LETTER
Demethylation of Methyl Aryl Ethers
1655
(
6) (a) Wheeler, C.; West, K. N.; Liotta, C. L.; Eckert, C. A.
2-Naphthol (Table 4, entry 2): pale pink solid (256 mg,
1
Chem. Commun. 2001, 887. (b) Judeh, Z. M. A.; Shen, H.
Y.; Chi, B. C.; Feng, L. C.; Selvasothi, S. Tetrahedron Lett.
89%). H NMR (500 MHz, CDCl ): d = 7.74–7.77 (m, 2 H),
3
7.67 (d, J = 8.5 Hz, 1 H), 7.43 (t, J = 7.5 Hz, 1 H), 7.32 (t,
J = 7.4 Hz, 1 H), 7.14 (d, J = 2.5 Hz, 1 H), 7.10 (dd, J = 2.5,
2
002, 43, 9381. (c) Lourenco, N. M. T.; Alfonso, C. M. A.
1
3
Tetrahedron Lett. 2003, 59, 789. (d) Chiappe, C.;
8.5 Hz, 1 H), 5.10 (s, 1 H). C NMR (125 MHz, CDCl ):
3
Pieraccini, D.; Saullo, P. J. Org. Chem. 2003, 68, 6710.
d = 153.6, 134.8, 130.1, 129.2, 128.0, 126.8, 126.6, 123.9,
+
(
e) Crowhurst, L.; Lancaster, N. L.; Arlandis, J. M. P.;
Welton, T. J. Am. Chem. Soc. 2004, 126, 11549.
f) Lancaster, N. L. Chem. Res. 2005, 413. (g) Landini, D.;
118.0, 109.7. MS (EI): m/z = 144 [M ].
4-Phenylphenol (Table 4, entry 3): white solid (333 mg,
1
(
98%). H NMR (500 MHz, CDCl ): d = 7.53–7.55 (m, 2 H),
3
Maia, A. Tetrahedron Lett. 2005, 46, 3961. (h) For a recent
review on nucleophilic substitution reaction in ionic liquids,
see:Jorapur, Y. R.; Chi, D. Y. Bull. Korean Chem. Soc. 2009,
7.46–7.49 (m, 2 H), 7.40–7.43 (m, 2 H), 7.29–7.32 (m, 1 H),
6.89–6.92 (m, 2 H), 5.10 (s, 1 H). C NMR (125 MHz,
1
3
CDCl ): d = 155.3, 141.0, 134.2, 129.0, 128.7, 127.0, 126.9,
3
+
27, 345.
115.9. MS (EI): m/z = 170 [M ].
(
(
7) Driver, G.; Johnson, K. E. Green Chem. 2003, 5, 163.
8) (a) Kemperman, G. J.; Roeters, T. A.; Hilberink, P. W. Eur.
J. Org. Chem. 2003, 1681. (b) Liu, T.; Hu, Y. Synth.
Commun. 2004, 34, 3209.
4-Hydroxyphenylphenylmethanone (Table 4, entry 4):
1
white solid (376 mg, 95%). H NMR (500 MHz, CDCl ):
3
d = 7.78 (d, J = 9.0 Hz, 2 H), 7.76 (d, J = 7.0 Hz, 2 H), 7.64
(s, 1 H), 7.58 (t, J = 7.5 Hz, 1 H), 7.48 (t, J = 8.0 Hz, 2 H),
1
3
(9) Boovanahalli, S. K.; Kim, D. W.; Chi, D. Y. J. Org. Chem.
6.95 (td, J = 2.0, 9.0 Hz, 2 H). C NMR (125 MHz, CDCl ):
3
2
004, 69, 3340.
10) Cheng, L.; Aw, C.; Ong, S. S.; Lu, X. Bull. Chem. Soc. Jpn.
007, 80, 2008.
d = 197.3, 161.2, 138.2, 133.5, 132.5, 130.2, 129.7, 128.6,
+
(
115.7. MS (EI): m/z = 198 [M ].
2
2¢-Hydroxyacetophenone (Table 4, entry 5): pale yellow
1
(
(
(
11) Chae, J. Arch. Pharm. Res. 2008, 31, 305.
oil (231 mg, 85%). H NMR (500 MHz, CDCl ): d = 12.27
3
12) Kappe, C. O. Angew. Chem. Int. Ed. 2004, 43, 6250.
