6CuPF6: C, 36.4; H, 4.5; N, 17.0.
Found: C, 36.0; H, 4.2; N, 17.3. 1H NMR (400 MHz, acetone-d6): δH = 6.16 (s, 2H, -CH2),
5.98 (s, 2H, pzH-4, pzH-4’), 2.37 (s, 6H, -CH3), 2.20 (s, 6H, -NCCH3), 2.08 (s, 6H, -CH3)
ppm. 13C NMR (100.6 MHz, acetone-d6): δC = 150.4 (C-3, C-3’), 141.7 (C-5, C-5’), 117.7 (NCCH3), 106.5 (C-4, C-4’), 57.0 (-CH2), 12.7 (-CH3), 9.9 (-CH3), 0.9 (-NCCH3) ppm.
IV.
UV/Vis spectroscopy
General procedure: Catalytic oxygenation reactions were performed at room temperature
and to this end a 500 µM solution of the respective copper(I) complex in dichloromethane was
prepared and 50 eq. of the external substrate and 100 eq. of triethylamine were added.
Subsequent oxygenation at ambient temperature was found to result in the formation of orthoquinones, as indicated by absorption bands in the range of 390 – 418 nm.
3
b)
a)
c)
Oxygenation of 2,4-di-tert-butyl-phenol
Figure S1. Oxygenation of 2,4-DTBP-H for 8 h with a) [CuIBPM(NCCH3)2]PF6,
b) [CuImBPM(NCCH3)2]PF6, c) [CuIdmBPM(NCCH3)2]PF6, l = 1 mm.
4
UV/Vis measurements at low temperatures
Figure S2. Absorption spectra of the Cu2O2 complex. Dashed line: UV/Vis spectrum of a
2.5 mM solution of [CuIdmBPM(NCCH3)2]PF6 in acetone before oxygenation; solid line:
UV/Vis spectrum after oxygenation of [CuIdmBPM(NCCH3)2]PF6 in acetone at – 90 °C.
Inset: TD-DFT calculated UV/Vis spectrum and geometry-optimized structure of the
dmBPM peroxo intermediate using B3LYP/LANL2DZ [1].
5
Oxygenation of 3-tert-butyl-phenol
a)
b)
c)
Figure S3. Oxygenation of 3-TBP-H for 8 h with a) [CuIBPM(NCCH3)2]PF6,
b) [CuImBPM(NCCH3)2]PF6, c) [CuIdmBPM(NCCH3)2]PF6, l = 1 mm.
6
Oxygenation of phenol
a)
b)
c)
Figure S4. Oxygenation of phenol for 6 h with a) [CuIBPM(NCCH3)2]PF6,
b) [CuImBPM(NCCH3)2]PF6, c) [CuIdmBPM(NCCH3)2]PF6, l = 1 mm.
7
Oxygenation of N-acetyl-tyrosine ethyl ester
a)
b)
c)
Figure S5. Oxygenation of NATEE for 2 h with a) [CuIBPM(NCCH3)2]PF6,
b) [CuImBPM(NCCH3)2]PF6, c) [CuIdmBPM(NCCH3)2]PF6, l = 1 mm.
8
Figure S6. Oxygenation of NATEE for 24 h with [CuIBPM(NCCH3)2]PF6; decrease of the
absorption band and shifting to lower wavelength, l = 1 mm.
9
Oxygenation of N-acetyl-L-tyrosine ethyl ester:
The measured NMR spectra after working the oxygenation solution results the signals for the
corresponding secondary alcohol of the ester function as by-product that is formed during the
oxygenation. Measuring a UV/Vis spectrum after working up results no characteristic
absorption band of the quinone.
Figure S7. Measured 1H-NMR spectrum of the oxygenation solution after working up with
hydrochloric acid. The doublet at 6.05 ppm indicates that the ester function was converted to
the hemiacetal.
10
Oxygenation of 4-methoxyphenol
b)
a)
c)
Figure S8. Oxygenation of 4-methoxyphenol with a) [CuIBPM(NCCH3)2]PF6 for 4 h,
b) [CuImBPM(NCCH3)2]PF6 for 1 h, c) [CuIdmBPM(NCCH3)2]PF6 for 1 h, l = 1 mm.
11
Oxygenation of 4-methylphenol
a)
b)
c)
Figure S9. Oxygenation of 4-methylphenol for 6 h with a) [CuIBPM(NCCH3)2]PF6,
b) [CuImBPM(NCCH3)2]PF6, c) [CuIdmBPM(NCCH3)2]PF6, l = 1 mm.
12
Figure S10. Oxygenation of 4-MeP-H for 24 h with [CuIBPM(NCCH3)2]PF6; decrease of the
absorption band at 655 nm, l = 1 mm.
13
V.
NMR spectroscopy
Quenching of oxygenation solutions with HCl. After 30 minutes of oxygenation reaction a
small amount of solutions were diluted to a 25 μM solution and were quenched with 6 M
hydrochloric acid extracted with dichloromethane to eliminate the copper ions and were
evaporated in vacuo. Obtained H NMR data are listed:
Oxygenation of 2,4-DTBP-H:
1
H-NMR (400 MHz, CDCl3): DTBQ: δH = 6.94 (d, 1H, H-4), 6.22 (d, 1H, H-6), 1.27 (s, 9H,
-(CH3)3), 1.22 (s, 9H, -(CH3)3) ppm.
C-NMR (100.6 MHz, CD3Cl): DTBQ: δC = 181.2 (C-1), 180.1 (C-2), 163.4 (C-5), 150.0
13
(C-3), 133.5 (C-4), 122.1 (C-6), 36.0 (-C(CH3)3), 35.5 (-C(CH3)3), 29.2 (-C(CH3)3), 27.9
(-C(CH3)3) ppm.
Oxygenation of 3-TBP-H:
1
H-NMR (400 MHz, CDCl3): TBQ: δH = 7.26 (d, 1H, H-5), 6.30 (s, 1H, H-3), 6.06 (d, 1H,
H-6), 1.36 (s, 9H, -(CH3)3) ppm.
C-NMR (100.6 MHz, CD3Cl): TBQ: δC = 181.6 (C-1), 179.1 (C-2), 158.0 (C-4), 139.4 (C-
13
5), 129.6 (C-3), 128.4 (C-6), 34.3 (-C(CH3)3), 31.6 (-C(CH3)3) ppm.
Oxygenation of phenol:
1
H-NMR (400 MHz, CDCl3): BzQ: δH = 7.54 (t, 2H, H-5, H-4), 6.33 (d, 2H, H-6, H-3) ppm.
C-NMR (100.6 MHz, CD3Cl): BzQ: δC = 178.0 (C-1, C-2), 152.1 (C-6, C-3), 130.5 (C-4,
13
C-5) ppm.
Oxygenation of 4-methoxyphenol:
1
H-NMR (400 MHz, CDCl3): 2-hydroxy-5-methoxy-1,4-benzoquinone: δH = 6.78 (s, 2H, H-6,
H-3), 3.76 (s, 3H, -OCH3) ppm.
C-NMR (100.6 MHz, CDCl3): 2-hydroxy-5-methoxy-1,4-benzoquinone: δC = 181.5 (C-4),
13
179.1 (C-1), 158.3 (C-5), 106.4 (C-3, C-6), 58.2 (-OCH3) ppm.
14
VI.
Mass spectrometry
N-acetyl-L-dopa ethyl ester
(MALDI, m/ z): 268.1 [M + H]
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15