Supporting information
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Strassberger et al.
Supporting information for the communication:
A facile route to ruthenium-carbene complexes and their
application in furfural hydrogenation
Z. Strassbergera, M. Mooijmanb, E. Ruijterb, A. H. Albertsa, C. de Graafb, R. V. A. Orrub* and
G. Rothenberga*
Van ‘t Hoff Institute of Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht
166, 1018 WV Amsterdam, The Netherlands
Tel. +31 (0)20 525 6963, Fax. +31 (0)20 525 5604, e-mail: g.rothenberg@uva.nl
a
b
Department of Chemistry & Pharmaceutical Sciences, Vrije Universiteit Amsterdam, De
Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
Materials and Instrumentation. All reactions were carried out under atmospheric
conditions, unless stated otherwise. Infrared (IR) spectra were obtained from neat samples and
wavelengths (ν) are reported in cm-1. 1H and 13C nuclear magnetic resonance (NMR) spectra
were recorded at 200.13, 250.13 or 400.13 and 62.90, 100.62 or 125.70 MHz respectively
with chemical shifts (δ) reported in reported in ppm, internally referenced to residual solvent
resonances for CDCl3 (1H δ: = 7.26 ppm;
13
C{1H} δ: = 77.00 ppm), and coupling constants
(J) are reported in Hz. Electrospray Ionisation (ESI) mass spectrometry was carried out with a
micrOTOF-Q instrument in positive ion mode. Chromatographic purification refers to flash
chromatography using the indicated solvent (mixture) and Baker 7024-02 silica gel (40 μ, 60
Å). Thin layer chromatography was performed using silica plates from Merck (Kieselgel 60
F254 on aluminium with fluorescence indicator. Compounds on TLC were visualised by UV
detection unless stated otherwise. DCM was dried and freshly distilled from CaH2 prior to
use. Other commercially available reagents were used as purchased.
General procedure for synthesising the 2H-2-imidazoline archetypes.
All reactions were performed using a concentration of 1 M of aldehyde, 1 M of amine, and
0.5 M of isocyanide in dry CH2Cl2 or MeOH. Na2SO4 and the aldehyde were added, at 25 ºC,
to a stirred solution of the amine. The mixture was stirred for 2 h. The isocyanide was then
added and the mixture was stirred at 25 ºC for an additional 18 h, filtered and concentrated in
vacuo. The crude product was purified by flash column chromatography (cyclohexane–
EtOAc–Et3N = 2:1:0.01, gradient, unless stated otherwise).
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Supporting information
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Strassberger et al.
2H-2-Imidazoline B: According to the procedure for synthesis of
2-imidazolines, the reaction between benzylamine (428.6 mg, 436.5 μl,
4.00 mmol), isobutyraldehyde (288.4 mg, 365.1 μl, 4.00 mmol) and
9-isocyano-9H-fluorene (382.5 mg, 2.00 mmol) afforded 2H-2imidazoline B (530.2 mg, 1.50 mmol, 75 %) as a dark orange foam. 1H
NMR (250 MHz CDCl3) δ: 7.62 (t, J = 15, 2H), 7.50-7.45 (m, 2H), 7.41-7.28 (m, 8H), 7.01
(m, 1H), 7.01 (d, J = 7.2, 1H), 4.66 (d, J = 15.0, 1H), 4.31 (d, J = 15.0, 1H), 3.51 (d, J = 8.2,
1H), 2.04-1.94 (m, 1H), 0.88 (d, J = 6.8, 3H), 0.23 (d, J = 6.8, 3H);
13
C NMR (125 MHz
CDCl3) δ: 160.52 (CH), 150.93 (C), 145.84 (C), 140.65 (C), 140.33 (C), 136.16 (C), 128.88
(CH), 128.63 (CH), 128.53 (CH), 128.27 (CH), 128.19 (CH), 127.95 (CH), 127.86 (CH),
127.71 (CH), 126.97 (CH), 126.41 (CH), 124.36 (CH), 119.81 (CH), 119.61 (CH), 83.76
(CH), 72.73 (CH3), 52.82 (CH2), 29.96 (CH), 20.96 (CH3), 19.80 (CH3); IR: 3057.76,
3039.43, 2972.89, 2923.70, 2875.48, 1591.81, 1495.36, 1476.56, 1448.11, 1351.66, 1299.58,
1207.96, 1144.31, 1077.76, 1028.09, 1012.18, 945.15, 783.61, 749.37, 731.05, 717.06,
715.61, 696.81, 649.55, 619.65; HRMS calculated for C25H25N2 (M++H) 353.2012, found
353.1998.
