760
Can. J. Chem. Vol. 91, 2013
Fig. 5. Molecular structure of 11 with hydrogen atoms omitted for
clarity. Thermal ellipsoids are shown at 50% probability. Selected
bond lengths (Å])and angles (°): Pd(1)–C(11) 1.969(2), Pd(1)–N(3) 2.148(1),
Pd(1)–Cl(1) 2.3451(5), Pd(1)–Cl(2) 2.2946(4), C(11)–Pd(1)–N(3) 86.60(6),
C(11)–Pd(1)–Cl(2) 91.53(5), Cl(1)–Pd(1)–Cl(2) 87.18(2), Cl(1)–Pd(1)–N(3)
94.60(4).
Morph), 51.8 (NCH2 Morph), 50.9 (NCH2), 50.1 (NCH2), 20.6 (p-CH3
Mes), 17.3 (m-CH3 Mes). Anal. calcd. (%) for C22H28BF4N3O: C 60.43,
H 6.45, N 9.61; found: C 60.21, H 6.42, N 9.56.
1-Dipp-3-{2-(4-morpholinyl)phenyl}imidazolidin-2-ylidene (7)
Within a dinitrogen-filled glovebox, compound 5 (400 mg,
0.834 mmol) was combined with 1 equiv. of NaHMDS (153 mg,
0.834 mmol) in a 4 dram vial. To the vial was added 5 mL of THF
and the mixture was stirred for 1 h. Filtration through a plug of
celite gave a clear solution, which was concentrated to approxi-
mately 1 mL. To this material was added 5 mL of hexanes and the
resultant mixture was cooled to −35 °C for 18 h, resulting in crys-
tallization of 7. The supernatant was decanted and the crystals
were washed with cold hexanes (3 × 3 mL) and dried in vacuo,
giving 245 mg of the product. A second crop of 43 mg was obtained
from the combined supernatant and washings after cooling to −35
°C for an additional 48 h, giving a total yield of 88% (288 mg, 0.736
mmol). 1H NMR (500 MHz, C6D6) ␦: 7.80 (dd, J = 7.8, 1.6 Hz, 1H, 6-Ph),
7.26 (dd, J = 8.3, 7.1 Hz, 1H, p-Dipp), 7.17 (d, J = 8.1 Hz, 2H, m-Dipp),
7.09 (ddd, J = 8.0, 7.4, 1.7 Hz, 1H, 4-Ph), 6.97 (td, J = 7.6, 1.4 Hz, 1H,
5-Ph), 6.79 (dd, J = 8.0, 1.4 Hz, 1H, 3-Ph), 3.94 (dd, J = 11.0, 9.0 Hz, 2H,
NCH2), 3.68 (t, J = 4.6 Hz, 4H, OCH2 Morph), 3.47 (dd, J = 11.0, 9.0 Hz,
2H, NCH2), 3.17 (sp, J = 6.9 Hz, 2H, CH(CH3)2), 2.85 (t, J = 4.6 Hz, 4H,
NCH2 Morph), 1.29 (d, J = 6.9 Hz, 6H), 1.23 (d, J = 6.9 Hz, 6H). 13C{1H}
NMR (126 MHz, C6D6) ␦: 243.68 (carbene), 147.2, 147.0, 139.5, 138.6,
129.8 (6-Ph), 128.4 (p-Dipp), 127.1 (4-Ph), 124.1 (m-Dipp), 123.8 (5-Ph),
118.9 (3-Ph), 67.4 (NCH2 Morph), 54.6 (NCH2), 51.6 (OCH2 Morph),
48.6 (NCH2), 29.0 (CH(CH3)2), 25.2 (CH(CH3)2), 23.7 (CH(CH3)2). Anal.
calcd. (%) for C25H33N3O: C 76.69, H 8.49, N 10.73; found: C 76.51,
H 8.30, N 10.61.
Table 3. GC yields for the arylation of various amines with chloroben-
zene employing 9–14 as catalysts.
Morpholine
yield (%)
Aniline
yield (%)
Octylamine
yield (%)
1-Mesityl-3-{2-(4-morpholinyl)phenyl}imidazolidin-2-ylidene (8)
This was prepared similarly to 7 from compound 6 (400 mg,
0.915 mmol), giving a crystalline white solid in 85% yield (272 mg,
0.778 mmol). 1H NMR (500 MHz, C6D6) ␦: 7.87 (dt, J = 7.8, 1.2 Hz, 1H,
6-Ph), 7.09 (ddd, J = 8.0, 7.4, 1.7 Hz, 1H, 4-Ph), 6.98 (td, J = 7.6, 1.4 Hz,
1H, 5-Ph), 6.84 (s, 2H, m-Mes), 6.81 (dd, J = 8.0, 1.4 Hz, 1H, 3-Ph), 3.92
(m, 2H, NCH2), 3.64 (m, 4H, OCH2 Morph), 3.34 (m, 2H, NCH2), 2.84
(t, J = 4.6 Hz, 4H, NCH2 Morph), 2.25 (s, 6H, o-CH3 Mes), 2.17 (s, 3H,
p-CH3 Mes). 13C{1H} NMR (126 MHz, C6D6) ␦: 243.9 (carbene), 146.8,
139.7, 138.7, 136.5, 136.0, 129.6 (6-Ph), 129.5 (m-Mes), 126.9 (4-Ph),
123.8 (5-Ph), 118.9 (3-Ph), 67.4 (OCH2 Morph), 51.7 (NCH2), 51.6 (NCH2
Morph), 48.5 (NCH2), 21.1 (p-CH3 Mes), 18.2 (m-CH3 Mes). Anal.
calcd. (%) for C22H27N3O: C 75.61, H 7.79, N 12.02; found: C 75.92,
H 8.22, N 12.01.
