February 1998
SYNLETT
185
-1
1
undesired reactions. The use of simple tetraalkylamines (having ethyl
and higher alkyl groups) gave relatively better yields of ester. Too weak
bases such as pyridine do not work simply because the lack of ability to
absorb acid.
cm . H NMR (CDCl ) δ: 1.42 (3H, t, J=7.2 Hz, CH -CH -), 2.65 (3H,
3 3 2
s, CH CO), 4.41 (2H, q, J=7.2 Hz, CH -CH -), 8.01 and 8.13 (each 2H,
dt, J=8.8, 1.7 Hz). C NMR (CDCl ) δ: 14.17 (CH -CH -), 26.79
3
3
2
13
3
3
2
(CH CO), 61.38 (O-CH -), 128.13 and 129.74 (aromatic CH), 134.23
3
2
and 140.11 (aromatic C), 165.72 (ester C=O), 197.59 (ketone C=O).
In conclusion, palladium-catalyzed methoxy- and ethoxycarbonylation
of aryl tosylates successfully proceeded to give the corresponding
arylcarboxylates. When 4-position of aryl tosylate is substituted by an
electron withdrawing group in the case of ethoxycarbonylation, the
yield of ethyl ester considerably increased. Especially, the
ethoxycarbonylation of 4-acetylphenyl tosylate gave the corresponding
ethyl ester in high yield which is satisfactory for preparative purpose. It
can be said that this reaction is particularly applicable to acylphenyl
tosylates to give alkyl acylbenzoates. Methoxycarbonylation of aryl
tosylates occurred with some base-mediated side reactions.
References and Notes
(1) Yoneyama, M.; Kakimoto, M.; Imai, Y. Macromolecules 1989,
22, 2593.
(2) Sugi, Y.; Takeuchi, K.; Hanaoka, T.; Matsuzaki, T.; Takagi, S.;
Doi, Y. Sekiyu Gakkaishi 1994, 37, 70.
(3) Kubota, Y.; Hanaoka, T.; Takeuchi, K.; Sugi, Y. Synlett 1994,
515.
(4) Kubota, Y.; Hanaoka, T.; Takeuchi, K.; Sugi, Y. J. Chem. Soc.,
Chem. Commum. 1994, 1553.
Typical procedure:
(5) Kubota, Y.; Hanaoka, T.; Takeuchi, K.; Sugi, Y. J. Mol. Cat. A:
Chemical 1996, 111, L187.
Synthesis of 4-acetylphenyl tosylate (2a):
To a suspension of 4-acetylphenol (9.99 g, 73.4 mmol) in pyridine (70
ml), 16.8 g of TsCl (88.1 mmol) was added portionwise at room
temperature and the whole mixture was stirred at 45 °C for 14h. After
cooling to room temperature, 100 ml of water was added to the mixture
and stirred at room temperature for 3 h. This mixture was diluted with
benzene (1000 ml) and washed with water (500 ml), 10 % aqueous HCl
(6) Kubota, Y.; Takeuchi, K.; Hanaoka, T.; Sugi, Y. Bull. Chem. Soc.
Jpn. 1994, 67, 563.
(7) Kubota, Y.; Takeuchi, K.; Hanaoka, T.; Sugi, Y. Catal. Today
1996, 31, 27.
(8) Dolle, R. E.; Schmidt, S. J.; Kruse, L. I. J. Chem. Soc., Chem.
Commun. 1987, 904.
(500 ml x 3), water (500 ml x 2), saturated aqueous NaHCO (500 x 2),
3
and brine (500 ml x 2), and then dried over Na SO . After filtration,
solvent was evaporated in vacuo to give a white solid (20.9 g).
Recrystallization from benzene (20 ml)-hexane (40 ml) gave 4-
(9) Cacchi, S.; Ciattini, P. G.; Morera, E.; Ortar, G. Tetrahedron
Letters 1986, 27, 3931.
