Intramolecular Oxidation
FULL PAPER
with CH2Cl2/acetone (97:3) afforded an orange band that contained com-
pound 2. Compound 2 was obtained as an orange solid by precipitation
from CH2Cl2/hexane. Yield: 43% yield (78 mg). Crystals suitable for X-
ray diffraction were obtained by slow diffusion of hexane into a concen-
trated solution of 2 in CH2Cl2. 1H NMR (300 MHz, CDCl3, 303 K): d=
contained compound 3c. Compound 3c was obtained as a yellow solid by
precipitation from CH2Cl2/hexane. Yield: 41 mg (25%); 1H NMR
(300 MHz, CDCl3, 303 K): d=7.45–7.35 (m, 5H; CHbenzyl), 7.07 (d, 3J-
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
7.05 (d, 3J
CHimidazole), 5.09 (td, 2J
4.00 (s, 3H; NCH3), 3.75 (m, 2H; NCH2CH2), 3.66 (td, 2J
3J
(H,H)=12 Hz, 1H; CH2CH2OH), 2.60–2.45 (br, 1H; OH), 2.01 (m,
A
ACHTUNGTREN(NUNG H,H)=2 Hz, 1H;
AHCTUNGTRENNUNG
A
ACHTUNGTRENNUNG
A
CHTUNGTRENNUNG
13
1
À
À
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
2H; CH2CH2CH2), 1.81 ppm (s, 15H; C5ACTHUNTRGNEUNG
(CH3)5); 13C{1H} NMR (75 MHz,
C CHTUNGTRENNUNG
À
CDCl3, 303 K): d=151.6 (s; Ir NCN), 124.1 (s; CHimidazole), 121.9 (s;
CTHUNGTRENNUNG
for C16H22ON2IIrH [M+H]+: 655.0798; found: 655.0795; m/z: calcd for
C16H22ON2IIrNa [M+Na]+: 677.0618; found: 677.0610; elemental analysis
calcd (%) for C22H26ON2IIr: C 40.43, H 4.01, N 4.29; found C 40.48, H
3.98, N 4.25.
CHimidazole), 90.3 (s; C
5A
CH2N), 34.2 (s; CH2CH2CH2), 10.8 ppm (s; C5ACTHUNGTRNEUNG(CH3)5); ESI-MS (20 V,
CH3OH): m/z: 595.0 [MÀI]+; elemental analysis calcd (%) for
C17H27ON2I2Ir: C 28.30, H 3.77, N 3.88; found: 28.42, H 3.80, N 3.84.
Compound 3a: 1-(2-Hydroxyethyl)-3-methylimidazolium iodide (63.8 mg,
0.25 mmol), [{IrCp*Cl2}2] (100 mg, 0.125 mmol), Cs2CO3 (491 mg,
1.51 mmol), and KI (250 mg, 1.51 mmol) were heated at 858C in MeOH
(15 mL) for 5 h in a 25 mL flask. The reaction mixture was cooled to
room temperature and filtered. The volatiles were removed under re-
duced pressure. The crude solid was purified by chromatographic
column. Elution with CH2Cl2/acetone (9:1) separated a yellow band that
contained compound 3a. Compound 3a was obtained as a yellow solid
by precipitation from CH2Cl2/hexane. Yield: 43 mg (30%); 1H NMR
Compound 4: 1-(2-Hydroxyethyl)-3-methyltriazolium iodide (32.1 mg,
0.25 mmol), [{IrCp*Cl2}2] (100 mg, 0.12 mmol), Cs2CO3 (491 mg,
1.51 mmol) and KI (250.1 mg, 1.51 mmol) were heated at 858C in MeOH
(15 mL) for 16 h in a 25 mL flask. The reaction mixture was cooled to
room temperature and filtered. The volatiles were removed under re-
duced pressure. The crude solid was purified by chromatographic