Entry
Catalyst
1
9
10
11
12
13
18
11
13
14
4
8
20
6
8
2
3
4
5
6
7
8
9
10
11
1
8
95
86
42
35
>99
34
>99
>99
10
9
>99
15
>99
>99
28
14
9a
10a
13a
14a
25
66b
>99
Note: Conditions: 2 mol% Pd, PhCl/amine/NaOtBu = 1:1.2:1.4, [ArCl] = 0.5 mol
L−1, toluene. Reactions were performed on a 0.25 mmol scale with reaction times
of 18–24 h (unoptimized). Yields were determined from GC data calibrated using
authentic samples with dodecane as the internal standard.
a1.2 equiv. of KOtBu, DME solvent.
bComplete consumption of starting material was observed. The low yield is
attributed to formation of diarylation product.
Pd(1-Dipp-3-{2-(4-morpholinyl)phenyl}imidazolidin-2-ylidene)
(cinnamyl)Cl (9)
Within a dinitrogen-filled glovebox, a slight excess of carbene 7
(300 mg, 0.766 mmol) in 2 mL of THF was added dropwise to a
rapidly stirring suspension of [Pd(cinnamyl)Cl]2 (191 mg, 0.369
mmol) in 2 mL of THF in a 4 dram vial, resulting in a pale yellow
solution. The reaction mixture was stirred for 30 min and then
removed from the glovebox and worked up under ambient atmo-
sphere. The reaction mixture was filtered through a short plug of
silica, which was washed down with THF (5 mL). Evaporation of
the solvent afforded the product as a light yellow powder
[1-Mesityl–3-{2-(4-morpholinyl)phenyl}imidazolidin–2-ylium][BF4] (6)
This was prepared similarly to 4 from diamine 2 (819 mg, 2.41
mmol) and 1.4 equiv. of NH4BF4 (354 mg, 3.38 mg), giving the
product as an analytically pure white powder in 88% yield (932 mg,
1
2.13 mmol). H NMR (500 MHz, CDCl3) ␦: 8.56 (s, 1H, NCHN), 7.53
(dd, J = 7.9, 1.3 Hz, 1H, 6-Ph), 7.40 (t, J = 7.8 Hz, 1H, 4-Ph), 7.31–7.27
(ov m, 2H, 3,5-Ph), 7.01 (s, 2H, m-Mes), 4.86 (dd, J = 11.9, 9.7 Hz,
2H, NCH2), 4.45 (dd, J = 12.0, 9.6 Hz, 2H, NCH2), 3.80 (t, J = 4.6 Hz, 4H,
OCH2 Morph), 2.98 (t, J = 4.6 Hz, 4H, NCH2 Morph), 2.38 (s, 6H,
o-CH3 Mes), 2.33 (s, 3H, p-CH3 Mes). 1H NMR (500 MHz, DMSO-d6) ␦:
9.22 (s, 1H, NCHN), 7.60 (dd, J = 7.9, 1.4 Hz, 1H, 6-Ph), 7.49 (ddd, J =
8.0, 7.4, 1.4 Hz, 1H, 4-Ph), 7.41 (dd, J = 8.1, 1.3 Hz, 1H, 3-Ph), 7.30 (td,
J = 7.6, 1.1 Hz, 1H, 5-Ph), 7.11 (s, 2H, m-Mes), 4.72 (dd, J = 12.0, 9.3 Hz,
2H, NCH2), 4.41 (dd, J = 11.9, 9.5 Hz, 2H, NCH2), 3.78 (t, J = 4.5 Hz, 4H,
OCH2 Morph), 2.94 (t, J = 4.5 Hz, 4H, NCH2 Morph), 2.35 (s, 6H, o-CH3
Mes), 2.30 (s, 3H, p-CH3 Mes). 13C{1H} NMR (126 MHz, DMSO-d6)
␦: 159.3 (NCHN), 146.8, 139.7, 135.3, 131.1, 130.6 (4-Ph), 130.1,
129.5 (m-Ph), 126.0 (6-Ph), 124.8 (5-Ph), 122.0 (3-Ph), 66.3 (OCH2
1
in >99% yield (479 mg, 0.736 mmol). H NMR (500 MHz, C6D6) ␦:
8.78 (br s, 1H, 6-Ph), 7.20–7.18 (ov m, 2H), 7.14 (d, J = 7.8 Hz, 1H),
7.09–6.98 (m, 7H), 6.69 (dd, J = 7.9, 1.3 Hz, 1H, 3-Ph), 5.04 (dt, J = 12.4,
9.3 Hz, 1H, cinnamyl CH), 4.37 (br d, J = 12.8 Hz, 1H, cinnamyl CH),
3.72 (t, J = 4.5 Hz, 4H, OCH2 Morph), 3.7–3.3 (br ov m, 6H, NCH2
Morph + CH(CH3)2), 3.02 (br s, 2H, NCH2), 2.91 (br s, 1H, cinnmyl
CH2), 2.81 (br s, 2H, NCH2), 1.75 (br d, J = 8.5 Hz, 1H, cinnamyl CH2),
1.44 (br s, 6H, CH(CH3)2), 1.09 (d, J = 6.8 Hz, 6H, CH(CH3)2). 13C{1H}
NMR (126 MHz, C6D6) ␦: 211.9 (carbene), 146.9, 138.5, 136.4, 135.5,
131.7 (6-Ph), 129.6, 128.8, 128.4, 128.0, 126.8, 124.7, 123.5, 119.1 (3-Ph),
109.1 (cinnamyl CH), 90.6 (cinnamyl CH), 67.5 (OCH2 Morph), 55.0
Published by NRC Research Press