2H-2-Imidazoline C: Experimental details and analytical data for this
compound were reported elsewhere.1
2H-2-Imidazoline D: According to the procedure for synthesis of
2-imidazolines, the reaction between tert-butylamine (1.46 g, 20.0 mmol),
p-formaldehyde (600 mg, 20.0 mmol), and 9-isocyano-9H-fluorene (2.0 g,
10.5 mmol), followed by flash column chromatography, afforded 2H-2imidazoline D (2.58 g, 17.8 mmol, 89%) as a light yellow solid. Crystallization from
pentane/Et2O afforded white crystals. Mp: 95-96 °C. 1H NMR (250 MHz, CDCl3): δ (ppm)
7.68 (d, J=6.9 Hz, 2H), 7.50-7.32 (m, 7H), 3.73 (s, 2H), 1.42 (s, 9H).
13
C NMR (63 MHz,
CDCl3): δ (ppm) 155.6 (CH), 150.6 (2xC), 140.3 (2xC), 128.7 (2x CH), 128.4(2x CH), 124.2
(2x CH), 120.1 (2x CH), 79.1 (C), 55.6 (CH2), 53.1 (C), 28.9 (3x CH3). IR (neat): 2973 (s),
1674 (m), 1585 (s), 1450 (s), 1236 (s). HRMS (EI, 70 eV): calcd for C19H20N2 (M+) 276.1626,
found 276.1617. Anal. Calcd for C19H20N2 (%): C 82.57, H 7.29, N 10.14. Found: C 82.42, H
7.44, N 10.06.
1
R. S. Bon, C. Hong, M. J. Bouma, R. F. Schmitz, F. J. J. de Kanter, M. Lutz, A.L. Spek, R. V. A. Orru Org.
Lett. 2003, 5, 3759-3762
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Procedure II for the synthesis of 2-imidazolinium salts.
Reactions were carried out at a concentration of 1 M of imidazoline in acetone. The halide
(1eq) was added to a stirred solution of the imidazoline and NaI (1 eq.). The reaction mixture
was stirred at rt for 18 h. Then, the reaction mixture was filtrated over Celite and concentrated
in vacuo.
Imidazolinium iodide 1: According to general procedure II for the
synthesis of 2-imidazolinium salts, the reaction between 2-imidazoline D
(276.2
mg,
1.00
mmol),
NaI
(149.9
mg,
1.00
mmol)
and
1-(chloromethoxy)-2-methoxyethane (123.0 mg, 112.8 μl, 1.00 mmol)
afforded 2-imidazolinium iodide 1 (482.1 mg; 0.979 mmol; 98%) as a
yellow foam. 1H NMR (500 MHz, CDCl3) δ 9.794 (s, 1H), 7.74 (d, J = 7.2, 2H), 7.69 (d, J =
7.2, 2H), 7.52 – 7.48 (m, 2H), 7.44 – 7.40 (m, 2H), 4.832 (s, 2H), 4.291 9s, 2H), 3.44 (t, J =
1.5, 2H), 3.207 (s, 3H), 3.16 (t, J = 1.5, 2H), 1.02 (s, 9H);
13
C NMR (125 MHz, CDCl3) δ:
156.98 (CH), 142.35 (C), 140.12 (C), 130.99 (CH), 129.24 (CH), 124.59 (CH), 120.77 (CH),
76.28 (CH2), 73.48 (C), 71.12 (CH2), 68.70 (CH2), 58.90 (CH3), 58.57 (C), 57.81 (CH2),
28.02 (CH3); IR: 2982.53 (m), 2916.95 (m), 2876.92 (m), 1624.12 (s), 1448.11 (m), 1295.24
(br), 1229.18 (m), 1181.92 (m), 1095.60 (m), 1032.06 (br), 844.85 (m), 767.69 (s), 756.12 (s),
734.42 (s); HRMS calculated for C23H29N2O2 (M+-I-) 365.2197, found 365.2210.
