in THF (2 ml) under argon. The solution was stirred for 5 minutes and
knowledge, this is also the first example of an NHC-complex of
Ag(I) being used in a catalytic process.
styrene (0.5 mmol) was then added. The mixture was stirred at ambient
temperature for 60 hours, and the conversion was determined by 1H NMR.
CAUTION: Workup must be carried out carefully owing to the risk of
explosion when using peroxides with THF. Afterwards, NaOH (3 M,
800 mL) and H2O2 (800 mL) were added and the mixture was stirred for
3 hours. After this time, 1 mL of saturated Na2S2O3 was added, followed
by 10 mL of NaOH (1 M). The reaction mixture was extracted into AcOEt
(3 6 25 mL) and washed with brine, dried over MgSO4, and the products
were characterized by chromatography and 1H NMR.
Additional improvements in the design of an asymmetrically
inductive Ag–NHC catalytic system are in progress and may bring
the reaction to the point where it becomes competitive with other
methods for this chemical synthesis.§"
The authors thank the CTQ2004-04412/BQU and the CICYT
(MAT2002-04421-C02-01) for financial support. J.R. thanks the
Generalitat de Catalunya for a fellowship.
1 T. B. Marder and N. C. Norman, Top. Catal., 1999, 5, 63.
2 T. Ishiyama and N. Miyaura, Chem. Rec., 2004, 3, 271.
3 R. T. Baker, P. Nguyen, T. B. Marder and S. A. Westcott, Angew.
Chem., Int. Ed. Engl., 1995, 34, 1336.
4 H. No¨th, Z. Naturforsch., Teil B, 1984, 39, 1463.
5 G. Lesley, T. B. Marder, N. C. Norman and C. R. Rice, Main Group
Chem. News, 1997, 5, 4.
6 C. Dai, E. G. Robins, A. J. Scott, W. Clegg, D. S. Yufit, J. A.
K. Howard and T. B. Marder, Chem. Commun., 1998, 1983;
J. B. Morgan, S. P. Miller and J. P. Morken, J. Am. Chem. Soc.,
2003, 125, 8702–8703.
Jesus Ram´ırez,a Rosa Corbera´n,b Mercedes Sanau´,c Eduardo Peris*b
and Elena Fernandez*a
aDepartament de Qu´ımica F´ısica i Inorga`nica, Universitat Rovira i
Virgili, Pc¸a. Imperial Ta`rraco 1, 43005, Tarragona, Spain.
E-mail: elenaf@quimica.urv.es; Fax: 34 977 559563; Tel: 34 977 558046
bDpt. Qu´ımica Inorga`nica i Orga`nica, Universitat Jaume I, Av Vicente
Sos Baynat s/n, 12080, Castello´n, Spain. E-mail: eperis@qio.uji.es
cDpt. Qu´ımica Inorga´nica, Universitat de Vale`ncia, 46100, Burjassot,
Spain
7 T. Ishiyama, M. Yamamoto and N. Miyaura, Chem. Commun., 1997,
689.
Notes and references
8 C. N. Iverson and M. R. Smith, III, Organometallics, 1997, 16, 2757.
9 D. Bourissou, O. Guerret, F. P. Gabbai and G. Bertrand, Chem. Rev.,
2000, 100, 39; K. J. Cavell and D. S. McGuinness, Coord. Chem. Rev.,
2004, 248, 671; E. Peris and R. H. Crabtree, C. R. Chim., 2003, 6, 33;
W. A. Herrmann, Angew. Chem., Int. Ed., 2002, 41, 1291;
A. J. Arduengo, Acc. Chem. Res., 1999, 32, 913; E. Peris and
R. H. Crabtree, Coord. Chem. Rev., 2004, 248, 2239.
10 I. J. B. Lin and C. S. Vasam, Comments Inorg. Chem., 2004, 25, 75.
11 K. M. Lee, H. M. J. Wang and I. J. B. Lin, J. Chem. Soc., Dalton
Trans., 2002, 2852.
12 Y. A. Wanniarachchi, M. A. Khan and L. M. Slaughter,
Organometallics, 2004, 23, 5881; A. Kascatan-Nebioglu, M. J. Panzner,
J. C. Garrison, C. A. Tessier and W. J. Youngs, Organometallics, 2004,
23, 1928; P. L. Arnold, A. C. Scarisbrick, A. J. Blake and C. Wilson,
Chem. Commun., 2001, 234.
