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R. Ghorbani-Vaghei et al. / Tetrahedron Letters 47 (2006) 4505–4508
1
5 mL CH Cl ) over 5 min at room temperature. The
a power output of 900 W (LG Co. microwave,
230 V ꢁ 50 Hz, RF output 900 W). After completion of
the reaction, [3–8 min, Table 1, monitored by TLC (9:1,
carbon tetrachloride/acetone)], CH Cl (15 mL) was
2
2
reaction was monitored by TLC (9:1, carbon tetrachlo-
ride/acetone). After completion of the reaction, the
reagent was filtered and the organic phase was washed
with Na CO solution (10 mL, 5%), H O (10 mL) and
2
2
added, and the reagent was removed by filtration. The or-
ganic phase was washed with Na CO solution (10 mL,
2
3
2
dried (MgSO ). Evaporation of the solvent under
4
2
3
reduced pressure gave the product. Further purification
was achieved by distillation or recrystallization to afford
pure silyl ethers (Table 1).
5%), H O (10 mL), and dried (MgSO ). Evaporation of
2
4
the solvent under reduced pressure gave the product.
Further purification was achieved by distillation or
recrystallization to afford pure silyl ethers (Table 1).
C H SSi (entry 11): IR (KBr): m 3090, 2959, 1614, 1250
9
14
ꢀ
1 1
(
S-TMS) cm ; H NMR [(CD ) CO, FT-90 MHz]: d
3 2
7
.30–7.50 (m, 5H, aromatic), 0.05 [s, 9H (TMS)].
References and notes
C H SSi (entry 12): IR (KBr): m 3022, 2954, 1490, 1249
1
0
16
1
2
. (a) Greene, T. W.; Wuts, P. G. M. Protective Groups in
Organic Synthesis, 3rd ed.; John Wiley & Sons: New York,
ꢀ
1 1
(
S-TMS) cm ; H NMR [(CD ) CO, FT-90 MHz]: d
3 2
7
.00–7.40 (m, 4H, aromatic), 2.20 (s, 3H), 0.05 [s, 9H
1
999; p 116; (b) Sartori, G.; Ballini, R.; Bigi, F.; Bosica,
(
TMS)].
G.; Maggi, R.; Righi, P. Chem. Rev. 2004, 104, 199.
. Cooper, B. E. Chem. Ind. 1978, 794.
C H SSi (entry 13): IR (KBr): m 3056, 2910, 1462, 1252
3. Langer, S. H.; Connell, S.; Wender, I. J. Org. Chem. 1958,
23, 50.
1
3
16
ꢀ
1 1
(
S-TMS) cm ; H NMR [(CD ) CO, FT-90 MHz]: d
3 2
4
5
6
7
. Bandgar, B. P.; Chavare, S. N.; Pandit, S. S. J. Chin.
Chem. Soc. 2005, 52, 125.
. Firouzabadi, H.; Karimi, B. Synth. Commun. 1993, 23,
7
.20–7.80 (m, 7H, aromatic), 0.03 [s, 9H (TMS)].
1
633.
3
. General method for solvent-free silylation of alcohols
and phenols using HMDS and PBBS
. Firouzabadi, H.; Sardarian, A. R.; Khayat, Z.; Karimi, B.;
Tangestaninejad, S. Synth. Commun. 1997, 27, 2709.
. Zhang, Z.-H.; Li, T.-S.; Yang, F.; Fu, C.-G. Synth.
Commun. 1998, 28, 3105.
Alcohol or phenol (1 mmol), PBBS (0.2 g) and HMDS
1.5 mmol) were added to a mortar and the mixture
(
8. Curini, M.; Epifano, F.; Marcotullio, M. C.; Rosati, O.
Synth. Commun. 1999, 29, 541.
9. Karimi, B.; Golshani, B. J. Org. Chem. 2000, 65, 7228.
0. Firouzabadi, H.; Iranpoor, N.; Amani, K.; Nowrouzi, F.
J. Chem. Soc., Perkin Trans. 1 2002, 2601.
1. Azizi, N.; Saidi, M. R. Organometallics 2004, 23, 1457.
2. Akhlaghinia, B.; Tavakoli, S. Synthesis 2005, 1775.
3. Bruynes, A. C.; Jurriens, T. K. S. J. Org. Chem. 1982, 47,
was pulverized vigorously with a pestle. A spontaneous
reaction took place [3–6 min, Table 1, monitored by
TLC (9:1, carbon tetrachloride/acetone)]. After comple-
tion of the reaction, CH Cl (15 mL) was added, and the
1
2
2
1
1
1
reagent was removed by filtration. The organic phase
was washed with Na CO solution (10 mL, 5%) and
2
3
H O (10 mL), and dried (MgSO ). Evaporation of the
2
4
3
966.
solvent under reduced pressure gave the product. Fur-
ther purification was achieved by distillation or recrys-
tallization to afford pure silyl ethers (Table 1).
1
4. Uppadhya, T. T.; Daniel, T.; Sudalai, A.; Ravindra-
nathan, T.; Sabu, K. R. Synth. Commun. 1996, 26, 4539.
15. Ghorbani-Vaghei, R.; Galili, H. Synthesis 2005, 1099.
1
6. (a) Ghorbani-Vaghei, R.; Shahbazee, E. J. Braz. Chem.
Soc. 2005, 16, 647; (b) Ghorbani-Vaghei, R.; Azarifar, D.;
Maleki, B. Bull. Korean Chem. Soc. 2004, 25, 953; (c)
Ghorbani-Vaghei, R. Tetrahedron Lett. 2003, 44, 7529; (d)
Ghorbani-Vaghei, R.; Khazaei, A. Tetrahedron Lett. 2003,
4
. General method for the silylation of alcohols and
phenols using HMDS with PBBS under microwave
irradiation
4
4, 7525.
1
1
7. Tillu, V. H.; Jadhav, V. H.; Borate, H. B.; Wakharkar, R.
D. ARKIVOC 2004, 14, 83.
8. (a) Shirini, F.; Zolfigol, M. A.; Mohammadi, K. Phos-
phorus, Sulfur, Silicon 2003, 178, 1567; (b) Shirini, F.;
Zolfigol, M. A.; Abedini, M. Phosphorus, Sulfur, Silicon
2005, 180, 2299.
Alcohol or phenol (1 mmol), PBBS (0.15 g), and HMDS
(
(
1.5 mmol) were added to a round-bottomed flask
25 mL). The flask was placed in a bath containing
SiO to enable absorption of additional microwave irra-
2
diation. The flask was irradiated in a microwave oven at