Imidazolinium iodide 2: According to general procedure II for the
synthesis
of
2-imidazolinium
salts,
the
reaction
between
2-imidazoline D (107.40 mg, 0.388 mmol), NaI (58.30 mg, 0.338
mmol) and 2-(chloromethyl)-1,3,5-triisopropylbenzene (98.3 mg, 31.1
μl, 0.338 mmol) afforded 2-imidazolinium iodide 2 (251.7 mg, 0.386
mmol, 99.5%) as a yellow foam. 1H NMR (500 MHz, CDCl3) δ 8.656 (s, 1H), 7.82 (d, J =
6.2, 2H), 7.70 (d, J = 6.2, 2H), 7.48 (t, J = 6.0, 2H), 7.37 (t, J = 6.0, 2H), 6.823 (s, 2H), 4.377
(s, 2H), 4.306 (s, 2H), 2.82 – 2.75 (m, 1H), 2.70 – 2.28 (m, 2H), 1.633 (s, 9H), 1.19 (d, J =
5.6, 6H), 1.04 (d, J = 5.2, 12H);
13
C NMR (125 MHz, CDCl3) δ: 154.70 (CH), 150.20 (C),
148.15 (C), 141.69 (C), 139.96 (C), 130.88 (CH), 129.24 (CH), 124.83 (CH), 123.29 (C),
121.49 (CH), 120.63 (CH), 75.08 (C), 58.18 (CH2), 41.59 (CH2), 29.21 (CH), 28.28 (2x CH),
24.32 (3x CH3), 23.84 (2x CH3), 23.77 (4x CH3); 2988.76 (m), 2865.54 (m), 2854.97 (m),
1633.65 (m), 1610.30 (m), 1375.96 (m) 1345.25 (m), 1205.65 (m), 1100.86 (m), 1033.06 (m),
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865.88 (m), 785.98 (m), 746.12 (m); HRMS calculated for C35H45N2 (M+-I-) 493.3577, found
493.3562.
Imidazolinium iodide 3: According to general procedure II for the
synthesis of 2-imidazolinium salts, the reaction between 2-imidazoline
D (107.40 mg, 0.388 mmol), NaI (58.30 mg, 0.338 mmol) and 2(chloromethyl)-1,3,5-trimethylbenzene (25.5 mg; 0.388 mmol) afforded
2-imidazolinium iodide 3 (170.6 mg, 0.318 mmol, 81.9%) as a yellow foam. 1H NMR (500
MHz, CDCl3) δ 9.121 (s, 1H), 7.65 (d, J = 7.6, 2H), 7.30 (d, J = 7.6, 2H), 7.34 – 2.25 (m, 4H),
6.516 (s, 2H), 4.459 (s, 2H), 3.668 (s, 2H), 2.090 (s, 3H), 1.0907 (s, 6H), 1.601 (s, 9H);
13
C
NMR (125 MHz, CDCl3) δ: 155.44 (CH), 141.57 (C), 139.50 (C), 138.25 (C), 137.31 (C),
130.54 (CH), 129.13 (CH), 128.86 (CH), 125.28 (C), 124.18 (CH), 120.30 (CH), 74.40 (C),
57.89 (CH2), 52.57 (CH2), 27.96 (3x CH3), 20.52 (CH3), 19.65 (2x CH3); IR: 2973.37 (br),
2865.35 (br), 1653.53, 1623.63 (s), 1576.38 (m), 1448.11(s), 1375.29 (m), 1369.02 (m),
1239.31 (m), 1213.27 (m), 1185.30 (m), 1042.56 (br), 910.91 (m), 850.64 (m), 758.05 (s),
730.08 (s); HRMS calculated for C29H33N2 (M+-I-) 409.2638, found 409.2627.