2
4
(10) Cassar, L.; Chiuoli, G. P.; Guerrieri, F. Synthesis 1973, 509.
(11) Heck, R. F. Adv. Catal. 1977, 26, 323.
acetylphenyl tosylate (2a) as colorless fine needles (17.7 g, 83 %). mp
-1
62.5-63.5 °C. IR (KBr): 1682, 1379 cm . Anal. Calcd for C
H O S:
15 14 4
1
(12) Moser, W. R.; Wang, A. W.; Kildahl, N. K. J. Am. Chem. Soc.
1988, 110, 2816.
C, 62.05; H, 4.86. Found: C, 62.02; H, 4.77. H NMR (CDCl ) δ: 2.46
3
(3H, s, Ar-CH ), 2.58 (3H, s, CH CO), 7.09 and 7.90 (each 2H, dt,
3
3
13
(13) Stille, J. K.; Wong,P. K. J. Org. Chem. 1975, 40, 532.
J=8.9, 2.4 Hz), 7.33 and 7.71 (each 2H, dt, J=8.3 Hz, 1.9 Hz). C NMR
(CDCl ) δ: 21.66 (CH -Ar), 26.55 (CH CO), 122.50, 128.47, 129.92
(14) Ben-David, Y.; Portnoy, M; Milstein, D. J. Am. Chem. Soc. 1989,
111, 8742.
3
3
3
and 130.04 (aromatic CH), 132.09, 135.68, 145.79 and 152.98 (aromatic
C), 196.69 (C=O).
(15) Adapa, S. R.; Prasad, C. S. N. J. Chem. Soc., Perkin Trans. I 1989,
1706.
Ethoxycarbonylation of 2a:
(16) McDaniel, D. H.; Brown, H. C. J. Org. Chem., 1958, 23, 420.
(17) Brown, H. C.; Okamoto, Y. J. Am. Chem. Soc., 1958, 80, 4979.
(18) Sugi, Y.; Bando, K. Chem. Lett. 1976, 727.
In a 50 ml stainless-steel autoclave were placed 725.9 mg (2.5 mmol) of
2a, 17.7 mg (0.1 mmol) of PdCl , 82.5 mg (0.2 mmol) of dppp, 388.3
2
mg (1.25 mmol) of n-docosane, 5 ml of ethanol, and 308.5 mg (2.75
mmol) of DABCO. Carbon monoxide was introduced at 10 bar of an
initial pressure and then heated with stirring at 150 °C in an oil bath for
3h. After excess carbon monoxide was purged, the reaction mixture was
diluted by chloroform. Ethyl 4-acetylbenzoate (4a) and unreacted 2a
were found in the mixture by a GC analysis. They were separated by
column chromatography on silica gel (eluent: hexane-ethyl acetate) to
give 355 mg (74 %) of 4a and 71 mg (11 %) of 2a. 4a was recrystallized
from hexane and obtained as colorless pillars. mp 55.5–56.5 Anal. Calcd
(19) Doughty, D. H.; Pignolet, L. H. J. Am. Chem. Soc. 1978, 100,
7083.
(20) Perry, R. J.; Wilson, B. D. Macromolecules 1993, 26, 1503 and
references cited therein.
Smith, R. M.; Martell, A. E. Critical Stability Constants; Plenum
Press: New York, 1975; Vol. 2.
House, H. O. Modern Synthetic Reactions; W. A. Benjamin, Inc.:
California, 1972; Capter 9 and references cited therein.
Hall, H. K., Jr. J. Am. Soc. Chem. 1957, 79, 5441.
Kobayashi, T.; Abe, F.; Tanaka, M. J. Mol. Cat. 1988, 45, 91.
for C
H
O : C, 68.74; H, 6.29. Found: C, 68.88; H, 6.34. MS m/z:
11 12
3
+
+
+
192 (M ), 177 (M – CH ), 147 (M –OCH CH ). IR (KBr): 1717, 1684
3
2
3