§ Experimental procedure: Butyllithium (1.2 mmol, hexane solution) was
added to a solution of 1 (1.0 mmol) in THF (2 mL) at 0 °C and the mixture
was stirred for 15 min. Alkyl halide (1.3 mmol for monohalide, 0.25 mmol
for dihalide) was added and the mixture was stirred for 0.5 h at rt. Aqueous
workup gave the crude product 2 or 5. A solution of 2 or 5 and HBF4·OEt2
(6 mmol, Et2O solution) in chloroform (5 mL) was refluxed for 12 h. The
mixture was passed through a short column of Na2SO4 and concentrated in
vacuo. The residue was dissolved in THF (1 mL) and MeOH (3 mL). TBAF
(8 mmol, THF solution), KHCO3 (8 mmol) and H2O2 (40 mmol, 30%
aqueous solution) were successively added and the mixture was stirred for
2 h at rt. The reaction mixture was poured into saturated aqueous NaHSO3
carefully and extracted with hexane. The combined organic layers were
dried over anhydrous Na2SO4 and concentrated in vacuo. Purification by
silica gel column chromatography provided 4 or 6.
The use of a dihaloalkane as an electrophile provided the
corresponding diketone in moderate yield (Table 2).
In summary, we have achieved the oxidation of gem-
disilylalkanes into the corresponding ketones. gem-Disilylalk-
anes are easily synthesized from 1,1-bis(dimethylphenylsilyl)-
ethene. Two alkyl groups are introduced from alkyllithiums and
alkyl halides respectively.
We thank Professor Tamejiro Hiyama (Kyoto University) for
helpful discussions. This work was supported by Grant-in-Aids
for Scientific Research from the Ministry of Education, Culture,
Sports, Science and Technology, Government of Japan. A. I.
acknowledges the Research Fellowships of the Japan Society
for the Promotion of Science for Young Scientists for financial
support.
1 For reviews, see: (a) E. W. Colvin, in Comprehensive Organic Synthesis,
ed. B. M. Trost and I. Fleming, Pergamon Press, Oxford, 1991, vol. 7,
p. 641; (b) I. Fleming, Chemtracts Org. Chem., 1996, 9, 1–64; (c) K.
Tamao, in Organosilicon and Bioorganosilicon Chemistry: Structure,
Bonding, Reactivity and Synthetic Application, ed. H. Sakurai, Halsted
Press, New York, 1985, p. 231; (d) K. Tamao, J. Synth. Org. Chem. Jpn.,
1988, 41, 861.
Notes and references
† 6,6-Bis(dimethylphenylsilyl)tetradecane (2a): Rf = 0.53 (hexane); IR
(neat) 2930, 2855, 1466, 1427, 1250, 1107, 808, 772, 735, 702 cm21; H
1
NMR (300 MHz, CDCl3) d 0.17 (s, 12H), 0.88 (t, J = 6.9 Hz, 3H), 0.89 (t,
J = 6.6 Hz, 3H), 1.14–1.37 (m, 18 H), 1.64–1.74 (m, 4 H), 7.23–7.35 (m,
6 H), 0.89 (dd, J = 1.8, 7.5 Hz, 4H); 13C NMR (75.3 MHz, CDCl3) d
21.37, 14.01, 14.04, 17.90, 22.50, 22.59, 26.00, 26.29, 29.24, 29.41, 30.83,
31.43, 31.47, 31.78, 33.09; Found: C, 77.38; H, 10.96%. Calcd for
C30H50Si2: C, 77.18; H, 10.79%.
2 A. Inoue, J. Kondo, H. Shinokubo and K. Oshima, Chem. Lett., 2001,
956.
3 (a) D. Seebach, R. Bürstinghaus, B.-Th. Gröbel and M. Kolb, Liebigs
Ann. Chem., 1977, 830–845; (b) A. Hirai, M. Nakamura and E.
Nakamura, J. Am. Chem. Soc., 2000, 122, 11791–11798; (c) P. Knochel,
M. C. P. Yeh and C. Xiao, Organometallics, 1989, 8, 2831–2835; (d) K.
Itami, K. Mitsudo and J. Yoshida, Angew. Chem., 2001, 113, 2399–2401;
Angew. Chem., Int. Ed., 2001, 40, 2337–2339; (e) M. P. Cooke Jr. and
R. K. Widener, J. Am. Chem. Soc., 1987, 109, 931–933.
4 (a) I. Fleming, R. Henning and H. Plaut, J. Chem. Soc., Chem. Commun.,
1984, 29–31; (b) S. H. Bergens, P. Noheda, J. Whelan and B. Bosnich,
J. Am. Chem. Soc., 1992, 114, 2121–2128.
‡ 6,6-Bis(fluorodimethylsilyl)tetradecane (3a): Rf = 0.40 (hexane); IR
(neat) 2930, 2856, 1468, 1379, 1258, 870, 827, 795, 762 cm21 1H NMR
;
(300 MHz, CDCl3) d 0.26 (d, J = 8.4 Hz, 12H), 0.88 (t, J = 6.9 Hz, 3H),
0.88 (t, J = 6.9 Hz, 3H), 1.20–1.38 (m, 18 H), 1.54–1.63 (m, 4 H); 13C NMR
(75.3 MHz, CDCl3) d 20.87 (d, J = 15.4 Hz), 13.98 (2C), 22.33, 22.57 (d,
J = 22.3 Hz), 26.14, 26.47, 29.03, 29.05, 29.24, 29.28, 30.73, 31.76, 32.93;
Found: C, 61.91; H, 11.78%. Calcd for C18H40F2Si2: C, 61.65; H,
11.50%.
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