Imidazolinium iodide 4: According to general procedure II for
the synthesis of 2-imidazolinium salts, the reaction between
2-imidazoline A (221.2 mg, 0.508 mmol), NaI (76.44 mg, 0.51
mmol) and p-nitrobenzyl bromide (110.2 mg, 0.51 mmol)
afforded 2-imidazolinium iodide 4 (293.0 mg, 0.400 mmol, 78.4
%) as a yellow foam as a yellow foam as a 73:23 mixture of diastereoisomers A and B. 1H
NMR (500 MHz, CDCl3) δ 10.545 (s, 1H, isomer A), 10.499 (s, 1H, isomer B), 8.19 (d, J =
9.0, 2H, isomer A), 8.05 (d, J = 8.5, 2H, isomer B), 7.69 – 7.20 (m 4H, isomers A and B),
7.38 (d, J = 7.0, 2H, isomer B), 7.24 – 7.18 (m, 4H, isomers A and B), 7.10 - 7.08 (m, 4H),
6.87 (d, J = 8.5, 2H, isomer B), 6.82 (d, J = 8.5, 2H, isomer A), 5.824 (s, 1H, isomer A), 5.65
(d, J = 15.7, 1H, isomer A), 5.49 (d, J = 14.2, 1H, isomer B), 5.36 (d, J = 14.5, 1H, isomer A),
5.200 (s, 1H, isomer B), 4.87 (d, J = 15.7, 1H, isomer A), 4.78 (d, J = 14.5, 1H, isomer B),
4.72 (d, J = 14.5, 1H, isomer B), 4.22 (d, J = 14.5, 1H, isomer A), 4.05 (d, J = 14.2, 1H,
isomer B), 3.793 (s, 3H, isomer B), 3.786 (s, 3H, isomer A), 3.592 (s, 3H, isomer A), 3.234
(s, 3H, isomer B);
13
C NMR (125 MHz, CDCl3) δ: 167.93 (C, isomer A), 166.09 (C, isomer
B), 159.93 (C, isomer B), 159.68 (C, isomer A), 157.28 (CH, isomer A), 156.53 (CH, isomer
A), 147.21 (C, isomer B), 147.15 (C, isomer A), 141.11 (C, isomer A), 139.93 (C, isomer B),
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136.14 (C, isomer B), 135.95 (C, isomer B), 134.82 (C, isomer B), 134.78 (C, isomer B),
130.93 (CH), 130.46 (CH), 130.23 (CH), 129.76 (C, isomer A), 129.70 (C, isomer B), 129.26
(CH), 129.23 (CH), 128.86 (CH), 128.59 (CH), 128.40 (CH), 128.31 (CH), 128.15 (C),
127.92 (CH), 127.58 (CH), 127.33 (CH), 127.13 (CH), 126.63 (CH), 123.73 (CH, isomer A),
123.41 (CH, isomer B), 122.60 (C, isomer A), 122.31 (C, isomer B), 114.07 (CH, isomer B),
113.94 (CH, isomer A), 80.96 (C, isomer B), 80.56 (C, isomer A), 73.06 (CH, isomer B),
69.84 (CH, isomer A), 54.95 (CH3, isomer B), 54.87 (CH3, isomer A), 53.69 (CH3, isomer A),
52.49 (CH3, isomer B), 50.29 (CH2, isomer A), 50.26 (2x CH2, isomer A/B), 49.22 (CH2,
isomer B); IR: 3046.67 (m), 3019.18 (m), 2956.97 (m), 2927.08 (m), 1743.71 (m), 1630.39
(m), 1339.12 (s), 1246.54 (s), 1082.10 (s), 1012.66 (m), 835.21 (m), 694.88 (m); HRMS
calculated for C32H29ClN3O5 (M+-I-) 570.1790, found 570.1763.