13 H. M. J. Wang and I. J. B. Lin, Organometallics, 1998, 17, 972.
14 R. S. Simons, P. Custer, C. A. Tessier and W. J. Youngs,
Organometallics, 2003, 22, 1979; A. R. Chianese, X. W. Li,
M. C. Janzen, J. W. Faller and R. H. Crabtree, Organometallics,
2003, 22, 1663; J. A. Mata, A. R. Chianese, J. R. Miecznikowski,
M. Poyatos, E. Peris, J. W. Faller and R. H. Crabtree, Organometallics,
2004, 23, 1253.
{ Synthesis of 1-methyl-3-(+)-methylmenthoxide imidazolium chloride:
(+)-chloromethyl menthyl ether (1.1 mL, 5 mmol) was added to
N-methylimidazole (0.4 mL, 5 mmol) at room temperature with the ready
precipitation of a white solid. The solid was purified by precipitation with
CH2Cl2/ether. Yield: 1.315 g (92%). 1H NMR (CDCl3, 500 MHz) (menthyl
signals omitted): 11.07 (s, 1H, NCHN), 7.43 (s, 1H, imidazole-H), 7.41 (s,
1H, imidazole-H), 5.89 (d, 1H, -CHaHb-O), 5.66 (d, 1H, -CHaHb-O), 4.12
(s, 3H, CH3-imidazole). 13C NMR (DMSO-d6) (menthyl and CH3-
imidazole signals omitted): 138.00 (s, NCHN), 124.66 (s, imidazole), 122.93
(s, imidazole), 78.24 (s, -CH2-O). a 5 +0.5538u.
{ Synthesis of [(mentimid)2Ag]AgCl2, 4. Silver oxide (121 mg, 0.5 mmol)
was added to a solution of 1-methyl-3-(+)-methylmenthoxide imidazolium
chloride (200 mg, 0.7 mmol) in 10 mL of dichloromethane. The mixture
was stirred at room temperature for 4 h and then filtered through Celite.
The solvent was eliminated under vacuum and the resulting solid was the
pure compound 2-Ag. Yield: 200 mg (84%). 1H NMR (CDCl3, 300 MHz)
(menthyl signals omitted): 7.18 (s, 1H, imidazole-H), 7.02 (s, 1H, imidazole-
H), 5.52 (d, 1H, -CHaHb-O), 5.41 (d, 1H, -CHaHb-O), 3.85 (s, 3H, CH3-
imidazole). 13C NMR (CDCl3, 300 MHz) (menthyl and CH3-imidazole
signals omitted): 180.85 (s, C-Ag), 123.20 (s, imidazole), 121.18 (s,
imidazole), 78.61 (s, -CH2-O). a 5 +0.3022u. Electrospray MS. Cone
30 V. m/z (fragment): 609 [AgL2]+.
15 R. L. Thomas, F. E. S. Souza and T. B. Marder, J. Chem. Soc., Dalton
Trans., 2001, 1650.
16 T. B. Marder, N. C. Norman and C. R. Rice, Terahedron Lett., 1998,
39, 155; W. Clegg, T. R. F. Johann, T. B. Marder, N. C. Norman,
A. G. Orpen, T. M. Peakman, M. J. Quayle, C. R. Rice and A. J. Scott,
Dalton Trans., 1998, 1431.
17 N. Momiyama and H. Yamamoto, J. Am. Chem. Soc., 2004, 126, 5360;
Ch. Chen, X. Li and S. L. Schreiber, J. Am. Chem. Soc., 2003, 125,
10174.
§ Crystal data for 4: M 5 1574.79, triclinic, space group P1, a 5 9.3318(19),
˚
b 5 11.080(2), c 5 18.816(4) A, a 5 105.54(3), b 5 97.78(3), c 5 94.74(3)u,
V 5 1842.6(6) A , Z 5 1, Dc 5 1.419 g cm23, Mo-Ka radiation
3
˚
˚
(l 5 0.71073 A), 15440 reflections collected, 12817 unique, observed
reflections (I . 2.00s(I)), R 5 0.0601, Rw 5 0.1559. CCDC 264639. See
CIF or other electronic format.
" Typical catalytic diboration of styrene: Bis(catecholato)diboron
(0.55 mmol) was added to a solution of catalyst (5 mol%, 0.025 mmol)
3058 | Chem. Commun., 2005, 3056–3058
This journal is ß The Royal Society of Chemistry 2005