column. Elution with CH2Cl2/acetone (9:1) separated a yellow band that
contained compound 4. Compound 4 was obtained as a yellow solid by
precipitation from CH2Cl2/hexane. Yield: 36 mg (25%); 1H NMR
(300 MHz, CDCl3, 303 K): d=8.08 (s, 1H; CHtriazole), 3.99 (s, 3H; NCH3),
(300 MHz, CDCl3, 303 K): d=7.08 (d, 3J
6.86 (d, 3J(H,H)=2 Hz, 1H; CHimidazole), 3.79 (s, 3H; CH3N), 3.58 (AB, 2J-
(A,B)=16 Hz, 1H; NCH2CO), 3.51 (AB, 2J
(A,B)=16 Hz, 1H;
(CH3)5); 13C{1H} NMR (75 MHz, CDCl3,
ACTHNUGNERTN(GNU H,H)=2 Hz, 1H; CHimidazole),
3.62 (AB, 2J(A,B)=16 Hz, 1H; NCH2CO), 3.57 (AB, 2J
ACTHNUGTRENNUGN ACHTUNGTRENNNUG
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
1H; NCH2CO), 1.93 ppm (s, 15H; C5ACTHUNGTRENNNUG
NCH2CO), 1.92 ppm (s, 15H; C
5A
À
À
CDCl3, 303 K): d=220.9 (s; Ir CO), 166.5 (s; Ir NCN), 137.5 (CHtriazole),
À
À
303 K): d=223.5 (s; Ir CO), 162.4 (s; Ir NCN), 122.6 (s; CHimidazole),
95.3 (s; C
5A
AHCTUNGTRENNUNG
(CH3)5); HRMS: m/z: calcd for C15H21ON3IIrH [M+H]+: 580.0438;
116.6 (s; CHimidazole), 94.8 (s; C
N
CH3N), 10.1 ppm (s;
C
(CH3)5); IR (CH2Cl2): n˜ =1628 cmÀ1 (nCO);
found: 580.0436; elemental analysis calcd (%) for C15H21ON3IIr: C 31.14,
H 3.66, N 7.26; found: C 31.10, H 3.70, N 7.22.
HRMS: m/z: calcd for C16H22ON2IIrH [M+H]+: 580.0438; found:
580.0436; elemental analysis calcd (%) for C16H22ON2IIr: C 33.28, H
3.84, N 4.85; found: C 33.29, H 3.92, N 4.70.
Compound 5a: A mixture of Ag2O (58.2 mg, 0.25 mmol) and 1-(3-hy-
droxypropyl)-3-methylimidazolium bromide (55.5 mg, 0.25 mmol) was
stirred in EtOH (10 mL) at room temperature for 2 h in the absence of
light. After this time, the mixture was filtered through Celite.
[{IrCp*Cl2}2] (100 mg, 0.125 mmol) and KI (250 mg, 1.51 mmol) were
added, and the mixture was heated under reflux conditions for 3 h. After
cooling, the mixture was filtered and the solvent was removed at reduced
pressure. The resulting solid was purified by chromatographic column.
Elution with CH2Cl2 afforded an orange band that contained unreacted
[{IrCp*Cl2}2] and a red band that contained compound 5a. Further elu-
tion with CH2Cl2/acetone (9:1) separated a yellow band that contained
compound 3a in 10% yield. Compound 5a was obtained as a red solid
by precipitation from CH2Cl2/hexane. Yield: 15% yield (28 mg).
Compound 3a from 1: Compound 1 (20 mg, 0.03 mmol) was dissolved in
CDCl3 in
a J. Youngs re-sealable NMR spectroscopy tube. Cs2CO3
(29 mg, 0.09 mmol) was added to this solution, and the resulting mixture
was heated at 658C for 3 h. Conversion of compound 1 into compound
1
3a was monitored by H NMR spectroscopy.
