7
168
M. Sridhar et al. / Tetrahedron Letters 50 (2009) 7166–7168
NMR (CDCl
À1
New Directions of Silicon Chemistry for Obtaining Bioactive Compound In
Silicon Chemistry; Cory, J. Y., Corey, E. R., Eds.; Ellis Horwood Ltd: England, 1988;
pp 135–144. Chapter 13.
3
, 75 MHz) d = 139.7, 137.5, 132.6, 128.5, 21.8, 1.0; IR (Neat, cm+ ): m
3056, 2967, 1426, 1245, 1108, 1050, 837, 789; EIMS (m/z, %): 314 (M , 23),
299(65), 267(25), 225(20), 223(35), 207(84), 179(24), 149(32), 93(54), 77(23),
4
.
.
.
.
.
.
Napier, S.; Marcuccio, S. M.; Tye, H.; Whittaker, M. Tetrahedron Lett. 2008, 49,
57(27), 43(100). Exact mass observed for
314.1522).
18 2
C H26OSi : 314.1514 (calcd:
3
939–3942.
5
6
7
8
9
Sore, H. F.; Boehner, C. M.; MacDonald, S. J. F.; Norton, D.; Fox, D. J.; Spring, D. R.
Org. Biomol. Chem. 2009, 7, 1068–1071.
Mézailles, N.; Maigrot, N.; Hamon, S.; Ricard, L.; Mathey, F.; Floch, P. L. J. Org.
Chem. 2001, 66, 1054–1056.
(a) Grubb, W. T. J. Am. Chem. Soc. 1954, 76, 3408–3414; b Maass, G.; Lucking, H.
J.; Buchner, W.; Degen, B. U.S. Patent 4,060,537, 1977.
Minoru, T.; Toshio, S.; Yoshiaki, N. G.B. Patent 1,435, 465, 1976; Chem. Abstr.
Study of the reusability of the catalyst: The recovered bottom layer obtained
above was InBr –THF complex, which was in the form of a viscous liquid. It was
thoroughly washed with hexane (3 Â 5 ml) and dried under vacuum to obtain
[InBr ] in the form of a white powder (135 mg). 50 mg of InBr
3
3
Á(THF)
2
3
Á(THF)
2
obtained as above was taken into a 25 ml r.b. flask and to this, dimethyl-p-tolyl
silane 1l (0.4 g, 2.6 mmol) and THF (5 ml) were added and stirred for 4 h at
room temperature keeping open to air. After the completion of the reaction,
0.38 g (92%) of disiloxane 2l was obtained upon purification and its spectral
data were identical to that obtained above.Study of the reusability of the catalyst:
1
975, 82, 4411.
Typical procedure for Lewis acid-catalyzed air oxidation of hydrosilane to
disiloxane: Dimethyl-p-tolyl silane 1l (1.0 g, 6.7 mmol), InBr (118 mg,
.33 mmol), and tetrahydrofuran (10 ml) were taken in 25 ml round-
3
The recovered bottom layer obtained above was InBr
was in the form of a viscous liquid. It was thoroughly washed with hexane
(3 Â 5 ml) and dried under vacuum to obtain [InBr Á(THF) ] in the form of a
white powder (135 mg). 50 mg of InBr obtained as above was taken
3
–THF complex, which
0
a
bottomed flask and stirred for 4 h at room temperature keeping the reaction
open to air. The reaction proceeded with the evolution of hydrogen gas bubbles
3
2
3
Á(THF)
2
(
The isolated gas gave a positive ‘pop’ test with lit splinter). After completion of
into a 25 ml r.b. flask and to this, dimethyl-p-tolyl silane 1l (0.4 g, 2.6 mmol)
and THF (5 ml) were added and stirred for 4 h at room temperature keeping
open to air. After completion of the reaction, 0.38 g (92%) of disiloxane 2l was
obtained upon purification and its spectral data were identical to that obtained
above.
the reaction (TLC), the solvent was removed under reduced pressure. The
resulting mixture was separated into two liquid layers. The upper layer was
found to be the desired disiloxane, which is miscible in hexane and the bottom
3
layer was InBr –THF complex, which is not miscible with hexane. Hence, the
crude product was extracted with hexane (4 Â 5 ml) from this bi-layer mixture
and concentrated under reduced pressure. Purification of the crude product by
column chromatography (silica gel 100–200 mesh, hexane) gave 1,3,3-
10. InBr
3
forms stable solid complex [InBr
3
Á(THF)
2
] upon treatment with THF. Ref.:
Willey, G. R.; Aris, D. R.; Haslop, J. V.; Errington, W. Polyhedron 2001, 20, 423–
429.
tetramethyl-1,3-di-p-tolyl-disiloxane 2l (1.02 g, 98%) as a colorless oil. The
11. Berberova, N. T. Russ. J. Electrochem. 2000, 36, 174–182.
12. (a) Haynes, R. K. Aust. J. Chem. 1978, 31, 121–129; (b) Haynes, R. K. Aust. J. Chem.
1978, 31, 131–138.
1
spectral data obtained for 2l is as follows: H NMR (CDCl
3
, 300 MHz): d = 7.3–
13
7
.4 (d, J = 7.6 Hz, 4H), 7.1–7.1(d, J = 7.6 Hz, 4H), 2.3 (s, 6H), 0.3 (br s, 12H);
C