Sodium Bisulfite: An Efficient Catalyst for Ether Formation
(CDCl3, 400 MHz) δ: 1.34 (d, J=6.4 Hz, 6H), 4.17 (q,
J=6.8 Hz, 2H), 7.16—7.33 (m, 8H).
1-((4-Fluorophenyl)((4-fluorophenyl)(4-methoxy-
phenyl)methoxy)methyl)-4-methoxybenzene (5c)
1
5-(((1,3-Dihydroisobenzofuran-5-yl)methoxy)-
methyl)-1,3-dihydroisobenzofuran (3e) White solid,
Yellow oil, 92% yield; H NMR (CDCl3, 400 MHz) δ:
3.78 (s, 3H), 3.79 (s, 3H), 5.29 (s, 2H), 6.84—6.88 (m,
4H), 6.96—7.02 (m, 4H), 7.20—7.23 (m, 4H), 7.27—
7.31 (m, 4H); 13C NMR (CDCl3, 125 MHz) δ: 54.93,
78.84, 113.78, 113.86, 114.92, 115.02, 115.09, 115.20,
128.49, 128.33, 133.69, 133.97, 138.14, 138.41, 159.02,
159.10, 160.93, 161.00, 162.88, 162.96. HRMS calcd
for [C28H24F2O3Na]+ 469.1586, found 469.1590.
1
m.p. 40—41 ℃ (Lit.15 41—43 ℃), 79% yield; H
NMR (CDCl3, 400 MHz) δ: 4.42 (s, 4H), 5.94 (s, 4H),
6.76—6.79 (m, 4H), 6.86 (s, 2H).
General procedure for compounds 3f— 3h
A mixture of 1-(4-methoxyphenyl)ethanol (1c) (310
mg, 2.0 mmol), 1-butanol (590 mg, 8.0 mmol) and Na-
HSO3 (0.6 mg, 0.006 mmol) was stirred at 110 ℃ for 1
h. After the reaction finished, the residue was purified
by column chromatography on silica gel to give the
corresponding ether 3f in 80% isolated yield.
(Bis(4-fluorophenyl)methoxy)bis(4-fluorophen-
yl)methane (5d) White solid, m.p. 78—79 ℃, 95%
1
yield; H NMR (CDCl3, 400 MHz) δ: 5.30 (s, 2H),
6.99—7.04 (m, 8H), 7.25—7.28 (m, 8H); 13C NMR
(CDCl3, 125 MHz) δ: 78.88, 115.32, 115.50, 128.70,
128.76, 137.45, 161.25, 163.21. HRMS calcd for
[C28H18F4ONa]+ 469.1186, found 469.1199.
1-(1-Butoxyethyl)-4-methoxybenzene (3f)2i Col-
1
orless oil, 80% yield; H NMR (CDCl3, 400 MHz) δ:
0.88 (t, J=7.2 Hz, 3H), 1.35—1.42 (m, 2H), 1.41 (d,
J=6.4 Hz, 3H), 1.51—1.60 (m, 2H), 3.26 (t, J=6.8 Hz,
2H), 3.80 (s, 3H), 4.34 (q, J=6.4 Hz, 1H), 6.88 (d, J=
8.4 Hz, 2H), 7.23 (d, J=8.4 Hz, 2H).
1-((4-Chlorophenyl)((4-chlorophenyl)(p-tolyl)-
methoxy)methyl)-4-methylbenzene (5e) Yellow oil,
94% yield; 1H NMR (CDCl3, 400 MHz) δ: 2.32 (s, 3H),
2.33 (s, 3H), 5.29 (s, 2H), 7.12—7.20 (m, 8H), 7.24—
7.27 (m, 8H); 13C NMR (CDCl3, 125 MHz) δ: 21.02,
79.20, 127.00, 127.18, 128.24, 128.38, 128.49, 129.15,
129.23, 132.94, 133.07, 137.27, 137.40, 138.28, 138.53,
140.72, 140.96. HRMS calcd for [C28H24Cl2ONa] +
469.1096, found 469.1094.