Compound 3b: 1-(2-Hydroxyethyl)-3-butylimidazolium iodide (74.3 mg,
0.25 mmol), [{IrCp*Cl2}2] (100 mg, 0.125 mmol), Cs2CO3 (491 mg,
1.51 mmol), and KI (250 mg, 1.51 mmol) were heated at 858C in MeOH
(15 mL) for 5 h in a 25 mL flask. The reaction mixture was cooled to
room temperature and filtered. The volatiles were removed under re-
duced pressure. The crude solid was purified by chromatographic
column. Elution with CH2Cl2/acetone (9:1) separated a yellow band that
contained compound 3b. Compound 3b was obtained as a yellow solid
by precipitation from CH2Cl2/Et2O. Yield: 53 mg (28%). Crystals suitable
for X-ray diffraction were obtained by slow diffusion of Et2O into a con-
centrated solution of 3b in CH2Cl2. 1H NMR (300 MHz, CDCl3, 303 K):
d=7.09 (s, 1H; CHimidazole), 6.89 (s, 1H; CHimidazole), 4.12 (m, 1H; CH2N),
1H NMR (300 MHz, CDCl3, 303 K): d=7.01 (d, 3J
CHimidazole), 6.97 (d, 3J(H,H)=2 Hz, 1H; CHimidazole), 5.96 (d, 2J
18 Hz, 1H; NCH2CO), 4.83 (d, 2J
(H,H)=18 Hz, 1H; NCH2CO), 4.25 (q,
3J
(H,H)=7 Hz, 2H; CH2O), 3.99 (s, 3H; NCH3), 1.83 (s, 15H; C5A(CH3)5),
1.32 ppm (t, 3J(H,H)=7 Hz, 3H; CH2CH3); 13C{1H} NMR (75 MHz,
CDCl3, 303 K): d=169.2 (s; CH2CO), 159.9 (s; Ir NCN), 125.5 (s;
CHimidazole), 123.4 (s; CHimidazole), 90.4 (s; C5A(CH3)5), 61.9 (s; CH2), 56.8 (s;
5A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
A
CHTUNGTRENNUNG
AHCTUNGTRENNUNG
À
3.95 (m, 1H; CH2N), 3.58 (AB, 2J
(AB, 2J
(A,B)=15 Hz, 1H; NCH2CO), 1.92 (s, 15H; C
2H; CH2), 1.60 (m, 2H; CH2), 0.90 ppm (m, 3H; CH3); 13C{1H} NMR
(A,B)=15 Hz, 1H; NCH2CO), 3.52
5A(CH3)5),1.46 (m,
CTHUNGTRENNUNG
CH2), 43.5 (s; NCH3), 14.4 (s; CH2CH3), 10.5 ppm (s; C HCTUGNTREN(NUNG CH3)5); ESI-MS
N
CHTUNGTRENNUNG
(20 V, CH3OH): m/z: 623.0 [MÀI]+; elemental analysis calcd (%) for
À
À
C18H27O2N2I2Ir: C 28.85, H 3.63, N 3.74; found: C 28.92, H 3.60, N 3.71.
(75 MHz, CDCl3, 303 K): d=222.9 (s; Ir CO), 164.7 (s; Ir NCN), 120.4
(s; CHimidazole), 116.4 (s; CHimidazole), 94.6 (s; C5A(CH3)5), 71.7 (s; NCH2CO),
50.6 (s; CH2N), 32.5, 20.2 (s; CH2), 13.9 (s; CH3), 9.9 ppm (s; C5A(CH3)5);
CTHUNGTRENNUNG
Compound 5b: A mixture of Ag2O (58.2 mg, 0.25 mmol) and 1-(3-hy-
droxypropyl)-3-methylimidazolium bromide (55.5 mg, 0.25 mmol) was
stirred in MeOH (10 mL) at room temperature for 2 h in the absence of
light. After this time, the mixture was filtered through Celite.
[{IrCp*Cl2}2] (100 mg, 0.125 mmol) and KI (250 mg, 1.51 mmol) were
added, and the mixture was heated under reflux conditions for 3 h. After
cooling, the mixture was filtered, and the solvent was removed at re-
duced pressure. The resulting solid was purified by chromatographic
column. Elution with CH2Cl2 afforded an orange band that contained un-
reacted [{IrCp*Cl2}2] and a red band that contained compound 5b. Com-
pound 5b was obtained as a red solid by precipitation from CH2Cl2/
hexane. Yield: 34% yield (65 mg). Crystals suitable for X-ray diffraction
were obtained by slow diffusion of hexane into a concentrated solution
CTHUNGTRENNUNG
IR (CH2Cl2): n˜ =1635 cmÀ1 (nCO); ESI-MS (20 V, CH3OH): m/z: 621.0
[M+H]+; HRMS: m/z: calcd for C19H28ON2IIr [M+H]+: 621.0955;
found: 621.0961; elemental analysis calcd (%) for C19H28ON2IIr: C 36.83,
H 4.56, N 4.52; found: C 36.78, H 4.50, N 4.49.
Compound 3c: 1-(2-Hydroxyethyl)-3-benzylimidazolium iodide (82.9 mg,
0.25 mmol), [{IrCp*Cl2}2] (100 mg, 0.12 mmol), Cs2CO3 (491 mg,
1.51 mmol), and KI (250 mg, 1.51 mmol) were heated at 858C in MeOH
(15 mL) for 16 h in a 25 mL flask. The reaction mixture was cooled to
room temperature and filtered. The volatiles were removed under re-
duced pressure. The crude solid was purified by chromatographic
column. Elution with CH2Cl2/acetone (9:1) separated a yellow band that
Chem. Eur. J. 2011, 17, 10453 – 10461
ꢅ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
10459