Imidazolinium iodide 5: According to general procedure II for
the synthesis of 2-imidazolinium salts, the reaction between 2imidazoline A (221.2 mg, 0.508 mmol), NaI (76.44 mg, 0.51
mmol) and (S)-methyl 3-bromo-2-methylpropanoate (92.33 mg,
64.92 μl, 0.51 mmol) afforded 2-imidazolinium iodide 5 (186.1
mg, 0.267 mmol, 52 %) as a yellow foam as a 51:49 mixture of diastereoisomers. 1H NMR
(500 MHz, CDCl3) δ 9.118 (s, 1H), 9.059 (s, 1H), 7.45 – 7.44 (m, 2H), 7.39 – 7.37 (m, 2H),
7.28 – 7.23 (m, 4H), 7.07 – 6.66 (m, 8H), 6.93 – 6.88 (m, 4H), 6.82 – 6.80 (m, 4H), 6.72 -6.69
(m, 2H), 5.469 (s, 1H), 4.99 (d, J = 19.0, 1H), 4.88 (d, J = 14.5, 1H), 4.890 (s, 1H), 3.753 (s,
3H), 3.702 (s, 3H), 3.677 (s, 3H), 3.97 – 3.91 (m, 4H), 3.37 – 3.30 (m, 1H), 3.25 – 3.20 (m,
1H), 3.34 (s, 3H), 3.08 (s, 3H) ;
13
C NMR (125 MHz, CDCl3) δ: 171.28 (C), 168.40 (C),
159.48 (C), 159.38 (C), 157.40 (CH), 156.82 (CH), 139.65 (C), 139.61 (C), 135.23 (C),
134.30 (C), 134.08 (C), 131.98 (C), 130.81 (C), 129.98 (CH), 129.52 (CH), 129.05 (CH),
128.51 (CH), 128.40 (CH), 128.17 (CH), 127.96 (CH), 127.90 (CH), 125.99 (CH), 125.69
(CH), 125.25 (C), 125.02 (C), 124.92 (C), 114.10 (CH), 114.01 (CH), 80.66 (C), 79.74 (C),
72.74 (CH), 69.19 (CH), 55.03 (CH3), 55.01 (CH3), 54.94 (CH3), 53.09 (CH3), 52.22 (CH3),
51.84 (CH3), 49.28 (CH2), 48.92 (CH2), 41.86 (CH), 41.75 (CH), 18.07 (CH3), 16.00 (CH3);
IR 3038.95 (m), 2954.08 (m), 2846.54 (m), 1624.12 (m), 1635.69 (m), 1512.72 (m), 1487.65
(m), 1433.64 (m), 1234.48 (m), 1156.85 (m), 1149.13 (m), 1034.72 (m), 825.56 (m), 756.56
(m); HRMS calculated for C30H32ClN2O5 (M+-I-) 535.1994, found 535.1949.