1-(1-(Heptyloxy)ethyl)-4-methoxybenzene
(3g)
Colorless oil, 85% yield; 1H NMR (CDCl3, 400 MHz) δ:
0.90 (t, J=6.4 Hz, 3H), 1.27—1.35 (m, 6H), 1.42 (d,
J=6.4 Hz, 3H), 1.47—1.59 (m, 4H), 3.27 (t, J=6.4 Hz,
2H), 3.82 (s, 3H), 4.36 (q, J=6.4 Hz, 1H), 6.89 (d, J=
8.8 Hz, 2H), 7.26 (d, J=8.8 Hz, 2H); 13C NMR (CDCl3,
125 MHz) δ: 13.82, 22.40, 23.93, 25.98, 28.95, 29.78,
21.63, 54.67, 68.18, 77.25, 113.41, 126.96, 135.06,
158.65. HRMS calcd for [C16H26O2Na]+ 273.1825,
found 273.1810.
Conclusions
In conclusion, we have developed a simple and effi-
cient protocol for the synthesis of symmetric and un-
symmetric ethers via direct dehydration of benzyl alco-
hols containing β-hydrogens by applying cheap Na-
HSO3 as a catalyst under solvent-free conditions. The
etherification of benzhydryl alcohols catalyzed with
NaHSO3 is also explored. Further studies on NaHSO3
catalyzing C—C, C—O and C—N bond formations are
ongoing in our laboratory.
1-(1-(Heptyloxy)ethyl)-4-methoxybenzene (3h)
Colorless oil, 83% yield; 1H NMR (CDCl3, 400 MHz) δ:
0.92 (d, J=6.4 Hz, 6H), 1.41 (d, J=6.4 Hz, 3H),
1.52—1.57 (m, 1H), 1.64—1.75 (m, 2H), 3.44 (dt, J=
6.4, 10.8 Hz, 1H), 3.50 (dt, J=6.0, 10.6 Hz, 1H), 3.80
(s, 3H), 4.32 (q, J=6.4 Hz, 1H), 6.88 (d, J=8.4 Hz,
2H), 7.23 (d, J=8.4 Hz, 2H); 13C NMR (CDCl3, 125
MHz) δ: 22.17, 22.52, 23.90, 24.74, 38.60, 54.66, 66.45,
77.30, 113.41, 127.06, 136.02, 158.59. HRMS calcd for
[C14H22O2Na]+ 245.1512, found 245.1502.
References
1
(a) Miles, W. H.; Connel, K. B. J. Chem. Educ. 2006, 83,
285.
General procedure for compounds 5a— 5e
(b) Pagliaro, M.; Ciriminna, R.; Kimura, H.; Rossi, M.;
Della Pina, C. Angew. Chem., Int. Ed. Engl. 2007, 46, 4434.
(c) Williamson, A. W. J. Chem. Soc. 1852, 4, 229.
(d) Bagget, N. In Comprehensive Organic Chemistry, Vol.
1, Eds.: Barton, D.; Ollis, W. D., Pergamon, Oxford, 1979,
p. 799.
(a) Smith, M. B.; March, J. In Advanced Organic Chemistry,
Wiley Interscience, New York, 2001, p. 479.
(b) Larock, R. C. In Comprehensive Organic Transforma-
tions, Wiley Interscience, New York, 1999, p. 897.
(c) Kim, S.; Chung, K. N.; Yang, S. J. Org. Chem. 1987, 52,
3917.
A mixture of diphenylmethanol 5a (184 mg, 1.0
mmol) and NaHSO3 (0.6 mg, 0.006 mmol) was stirred
at 150 ℃ in oil bath for 1 h. After the reaction finished,
the residue was purified by column chromatography on
silica gel to give the corresponding ether 5a in 90% iso-
lated yield.
2
Benzhydryloxydiphenylmethane (5a)
White
solid, m.p. 104—105 ℃ (Lit.5a 108—110 ℃), 90%
1
yield; H NMR (CDCl3, 400 MHz) δ: 5.40 (s, 2H),
7.23—7.37 (m,20H).
1-((4-Methoxyphenyl)((4-methoxyphenyl)(phen-
yl) methoxy)methyl)benzene (5b) White solid, m.p.
120—122 ℃ (Lit.16 122—123 ℃), 95% yield; 1H
NMR (CDCl3, 400 MHz) δ: 3.77 (s, 6H), 5.34 (s, 2H),
6.84 (d, J=7.8 Hz, 4H), 7.24—7.34 (m, 14H).
(d) Ooi, T.; Ichikawa, H.; Itagaki, Y.; Maruoka, K. Hetero-
cycles 2000, 52, 575.
(e) Mico, A. D.; Margarita, R.; Piancatelli, G. Tetrahedron
Lett. 1995, 36, 2679.
Chin. J. Chem. 2011, 29, 1180— 1184
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