9
00
An Efficient and Chemoselective Deprotection of Aryl tert-Butyldimethylsilyl (TBDMS) Ethers by NaCN J. Braz. Chem. Soc.
(
ESI-MS) analyses was recorded in anAgilent 1100 Series
1-Bromo-4-[[(1,1-dimethylethyl)dimethylsilyl]oxy]benzene
MSD Trap SL (Santa Clara, CA, USA). The reactions
were monitored by thin-layer chromatography (TLC;
HG/T2354-92, GF254), and the products were purified
by column chromatography on silica gel (200-300 mesh)
made by Qingdao Puke Parting Materials Co., Ltd.
(2)
1
H NMR (400 MHz, CDCl ) d 7.32 (d, 2H, J 9.2 Hz,
3
Ar-H), 6.90 (d, 2H, J 9.2 Hz, Ar-H), 0.97 (t, 9H, J 2.8 Hz,
CH ), 0.18 (t, 6H, J 2.8 Hz, CH ).
25
3
3
(
Qingdao, China).
1-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]-3-methylbenzene
3)
(
1
Typical experimental procedure for preparation of tert-
H NMR (400 MHz, CDCl ) d 7.12 (d, 1H, J 7.6 Hz,
3
butyldimethylsilyl ethers
Ar-H), 7.05 (t, 1H, J 6.4 Hz, Ar-H), 6.85 (t, 1H, J 6.4 Hz,
Ar-H), 6.75 (d, 1H, J 7.6 Hz,Ar-H), 2.21 (s, 3H, CH ), 1.02
3
All the tert-butyldimethylsilyl ethers were prepared as
previously reported in the respective literature. Taking the
-[[(1, 1-dimethylethyl)dimethylsilyl]oxy]-4-nitrobenzene
(t, 9H, J 2.8 Hz, CH ), 0.21 (t, 6H, J 2.8 Hz, CH ), ESI-MS
m/z: 261.2 [M + K] .
3
+ 26
3
23
1
for example, a 100 mL three-neck flask was equipped with
a thermometer, condenser. Chloro(1,1-dimethylethyl)
dimethylsilane (2.1 g, 14 mmol) and imidazole (0.476 g,
1-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]-3-fluorobenzene (4)
1
H NMR (400 MHz, CDCl ) d 7.99-7.97 (m, 1H,
3
Ar-H), 7.85-7.83 (m, 1H, Ar-H), 7.53-7.50 (m, 1H, Ar-H),
7
1
mmol) were added into a mixture of 4-nitrophenol (3 g,
6.99-6.90 (m, 1H, Ar-H), 1.00 (t, 9H, J 2.8 Hz, CH ), 0.19
(t, 6H, J 2.4 Hz, CH3).
3
4 mmol) in 20 mL of N,N-dimethylformamide (DMF).
o
Then, the mixture was continually stirred at 50 C and the
reaction progress was monitored by TLC.After completion,
the reaction mixture was concentrated in vacuo to obtain
crude product, which was purified by silica column
chromatography. Other tert-butyldimethylsilyl ethers were
prepared in similar methods.
1-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]-2-methylbenzene
(5)
1
H NMR (400 MHz, CDCl ) d 7.12 (d, 1H, J 8 Hz,
3
Ar-H), 7.07-7.03 (m, 1H, Ar-H), 6.87-6.83 (m, 1H, Ar-H),
6.76 (d, 1H, J 8.0 Hz, Ar-H), 2.21 (s, 3H, CH ), 1.02 (t,
3
9
H, J 2.8 Hz, CH ), 0.21 (t, 6H, J 2.8 Hz, CH ), ESI-MS
3 3
+
Typical experimental procedure for deprotection of tert-
m/z: 261.2 [M + K] .
butyldimethylsilyl ethers
1
-[[(1, 1-Dimethylethyl)dimethylsilyl]oxy]-4-
Also taking the 1-[[(1,1-dimethylethyl)dimethylsilyl]
oxy]-4-nitrobenzene for example, a 100 mL three-neck
flask was equipped with a thermometer, condenser.
NaCN (0.04 g, 0.8 mmol) was added into a mixture of
trifluoromethoxybenzene (6)
1
H NMR (400 MHz, CDCl ) d 7.07 (d, 2H, J 8.4 Hz,
3
Ar-H), 6.90 (d, 2H, J 9.2 Hz, Ar-H), 0.98 (t, 9H, J 2.8 Hz,
CH ), 0.20 (t, 6H, J 2.8 Hz, CH ).
3
3
1-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-4-nitrobenzene
(
(
3
2 g, 8 mmol) in anhydrous ethanol (15 mL) and H O
1-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]-2-(trifluoromethyl)
2
1 mL). Then, the mixture was continually stirred at
benzene (7)
o
1
0 C and the reaction progress was monitored by TLC.
H NMR (400 MHz, CDCl ,) d 7.55 (dd, 1H, J 1.2,
3
After completion, the reaction mixture was concentrated
in vacuo, and then the residue was dissolved in water,
extracted with dichloromethane three times. The
combined organic layer was washed with saturated
sodium chloride solution and dried over anhydrous
sodium sulfate. After, the desiccant was filtered off, the
filtrate was evaporated to obtain crude product, which
was purified by column chromatography on silica gel
8 Hz,Ar-H), 7.40-7.35 (m, 1H,Ar-H), 6.97 (t, 1H, J 7.6 Hz,
Ar-H), 6.91 (d, 1H, J 8 Hz, Ar-H), 1.01 (t, 9H, J 2.8 Hz,
CH ), 0.27 (t, 6H, J 2.8, CH ).
3
3
1-Bromo-2-chlorophenoxy-4-[[(1,1-dimethylethyl)dimethyl-
silyl]oxy]benzene (8)
1
H NMR (400 MHz, CDCl ) d 7.51 (d, 1H, J 2.4 Hz,
3
Ar-H), 7.13 (q, 1H, J 2.8, 8.8 Hz, Ar-H), 6.79 (d, 1H,
(
86.4% yield).
J 8.8 Hz, Ar-H), 1.03 (t, 9H, J 2.8 Hz, CH ), 0.24 (t, 6H,
3
J 2.8 Hz, CH3).
1
-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]-4-nitrobenzene (1)
1
H NMR (400 MHz, CDCl ) d 8.16 (d, 2H, J 9.2 Hz,
N-[4-[[(1,1-Dimethylethyl)dimethylsilyl]oxy]phenyl]
3
Ar-H), 6.90 (d, 2H, J 9.2 Hz, Ar-H), 1.00 (t, 9H, J 2, CH ),
acetamide (9)
3
24
1
0
.26 (t, 6H, J 1.2 Hz, CH3).
H NMR (400 MHz, CDCl ) d 7.33 (d, 2H, J 8.8 Hz,
3