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2006, 691, 3027–3036; (b) Karimi, B.; Enders, D. Org.
Lett. 2006, 8, 1237–1240.
7. (a) Albrecht, M.; Stoeckli-Evans, H. Chem. Commun.
2005, 4705–4707; (b) Wang, R.; Twamley, B.; Shreeve, J.
M. J. Org. Chem. 2006, 71, 426–429.
8. (a) Hesemann, P.; Moreau, J. J. E. Tetrahedron: Asym-
metry 2000, 11, 2183–2194; (b) Ciriminna, R.; Hesemann,
P.; Moreau, J. J. E.; Carraro, M.; Campestrini, S.;
Pagliaro, M. Chem. Eur. J. 2006, 12, 5220–5224.
9. (a) Gadenne, B.; Hesemann, P.; Moreau, J. J. E. Chem.
Commun. 2004, 1768–1769; (b) Gadenne, B.; Hesemann,
P.; Polshettiwar, V.; Moreau, J. J. E. Eur. J. Inorg. Chem.
2006, 3697–3702.
12. To a solution of 0.67 g of Pd(OAc)2 (0.003 mol) in 100 ml
dry THF, 3.9 g of 1,3-N,N-bis(3-(triethoxysilyl)propyl)-
imidazolium iodide (2) (0.006 mol) was added and the
reaction mixture was stirred at room temperature for 1 h
and then refluxed for 6 h. The formation of Pd–carbene
complex can be checked by in situ NMR. After comple-
tion, THF was evaporated to yield the crude oily product
which solidified after tituration with pentane, yielding
3.5 g of orange coloured Pd–carbene complex 3 (88%).
FT-IR (KBr): 3121, 2974, 2929, 2885, 1458, 1079, 949,
1
794, 713 cmÀ1; H NMR (CDCl3): d 0.6 (8H, m), 1.16 (t,
36H, J = 7.2 Hz), 2.1 (8H, m), 3.77 (24H, q, J = 7.2 Hz),
4.3 (8H, m), 7.87 (4H, s) ppm; 13C NMR (CDCl3): d 7.62,
18.32, 23.5, 53.3, 58.46, 121, 167, ppm; MS (FAB+) (%):
1314 (M+, 3); 1266 (MÀEtOÀ, 7); 1184 (MÀIÀ, 46); 477
(100).
10. (a) Xu, L.; Chen, W.; Xiao, J. Organometallics 2000, 19,
1123–1127; (b) Xiao, J. C.; Twamley, B.; Shreeve, J. M.
Org. Lett. 2004, 6, 3845–3847.
´
11. The synthesis of a similar bis-trimethoxysilyl-imidazolium
precursor was already reported: Cazin, C. S. J.; Veith, M.;
Braunstein, P.; Bedford, R. B. Synthesis 2005, 622–626;
Synthesis of a bis-silylated dihydroimidazolium precursor:
Lee, B.; Im, H. J.; Luo, H.; Hagaman, E. W.; Dai, S.
Langmuir 2005, 21, 5372–5376, N-3-Propylimidazole tri-
ethoxysilane (1) 2.72 g (0.01 mol) and 3-iodopropyl trieth-
oxysilane 4.3 g (0.013 mol) were dissolved in 10 ml of
acetonitrile in a Schlenk tube. The reaction mixture was
stirred under inert atmosphere at 80 °C for 24 h. After
completion, the solvent was evaporated and the product
was washed with ether to remove excess of 3-iodopropyl
triethoxysilane, yielding 5.8 g (96%) of the pure product.
FT-IR (KBr): 3070, 2972, 2922, 2885, 1562, 1445, 1294,
1163, 1076, 956, 783, 639 cmÀ1; 1H NMR (CDCl3): d 0.48
(4H, t, J = 8 Hz), 1.07 (t, 18H, J = 7.2 Hz), 1.89 (4H, m),
3.67 (12H, q, J = 7.2 Hz), 4.24 (4H, t, J = 7.2 Hz), 7.33
(2H, s), 9.85 (1H, s) ppm; 13C NMR (CDCl3): d 7.1, 18.3,
24.4, 51.8, 58.6, 122.3, 135 ppm; MS (FAB+): (M+) 477;
HRMS (FAB+): Calcd for C21H45N2O6Si2 (M+) 477.2816;
found, 477.2824.
13. Corriu, R. J. P.; Moreau, J. J. E.; Thepot, P.; Wong Chi
Man, M. Chem. Mater. 1992, 4, 1217–1224.
14. The catalytic organic silica was synthesized by slightly
modified classical conditions. The Pd–carbene complex (3)
(3.5 g, 2.7 mmol) was dissolved in 5 ml of THF and 0.6 ml
of water was added. To this solution, 0.6 ml of 1 N NH4F
was added with stirring at room temperature. Gelification
occurred within 10 min. The gel was allowed to stand for 2
days. After this time, the solid was washed with ethanol
and acetone and dried under vacuum at 90 °C for 6 h to
yield 2.6 g of orange coloured silica (4). FT-IR (KBr):
3120, 2930, 2863, 1126, 1001, 876, 691 cmÀ1 29Si CP-
;
MAS: d À59 (T2), À66 (T3) ppm, 13C CP-MAS: d 11, 18,
24 53, 57, 128, 166 ppm; BET: Surface area 5 m2/g;
elemental analysis/% C, 22,40; H, 3.79; N, 4.67; I, 22.08;
Pd, 8.62; Si, 11.87.
15. (a) Molnar, A.; Papp, A. Synlett 2006, 3130–3134; (b)
Pro¨ckl, S. S.; Kleist, W.; Ko¨hler, K. Tetrahedron 2005, 61,
9855–9859.
16. Polshettiwar, V.; Hesemann, P.; Moreau, J. J. E. Tetra-
hedron 2007, 63, 6784–6790.