PAPER
One-Pot Synthesis of (Z)-a-Iodovinylsilanes
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HRMS: m/z calcd for C11H14INO2Si: 332.0093; found: 332.00680.
1,1-Dibromo-2-(4-methoxyphenyl)ethene (13)
N-Bromosuccinimide (0.89 g, 5.0 mmol) was added to a solution of
6 (0.32 g, 1.0 mmol) in MeCN (15 mL) and the suspension was
stirred at r.t. for 24 h. The solvent was evaporated and the mixture
was extracted with n-hexane (25 mL). The organic layer was con-
centrated and the product was purified by column chromatography
on silica gel, eluting with n-hexane–EtOAc (25:1) to give 13 as a
yellow solid; yield: 0.25 g (92%).
1H NMR (CDCl3): d = 3.83 (s, 3 H, OCH3), 6.90 (d, J = 8.8 Hz, 2
Harom), 7.41 (s, 1 H, C=CH), 7.52 (d, J = 8.8 Hz, 2 Harom).
13C NMR (CDCl3): d = 55.3, 87.2, 113.7, 129.8, 136.2, 144.0,
159.5.
1,1-Diiodo-2-(4-methoxyphenyl)ethene (10)
Bis(pyridine)iodonium tetrafluoroborate (1.49 g, 4.0 mmol) was
added to a solution of 1,1-bis(trimethylsilyl)-2-(4-methoxyphe-
nyl)ethene (0.28 g, 1.0 mmol) in MeCN (10 mL) and the suspen-
sion was stirred at r.t. for 24 h. The solvent was evaporated and the
mixture was extracted with n-hexane (25 mL). The organic layer
was concentrated and the product was purified by column chroma-
tography on silica gel, eluting with n-hexane–EtOAc (40:1) to give
10; yield: 0.37 g (97%); yellowish oil.
1H NMR (CDCl3): d = 3.82 (s, 3 H, OCH3), 6.89 (d, J = 8.8 Hz, 2
Harom), 7.43 (d, J = 8.2 Hz, 2 Harom), 8.10 (s, 1 H, C=CH).
13C NMR (CDCl3): d = 9.3, 55.3, 113.6, 129.2, 131.9, 150.2, 159.5.
MS (EI): m/z (%) = 292 (M+, 100), 89 (20), 63 (15).
HRMS: m/z calcd for C9H8Br2O: 289.8942; found: 289.8902.
MS (EI): m/z (%) = 386 (M+, 97), 132 (100), 117 (25), 89 (50), 63
(40).
Acknowledgment
HRMS: m/z calcd for C9H8I2O: 385.8665; found: 385.8685.
Financial support from the Ministry of Science and Higher Educa-
tion (Poland); Grant NN 204 238734 and PBZ KBN 118/T09 is
gratefully acknowledged
(Z,Z)-1,4-Bis(2-iodo-2-trimethylsilylvinyl)benzene (11)
N-Iodosuccinimide (0.52 g, 2.2 mmol) was added to a solution of
1,4-bis[2,2-bis(trimethylsilyl)ethenyl]benzene (0.53 g, 1.0 mmol)
in MeCN (10 mL) and the suspension was stirred at r.t. for 24 h. The
solvent was evaporated and the mixture was extracted with n-hex-
ane (30 mL). The organic layer was concentrated and the product
was purified by column chromatography on silica gel, eluting with
n-hexane–EtOAc (40:1), to give 11 as a white solid; yield: 0.47 g
(89%).
References
(1) (a) Colvin, E. W. Silicon Reagents in Organic Synthesis;
Academic Press: London, 1988. (b) Fleming, I.; Barbero,
A.; Walter, D. Chem. Rev. 1997, 97, 2063.
(2) (a) Zweifel, G.; Murray, R. E.; On, H. P. J. Org. Chem. 1981,
46, 1292. (b) Negishi, E.; Takahashi, T. J. Am. Chem. Soc.
1986, 108, 3402.
(3) Arefolov, A.; Langille, N. F.; Panek, J. S. Org. Lett. 2001, 3,
3281.
(4) Cooke, M. P.; Pollock, Ch. M. J. Org. Chem. 1993, 58, 7474.
(5) (a) Bratovanov, S.; Koźmiński, W.; Fässler, J.; Molnar, Z.;
Nanz, D.; Bienz, S. Organometallics 1997, 16, 3128.