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Imidazolinium iodide 6: According to general procedure II for
the synthesis of 2-imidazolinium salts, the reaction between
2-imidazoline A (221.2 mg, 0.508 mmol), NaI (76.44 mg, 0.51
mmol) and methoxymethyl chloride (41.06 mg, 38.7 μl, 0.51
mmol) afforded 2-imidazolinium iodide 6 (274.1 mg, 0.427
mmol, 84 %) as a yellow foam as a 63:37 mixture of diastereoisomers (A and B). 1H NMR
(500 MHz, CDCl3) δ 10.827 (s, 1H, isomer B), 10.438 (s, 1H, isomer A), 7.46 – 7.40 (m, 1H,
isomer A), 7.38 – 7.40 (m, 4H), 7.17 – 7.13 (m, 9H), 7.09 – 7.04 (m, 3H), 6.92 – 6.90 (m,
4H), 6.87 – 6.83 (m, 5H), 5.900 (s, 1H, isomer A), 5.61 (d, J = 14.0, 1H, isomer B), 5.38 (d, J
= 9.7, 1H, isomer A), 5.25 (d, J = 14.5, 1H, isomer A), 5.08 (d, J = 9.7, 1H, isomer A), 5. 05
(d, J = 10.7, 1H, isomer B), 5.01 (d, J = 10.7, 1H, isomer B), 4.21 (d, J = 14.5, 1H, isomer A),
4.19 (d, J = 14.0, 1H, isomer A), 3.871 (s, 3H, isomer A), 3.814 (s, 3H, isomer B), 3.799 (s,
6H, isomer A/B), 3.496 (s, 6H, isomer A/B), 3.267 (s, 2H, isomer A), 3.170 (s, 2H, isomer B);
C NMR (125 MHz, CDCl3) δ: 168.11 (C, isomer A), 165.92 (C, isomer B), 159.90 (C,
13
isomer B), 159.71 (C, isomer A), 153.74 (CH, isomer A), 152.70 (CH, isomer B), 136.06 (C),
135.02 (C), 134.86 (C), 130.42 (CH), 130.35 (CH), 130.14 (C), 129.94 (CH), 129.17 (C),
129.04 (CH), 128.97 (CH), 128.84 (CH), 128.35 (CH), 128.19 (CH), 127.93 (C), 125.70
(CH), 126.48 (CH), 122.52 (C), 122.42 (C), 114.13 (CH, isomer B), 114.01 (CH, isomer B),
79.30 (C), 78.80 (C), 78.65 (C), 78.41 (C), 73.32 (CH, isomer B), 70.69 (CH, isomer A),
57.43 (CH3), 57.31 (CH3), 54.95 (CH3), 54.85 (CH3), 54.29 (CH3), 52.17 (CH3), 50.34 (CH2,
isomer A), 50.19 (CH2, isomer B); IR: 2979.64 (m), 2939.61 (m), 2827.26 (m), 1740.33 (s),
1627.97 (m), 1609.65 (s), 1512.72 (s), 1448.11 (s), 1245.09 (m), 1178.06 (s), 1083.07 (m),
1025.68 (m), 819.29 (m), 698.25 (m); HRMS calculated for C23H27N2O2 (M+-I-) 363.2067,
found 363.2053.
Imidazolinium iodide 7: According to general procedure II for the
synthesis 2-imidazolinium salts, the reaction between 2-imidazoline
C (100.0 mg, 0.261 mmol), NaI (40.0 mg, 0.268 mmol) and
n-butylbromide
(35.8
mg,
28.2
μl,
0.261
mmol)
afforded
2-imidazolinium iodide 7 (130.0 mg, 0.224 mmol, 86 %) as a yellow
foam. 1H NMR 500 MHz [CDCl3] (δ): 9.773 (s, 1H), 7.67 (d, J = 7.55, 1H), 7.62 (d, J = 7.55,
1H), 7.58 – 7.49 (m, 4H), 7.46 (t, J = 7.55, 1H), 7.41 (t, J = 7.48, 1H), 7.32 – 7.23 (m, 2H),
6.95 (d, J = 6.95, 2H), 5.24 (d, J = 14.35, 1H), 4.73 (d, J = 14.35, 1H), 4.33 (d, J = 5.85, 1H),
3.787 (s, 3H), 2.88 – 2.77 (m, 1H), 2.75 – 2.63 (m, 1H), 2.17 – 2.05 (m, 2H), 1.40 – 1.22 (m,
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2H), 1.08 – 0.91 (m, 2H), 0.63 (d, J = 6.85, 3H), 0.58 (t, J = 7.35, 3H), 0.54 (d, J = 6.95, 3H);
13
C NMR 125 MHz [CDCl3] (δ): 159.88 (C), 159.40 (CH), 142.93 (C), 141.01 (C), 140.14
(C), 138.06 (C), 130.99 (CH), 130.77 (CH), 130.67 (CH), 129.65 (CH), 128.98 (CH), 127.83
(CH), 126.79 (CH), 125.15 (CH), 124.45 (C), 120.79 (CH), 120.44 (CH), 114.56 (CH), 78.93
(CH), 74.21 (CH), 55.22 (CH3), 51.24 (CH2), 44.61 (CH2), 30.24 (CH2), 27.47 (CH), 19.20
(CH2), 19.00 (CH3), 18.43 (CH3), 12.96 (CH3); IR: 3029.31, 3007.61, 2965.17, 2907.79,
1712.36, 1609.65, 1606.76, 1583.61, 1512.72, 1448.11, 1354.56, 1248.47, 1244.13, 1179.03,
1028.58, 848.22, 818.33, 773.96, 762.87, 742.14; HRMS calculated for C30H35N2O (M+-I-)
439.2744, found 439.2722.