13) (a) Brauman, J. I.; Olmstead, W. N.; Lieder, C. A. J. Am.
Chem. Soc. 1974, 96, 4030. (b) Olmstead, W. N.; Brauman,
J. I. J. Am. Chem. Soc. 1977, 99, 4219. (c) Tanaka, K.;
Mackay, G. I.; Payzant, J. D.; Bohme, D. K. Can. J. Chem.
(s, 1 H), 7.74 (ddd, J = 1.5, 2.5, 7.9 Hz, 1 H), 7.46–7.50 (m,
1 H), 6.98 (ddd, J = 1.5, 2.5, 8.3 Hz, 1 H), 6.89–6.93 (m, 1
1
3
H), 2.64 (s, 3 H). C NMR (125 MHz, CDCl ): d = 204.8,
3
162.6, 136.7, 131.0, 120.0, 119.2, 118.7, 26.9. MS (EI):
+
m/z = 136 [M ].
1
976, 54, 1643.
3¢-Hydroxyacetophenone (Table 4, entry 6): yellow solid
1
(
14) (a) Lancaster, N. L.; Welton, T.; Young, G. B. J. Chem. Soc.,
Perkin Trans. 2 2001, 2267. (b) Lancaster, N. L.; Salter, P.
A.; Welton, T.; Young, G. B. J. Org. Chem. 2002, 67, 8855.
15) Anne, G.; Glenn, A. G.; Jones, P. B. Tetrahedron Lett. 2004,
(250 mg, 92%). H NMR (500 MHz, CDCl ): d = 7.54 (t,
3
J = 2.5 Hz, 1 H), 7.51 (td, J = 1.0, 7.5 Hz, 1 H), 7.34 (t, J =
7.5 Hz, 1 H), 7.11 (ddd, J = 1.0, 2.5, 8.0 Hz, 1 H), 6.05 (br s,
1
3
(
(
1 H), 2.61 (s, 3 H). C NMR (125 MHz, CDCl ): d = 200.0,
3
45, 6967.
156.7, 138.5, 130.2, 121.3, 121.1, 114.9, 27.1. MS (EI):
+
16) All the reagents were purchased from Aldrich or TCI.
Column chromatography was performed on Silica gel 60
m/z = 136 [M ].
4¢-Hydroxyacetophenone (Table 4, entry 7): white solid
1
(230–400 mesh, Merck) and TLC was performed on silica
(267 mg, 98%). H NMR (500 MHz, CDCl ): d = 7.91 (d,
3
gel 60 F254 glass plate (Merck). Microwave reactions were
conducted on a CEM Discover® S-class instrument. H
NMR (500 MHz) and C NMR (125MHz) spectra were
recorded on a Varian 500 NMR spectrometer with chemical
shifts reported in ppm relative to residual solvent peaks or to
TMS as the internal standard. Yields refer to isolated yields
of compounds greater than 95% pure as determined by H
NMR and GC analyses. All compounds were characterized
by H NMR and C NMR. Gas chromatography analyses
were performed on a Hewlett Packard 6890 instrument with
HP-1 capillary column and mass spectra were recorded by
HP 5973 MSD with EI as the ionization method.
J = 8.5 Hz, 2 H), 6.91 (d, J = 8.5 Hz, 2 H), 6.66 (br s, 1 H),
2.59 (s, 3 H). C NMR (125 MHz, CDCl ): d = 198.9, 161.7,
131.5, 129.8, 115.8, 26.6. MS (EI): m/z = 136 [M ].