(b) Anderson, J. C.; Munday, R. H. J. Org. Chem. 2004, 69,
8971.
(6) Cai, M.-Z.; Ye, X.-L.; Wang, P.-P. Synthesis 2005, 2654.
(7) Inoue, A.; Kitagawa, K.; Shinokubo, H.; Oshima, K. J. Org.
Chem. 2001, 66, 4333.
(8) Zweifel, G.; Lewis, W. J. Org. Chem. 1978, 43, 2739.
(9) (a) Cai, M.-Z.; Huang, J.-D.; Ye, X.-L.; Song, C.-S. J. Chem.
Res., Synop. 2003, 770. (b) Wipf, P.; Jahn, H. Tetrahedron
1996, 52, 12853.
(10) (a) Pawluc, P.; Marciniec, B.; Hreczycho, G.; Gaczewska,
B.; Itami, Y. J. Org. Chem. 2005, 70, 370. (b) Pawluc, P.;
Hreczycho, G.; Marciniec, B. J. Org. Chem. 2006, 71, 8676;
and references cited therein.
1H NMR (CDCl3): d = 0.28 [s, 18 H, 2 × Si(CH3)3], 7.28 (s, 2 H, 2
× C=CH), 7.62 (s, 4 Harom).
13C NMR (CDCl3): d = –1.3, 112.0, 128.2, 138.6, 143.7.
MS (EI): m/z (%): 526 (M+, 100), 199 (35), 73 (70).
HRMS: m/z calcd for C16H24I2Si2: 525.9506; found: 525.9480.
1-Bromo-2-(4-methoxyphenyl)-1-trimethylsilylethene (12)
To a solution of 6 (0.52 g, 1.6 mmol) in pentane (20 mL) was added
n-BuLi (1.5 mL, 2.4 mmol, 1.6 M in n-hexane) at –80 °C. The mix-
ture was stirred for 1.5 h and then quenched with a solution of Br2
in pentane (1.05 mL, 4.1 mmol, 4 M) at –80 °C. After 1 h, the mix-
ture was allowed to reach r.t. (3 h) and then aq sat. NH4Cl (25 mL)
was added. The crude product was extracted with Et2O (2 × 15 mL).
The combined organic layers were evaporated and the product was
purified by column chromatography on silica gel, eluting with
n-hexane–EtOAc (25:1) to give 12 as a mixture of isomers (E/Z =
1:3); yield: 0.40 g (89%); yellowish oil.
1H NMR (CDCl3): d = 0.07 [s, 6.75 H, Si(CH3)3, Z], 0.27 [s, 2.25 H,
Si(CH3)3, E], 3.82 (s, 2.25 H, OCH3, Z), 3.83 (s, 0.75 H, OCH3, E),
6.89 (d, J = 8.8 Hz, 0.5 Harom, Z), 6.90 (d, J = 8.8 Hz, 1.5 Harom, E),
7.14 (s, 0.75 H, C=CH, Z), 7.41 (s, 0.25 H, C=CH, E), 7.51 (d,
J = 9.1 Hz, 0.5 Harom, Z), 7.52 (d, J = 9.1 Hz, 1.5 Harom, E).
(11) Pawluc, P.; Hreczycho, G.; Walkowiak, J.; Marciniec, B.
Synlett 2007, 2061.
(12) Utilization of N-iodosuccinimide and bis(pyridine)iodonium
tetrafluoroborate in iododesilylation of simple vinylsilanes:
(a) Stamos, D. P.; Taylor, A. G.; Kishi, Y. Tetrahedron Lett.
1996, 37, 8647. (b) Barluenga, J.; Alvarez-Garcia, L. J.;
Gonzales, J. M. Tetrahedron Lett. 1995, 36, 2153.
(13) The synthesis of 1,1-dibromoalk-1-enes from 1-bromo-1-
trimethylsilylalk-1-enes has been reported: Fisher, R. P.; On,
H. P.; Snow, J. T.; Zweifel, G. Synthesis 1982, 127.
13C NMR (CDCl3): d = –1.8, 1.0, 55.2, 55.3, 113.4, 113.8, 127.3,
129.9, 130.8, 136.3, 137.4.
MS (EI): m/z (%) = 286 (M+, 100), 205 (60), 139 (50), 73 (65).
HRMS: m/z calcd for C12H17BrOSi: 284.0232; found: 284.0242.
Synthesis 2008, No. 22, 3687–3691 © Thieme Stuttgart · New York