Lewis Acids as Catalysts for the Decarboxylative Esterification of Carboxylic Acids
COMMUNICATIONS
67.0, 21.0; MS (EI): m/z (%) 270 (28) [M ], 228 (46), 210 (25),
References and Notes
183 (7), 121 (100), 91 (61), 43 (22); HRMS (EI): calcd. for
C16H14O4 [M ]: 270.08921; found 270.08931; anal. calcd. for
C16H14O4: C 71.10, H 5.22, O 23.68%; found: C 70.85, H 5.30, O
23.48%.
[1] T. W. Greene, P. G. M. Wuts, Protective Groups in
Organic Synthesis, Wiley, New York, 3rd ed., 1999,
pp. 369 427.
[2] For particularly efficient methods, see: a) J. Otera,
Angew. Chem. 2001, 113, 2099 2100; Angew. Chem.
Int. Ed. 2001, 40, 2044 2045; b) K. Ishihara, S. Ohara, H.
Yamamoto, Science 2000, 290, 1140 1142; c) J. N. Xiang,
A. Orita, J. Otera, Angew. Chem. 2002, 114, 4291 4293;
Angew. Chem. Int. Ed. 2002, 41, 4117 4119; d) K.
Wakasugi, T. Misaki, K. Yamada, Y. Tanabe, Tetrahedron
Lett. 2000, 41, 5249 5252; e) G. A. Olah, G. Liang, J.
Staral, J. Am. Chem. Soc. 1974, 96, 8113 8115.
Synthesis of 3-Acetoxybenzoic Acid t-Butyl Ester (4c)
An oven-dried flask was charged with 3-acetoxybenzoic acid
1b (180 mg, 1.00 mmol), di-t-butyl dicarbonate 2b (450 mg,
2.00 mmol), and magnesium perchlorate (2.20 mg, 0.01 mmol).
Dry nitromethane (4 mL) was added by a syringe and the
mixture was stirred at 408C overnight. After the reaction was
complete (TLC), ethyl acetate was added and the organic layer
was washed consecutively with aqueous ammonium chloride
and sodium bicarbonate solution, water and brine. Afterdrying
with magnesium sulfate and removal of the volatiles under
vacuum, the product was obtained in high purity. For spectro-
scopic characterization, the product was filtered through a
small plug of silica using hexane/dichloromethane (5:5) as
eluent. After removal of the volatiles, 4c was obtained as a
colorless liquid; yield: 226 mg (96%). 1H NMR (300 MHz,
CDCl3): d 7.88 7.85 (d, 1H), 7.68 (s, 1H), 7.45 7.39 (t, 1H),
7.27 7.23 (d, 1H), 2.31 (s, 3H), 1.59 (s, 9H); 13C NMR
(75 MHz, CDCl3): d 169.3, 164.7, 150.5, 133.6, 129.2, 127.9,
¬
[3] a) A. K. Chakraborti, A. Basak (nee Nandi), V. Grover,
J. Org. Chem. 1999, 64, 8014 8017; b) A. Merz, Angew.
Chem. 1973, 85, 868 869; Angew. Chem. Int. Ed. 1973,
12, 846 857.
[4] For examples, see a) R. A. W. Johnstone, M. E. Rose,
Tetrahedron 1979, 35, 2169 2173; b) P. Chevallet, P.
Garrouste, B. Malawska, J. Martinez, Tetrahedron Lett.
1993, 34, 7409 7412; c) T. Wang, A. S. Lui, I. S. Clouds-
dale, Org. Lett. 1999, 1, 1835 1837.
œ
[5] W.-C. Shieh, S. Dell, O. Repic, J. Org. Chem. 2002, 67,
2188 2191.
126.9, 122.6, 81.4, 28.4, 21.1; MS (EI): m/z (%) 236 (2) [M ],
[6] a) B. Neises, W. Steglich, Angew. Chem. 1978, 90, 556
557; Angew. Chem. Int. Ed. 1978, 17, 522 523; b) A.
Hassner, V. Alexanian, Tetrahedron Lett. 1978, 4475
4478.
194 (24), 138 (100), 121 (20), 57 (38), 43 (24), 41 (26); HRMS
(EI): calcd. for C13H16O4 [M ]: 236.10486; found 236.10500;
anal. calcd. for C13H16O4: C 66.09, H 6.83, O 27.09%; found: C
65.87, H 6.78, O 27.26%.
[7] O. Mitsunobu, Synthesis 1981, 1 28.
The reactions in Table 2 were performed following the
above procedure. All products were isolated and characterized
by means of 1H and 13C NMR as well as by GC-MS and HRMS.
The analytical data was identical with those reported in the
literature.
[8] K. Takeda, A. Akiyama, H. Nakamura, S. Takizawa, Y.
Mizuno, H. Takayanagi, Y. Harigaya, Synthesis 1994,
1063 1066.
[9] a) L. J. Goo˚en, L. Winkel, A. Dˆhring, K. Ghosh, J.
Paetzold, Synlett 2002, 1237 1240; b) L. J. Goo˚en, J.
Paetzold, L. Winkel, Synlett 2002, 1721 1723.
[10] See e. g. Aldrich catalog of laboratory chemicals, 2003.
[11] Other magnesium salts with non-coordinating anions,
e. g., Mg(OTf)2, gave similar results.
[12] For the activation of acetic anhydride with Mg(ClO4)2,
see: G. Bartoli, M. Bosco, R. Dalpozzo, E. Marcantoni,
M. Massaccesi, S. Rinaldi, L. Sambri, Synlett 2003, 35
38.
Acknowledgements
We thank D. Neis for technical assistance and Prof. Dr. M. T.
Reetz for generous support and constant encouragement and
gratefully acknowledge the financial support of the DFG, the
FCI, and the BMBF.
Adv. Synth. Catal. 2003, 345, 943 947
asc.wiley-vch.de
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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