1
13
3
1
3
+
1
Estrone (Table 4, entry 8): white solid (286 mg, 53%). H
NMR (500 MHz, CDCl ): d = 7.16 (d, J = 8.5 Hz, 1 H), 6.65
3
(dd, J = 2.0, 9.0 Hz, 1 H), 6.59 (d, J = 2.0 Hz, 1 H), 4.74 (s,
1 H), 2.87 (dd, J = 3.5, 10.0 Hz, 2 H), 2.46 (q, J = 9.0 Hz, 1
H), 2.38 (t, J = 10.0 Hz, 1 H), 2.24 (m, 1 H), 1.91–2.21 (m,
4 H), 1.27–1.68 (m, 4 H), 1.25 (t, J = 7.0 Hz, 2 H), 0.91 (s, 3
1
1
13
1
3
H). C NMR (125 MHz, CDCl ): d = 221.5, 153.7, 138.3,
3
132.3, 126.8, 115.5, 113.1, 50.6, 48.3, 44.2, 38.6, 36.2, 31.8,
29.7, 26.7, 26.2, 21.8, 14.1. MS (EI): m/z = 270 [M ].
+
Representative Procedure: To a microwave tube were
added methyl aryl ether (2.0 mmol) and 1-n-butyl-3-
methylimidazolium bromide (1.32 g, 6.0 mmol). The
reaction tube was flushed with argon and then was irradiated
at 20 W for 40 min while cooled by air flow (power control
mode). After cooling to r.t., the reaction mixture was
acidified with 1 N HCl solution and extracted with EtOAc
4-Cyanophenol (Table 4, entry 9): white solid (217 mg,
1
91%). H NMR (500 MHz, CDCl ): d = 7.56 (d, J = 9.0 Hz,
3
1
3
2 H), 6.92 (d, J = 9.0 Hz, 2 H), 6.31 (br s, 1 H). C NMR
(125 MHz, CDCl ): d = 160.6, 134.6, 119.6, 116.8, 103.0.
3
+
MS (EI): m/z = 119 [M ].
a,a,a-Trifluoro-m-cresol (Table 4, entry 10): yellow oil
1
(305 mg, 94%). H NMR (500 MHz, CDCl ): d = 7.37 (t,
3
(
3 × 20 mL). The combined organic layer was washed with
J = 8.0 Hz, 1 H), 7.23 (d, J = 8.0 Hz, 1 H), 7.11 (s, 1 H), 7.03
(dd, J = 2.5, 8.0 Hz, 1 H), 5.39 (br s, 1 H). C NMR (125
1
3
H O, brine, dried over MgSO and the solvent was
2
4
evaporated under vacuum. Purification of the crude product
by column chromatography (EtOAc in n-hexane) afforded
the desired product.
MHz, CDCl ): d = 155.7, 132.3 (q, J = 32.0 Hz), 130.6, 124.0
3
(q, J = 270 Hz), 119.1 (d, J = 1.4 Hz), 118.0 (d, J = 4.1 Hz),
+
112.6 (d, J = 4.3 Hz). MS (EI): m/z = 162 [M ].
1
9
7
1
-Naphthol (Table 4, entry 1): pale pink solid (265 mg,
3-Bromophenol (Table 4, entry 11): yellow solid (320 mg,
1
1
2%). H NMR (500 MHz, CDCl ): d = 8.15–8.20 (m, 1 H),
93%). H NMR (500 MHz, CDCl ): d = 7.10 (t, J = 8.0 Hz,
3
3
.79–7.82 (m, 1 H), 7.46–7.51 (m, 2 H), 7.44 (d, J = 8.0 Hz,
H), 7.30 (t, J = 8.0 Hz, 1 H), 6.80 (d, J = 8.0 Hz, 1 H), 5.34
1 H), 7.05–7.08 (m, 1 H), 7.02 (t, J = 2.0 Hz, 1 H), 6.76–6.78
1
3
(m, 1 H), 5.24 (s, 1 H). C NMR (125 MHz, CDCl ): d =
3
(
s, 1 H). 13C NMR (125 MHz, CDCl ): d = 151.6, 135.0,
156.6, 131.1, 124.2, 123.0, 119.1, 114.5. MS (EI): m/z = 172
3
+
127.9, 126.7, 126.1, 125.5, 124.6, 121.8, 120.9, 108.9. MS
[M ].
+
(
EI): m/z = 144 [M ].
Synlett 2010, No. 11, 1651–1656 © Thieme Stuttgart · New York