Imidazolinium iodide 8: According to general procedure II for the
synthesis of 2-imidazolinium salts, the reaction between 2-imidazoline
B (60.0 mg, 0.170 mmol), NaI (40.0 mg, 0.261 mmol) and (S)-methyl
3-bromo-2-methylpropanoate (47.2 mg, 33.2 μl, 0.261 mmol) afforded
2-imidazolinium iodide 8 (150.0 mg, 0.258 mmol, 99%) as a 5:2
mixture of diastereoisomers as a dark yellow foam. 1H NMR 500 MHz [CDCl3] (δ): 9.277 (s,
1H), 7.41 – 7.58 (m, 4H), 7.31 – 7.30 (m, 2H), 7.28 – 7.19 (m, 5H), 7.16 – 7.11 (m, 2H), 7.04
– 7.02 (m, 1H), 7.01 – 6.89 (m, 1H), 5.19 (d, J = 14.7, 1H), 5.52 (d, J = 14.7, 1H), 4.07 – 4.06
(m, 1H), 3.488 (s, 3H), 3.50 – 3.03 (m, 1H), 3.38 – 3.32 (m, 1H), 3.26 – 3.22 (m, 1H), 3.16 –
3.11 (m, 1H), 3.05 – 3.01 (m, 1H), 2.70 – 2.66 (m, 1H), 2.59 – 2.55 (m, 1H), 2.05 – 1.86 (m,
1H), 1.924 (s, 3H), 1.09 – 1.02 (m, 4H), 0.46 (d, J = 1.8, 3H), 0.38 (d, J = 1.8, 3H); 13C NMR
125 MHz [CDCl3] (δ): 173.56 (C), 159.42 (CH), 145.45 (C), 139.86 (C), 132.47 (C), 130.67
(CH), 130.40 (CH), 130.07 (CH), 128.84 (CH), 128.52 (CH), 127.61 (CH), 127.16 (CH),
126.87 (CH), 124.44 (CH), 120.35 (CH), 120.10 (CH), 74.61 (C), 74.47 (CH), 51.86 (CH),
51.78 (CH2), 33.89 (CH2), 27.48 (CH), 18.93 (CH3), 18.14 (CH3), 17.90 (CH3); IR: 2915.98,
2819.06, 1690.18, 1619.78, 1450.52, 1383.49, 1278.37, 1204.59, 1155.40, 762.39, 753.71,
732.01, 708.38, 644.25, 624.47, 555.52; HRMS calculated for C30H33N2O2 (M+-I-) 453.37,
found 453.218.
