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A. Perosa et al.
LETTER
(20) A general procedure for the O-alkylation of phenol using the
asymmetric organic carbonates 3a-3g is as follows: a 25 mL
flask, fitted with a reflux condenser, a rubber septum, a
thermometer, and a nitrogen inlet, was charged with phenol
(0.30 g, 3.2 mmol), K2CO3 (0.6 g, 4.5 mmol), the organic
carbonate (2.8 g, 16 mmol), DMF (30 mL), and n-tetradecane
as the internal standard (0.07 mmol). The mixture was stirred
under N2 at the chosen temperature (120, 130, 140, 150 °C)
until complete phenol conversion was observed, as monitored
by GLC. All reactions were repeated twice to assure
reproducibility. Both phenol conversion and anisole yield
were determined by comparison to the internal standard.
Reactions were also run using different volumes of DMF (2,
4, 6, 8, and 10 mL) or 3e as the solvent (5.7 g, 32 mmol).
(21) A. Streitwieser Chem. Rev. 1956, 56, 571.
(22) M. Charton J. Am. Chem. Soc. 1975, 97, 3694.
(23) G. Caldwell, T. F. Magnera, P. Kebarle J. Am. Chem. Soc.
1984, 106, 959.
(24) J. F. King, G. T. Y. Tsang, M. M. Abdel-Malik, N. C. Payne
J. Am. Chem. Soc 1985, 107, 3224.
(25) P. Tundo, G. Moraglio, F. Trotta Ind. Eng. Chem. Res. 1989,
28, 881.
(26) M. L Wang, K. R. Chang Ind. Eng. Chem. Res. 1991, 30,
2378.
(27) Since anisole boils at 154 °C, reactions were followed by
monitoring the phenol concentration. Once the reaction
mixture was cooled at room temperature, the mass balance
between phenol and anisole was determined by GC.
(28) Procedure for the O-alkylation of different phenols using the
organic carbonate 3e and triglyme as solvent (Table 2): a
mixture of the appropriate phenol (2-5 g, see Table 2 for
amounts), K2CO3, and carbonate 3e, in a 1: 1.1: 5 molar ratio,
was dissolved in 50 mL of triglyme and heated at 140 °C
under N2, until complete substrate conversion. After cooling,
150 mL of diethyl ether were added, and the solution was
washed with water (5 x 50 mL). The organic phase was dried
over Na2SO4, filtered, and the solvent was removed under
reduced pressure. The product was either distilled under
reduced pressure (anisole, yield 81%; p-methyl anisole, 79%;
p-chloroanisole, 60%); or flash-chromatographed on a column
of silica gel (2-methoxynaphthalene, 83%; o- and p-
acetylanisole, 81% combined), eluting with a 1 to 1 mixture of
ethyl ether and petroleum ether. All products were identified
by comparing spectroscopic data with those of authentic
samples. The 45 to 55 mixture of o- and p-acetylphenol used
in the above procedure was prepared by a Friedel-Crafts
acylation of phenol with acetyl chloride, followed by a Fries
rearrangement.29
Acknowledgement
CNR (Italian National Research Council, contract no.
98.000571.PF37) and INCA (Interuniversity Consortium Chemi-
stry for the Environment) are gratefully acknowledged for the finan-
cial support.
References and Notes
(1) F. Trotta, P. Tundo, G. Moraglio J. Org. Chem. 1987, 52,
1300.
(2) P. Tundo, F. Trotta, G. Moraglio J. Chem. Soc., Perkin Trans.
1 1989, 1070.
(3) M. Lissel, S. Schmidt, B. Neumann Synthesis 1986, 382.
(4) P. Tundo In Continuous-Flow Methods in Organic Synthesis,
E. Horwood, Ed; Chichester, 1991.
(5) Y. Ono Pure Appl. Chem. 1996, 68, 367.
(6) (a) F. Rivetti, U. Romano, D. Delledonne, In Green
Chemistry: Designing Chemistry for the Environment, P.
Anastas, T. Williamson, Eds., ACS Symposium Series No.
626, 1996, Chap. 6, pp. 70-80; (b) M. Selva, P. Tundo, C. A.
Marques, In Green Chemistry: Designing Chemistry for the
Environment, P. Anastas, T. Williamson, Eds., ACS
Symposium Series No. 626, 1996, Chap. 5, pp. 81-91.
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1995, 488, c15.
(8) P. Tundo, M. Selva Chemtech 1995, 25, 31.
(9) A. Bomben, M. Selva, P. Tundo, L. Valli, Ind. Eng. Chem.
Res. 1999, 38, 2075.
(10) M. Selva, C. A. Marques, P. Tundo J. Chem. Soc., Perkin
Trans. 1 1994, 1323.
(11) A. Bomben, C. A. Marques, M. Selva, P. Tundo Tetrahedron
1995, 51, 11573.
(12) A. Bomben, M. Selva, P. Tundo J. Chem. Res. 1997, 448.
(13) P. Tundo, M. Selva, A. Bomben Org. Synth. 1998, 76, 169-
177.
(14) M. Selva, A. Bomben, P. Tundo J. Chem. Soc., Perkin Trans.
1 1997, 1041.
(15) M. Lissel, A. R. Rohani-Dezfuli, G. Vogt J. Chem. Res. (M)
1989, 2434.
(16) Y. Lee, I. Shimizu Synlett 1998, 1063.
(17) M. Selva, F. Trotta, P. Tundo J. Chem. Soc., Perkin Trans.
1992, 519.
(18) (a) M. Matner, R. P. Kurkjy, R. J. Cotter Chem. Rev. 1964, 64,
645; (b) H. Badad, A. G. Zeiler Chem. Rev. 1973, 73, 80.
(19) 2-(2-Methoxyethoxy)ethyl methyl carbonate 3e: 1H NMR
(CDCl3): d ppm 4.13 (m, 2H), 3.65 (s, 3H), 3.55 (m, 2H), 3.47
(m, 2H), 3.19 (s, 3H); Mass spectrum (70 eV): m/z (%): 178
(M+, < 1), 103 ([M - CH3 OCH2CH2O]+, 10), 59 ([M -
CH3 OCH2CH2 OCH2CH2O]+, 100), 58 (58). Bp = 48-50 °C/
0.1.
(29) E. Miller, W. H. Hartung, Org. Synth. Coll. Vol. 2, Wiley
Chichester, 1961; p. 543
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Synlett 2000, No. 2, 272–274 ISSN 0936-5214 © Thieme Stuttgart · New York