Imidazolinium iodide 9: According to general procedure II for the
synthesis of 2-imidazolinium salts, the reaction between 2-imidazoline
B (59.9 mg, 0.170 mmol), NaI (40 mg, 0.261 mmol) and benzyl bromide
(44.6 mg, 31.0 μl, 0.261 mmol) afforded 2-imidazolinium iodide 9 (82.5
S7
Supporting information
S8
Strassberger et al.
mg, 0.144 mmol, 85.0 %) as a dark yelow foam. 1H NMR 500 MHz [CDCl3] (δ): 9.663 (s,
1H), 7.72 (d, J = 7.5, 1H), 7.66 (d, J = 7.5, 1H), 7.57 (d, J = 7.5, 2H), 7.54 – 7.51 (m, 3H),
7.49 – 7.45 (m, 4 H), 7.45 – 7.39 (m, 1H), 7.37 – 7.24 (m, 2H), 7.17 – 7.15 (m, 1H), 7.14 –
7.10 (m, 2H), 6.96 – 6.9 (m, 2H), 5.22 (d, J = 14.7, 1H), 4.92 (d, J = 7.5, 1H), 4.46 (m, 1H),
4.40 (d, J = 14.5, 1H), 4.06 (d, J = 14.7, 1H), 2.31 – 2.11 (m, 1H), 0.59 (d, J = 7.0, 3H), 0.46
(d, J = 7.0, 3H);
13
C NMR 125 MHz [CDCl3] (δ): 160.02 (CH), 142.74 (C), 141.48 (C),
140.42 (C), 138.10 (C), 132.89 (C), 132.62 (C), 131.17 (CH), 130.87 (CH), 129.48 (CH),
129.28 (CH), 129.25 (2x CH), 129.14 (CH), 128.83 (CH), 128.79 (2x CH), 128.77 (CH),
128.71 (CH), 128.04 (CH), 127.89 (CH), 127.40 (CH), 126.07 (CH), 120.86 (CH), 120.44
(CH), 79.20 (C), 75.49 (CH), 52.41 (CH2), 49.06 (CH2), 27.78 (CH), 19.28 (CH3), 18.80
(CH3); IR: 3077.53, 3045.22, 2985, 42, 2929.97, 1700.31, 1620.74, 1451.48, 1363.24,
1221.95, 1084.51, 1030.50, 755.16, 695.84; HRMS calculated for C32H31N2 (M+-I-) 443.2482,
found 443.2462.
The data for imidazolinium iodide 10 have been published elsewhere.2
2
R. S. Bon, F. J. J. de Kanter, M. Lutz, A. L. Spek, M. C. Jahnke, F. E. Hahn, M. B. Groen, R V. A. Orru
Organometallics 2007, 26, 3639-3650.
S8
Supporting information
S9
Strassberger et al.
Procedures for performing control NMR experiments.
NMR control experiment 1: In a flame-dried NMR tube and under inert atmosphere KOtBu
(11.2 mg, 0.1 mmol, 1eq) was added to a mixture of imidazolinium salt 1 (49.2 mg, 0.1 mmol,
1eq) and [RuCl2(p-cymene)]2 (61 mg, 0.1 mmol, 1 eq.) in THF (1 ml). The resulting reaction
mixture was then stirred on a vortex mixer for 1 minute and subsequently 1H and
measurements were performed. In the
13
13
C NMR
C NMR analysis no Ru-C signal was observed. 1H
NMR and 13C NMR measurements after 18h showed no change of the signals.
NMR control experiment 2: In a flame-dried NMR tube and under inert atmosphere KOtBu
(3.4 mg, 30.4 μmol, 1eq) was added to a solution of imidazolinium salt 1 (15.0 mg, 30.4
μmol, 1eq) in THF (1 ml). The resulting reaction mixture was stirred on a vortex mixer for 1
minute and subsequently 1H and
product was observed. 1H and
13
13
C NMR measurements were performed. No dimerisation
C NMR measurements after 18h showed no change of the
signals.
NMR control experiment 3: In a flame-dried NMR tube and under inert atmosphere a 1M
solution of KOtBu (1eq) in THF was added dropwise over a period of 24h to a solution of
imidazolinium salt 1 (15.0 mg, 30.4 μmol, 1 eq.) in THF (1 ml). The resulting reaction
mixture was stirred on a vortex mixer for 1 minute and subsequently 1H and
13
measurements were performed. No dimerisation product was observed. 1H and
13
measurements after 18h showed no change of the signals.
S9
C NMR
C NMR