Nafion-H catalysed intramolecular Friedel-Crafts acylation: Formation of cyclic ketones and related heterocycles

Article abstract of DOI:10.1055/s-1999-2770

Benzoic acids with suitable substituents bearing phenyl ring in the ortho position undergo cyclization by intramolecular Friedel-Crafts acylation in the presence of Nafion-H, a perfluorinated resinsulfonic acid catalyst. Synthesis of anthraquinone, anthrone, fluorenone, α-tetralone, 1-benzosurberone and heterocycles such as acridone, xanthone etc. is easily achieved in good to excellent yields (82-95%) by this method.

Full text of DOI:10.1055/s-1999-2770

LETTER
1067
Nafion-H Catalysed Intramolecular Friedel-Crafts Acylation: Formation of
Cyclic Ketones and Related Heterocycles1
George A. Olah,* Thomas Mathew, Morteza Farnia, G. K. Surya Prakash*
Katherine B. and Donald P. Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California,
Los Angeles, CA 90089-166, USA
Fax +1 (213) 7406679; E-mail: olah@methyl.usc.edu
Received 12 February 1999
H were studied,9,10 intramolecular acylation was not ob-
Abstract: Benzoic acids with suitable substituents bearing phenyl
served. The intramolecular acylation reactions were car-
ring in the ortho position undergo cyclization by intramolecular
ried out by heating a stirred mixture of the corresponding
Friedel-Crafts acylation in the presence of Nafion-H, a perfluorinat-
ed resinsulfonic acid catalyst. Synthesis of anthraquinone, anthrone,
carboxylic acid derivative (4a-g) and the solid Nafion-H
fluorenone, a-tetralone, 1-benzosuberone and heterocycles such as as catalyst at about 180 °C. Products (5a-g) were simply
acridone, xanthone etc. is easily achieved in good to excellent yields
(82-95%) by this method.
isolated by filtering the hot reaction mixture and distilling
off the solvent. The reactions are generally fast and clean.
Key words: Nafion-H, Friedel-Crafts acylation, cylic ketones, het-
erocycles, dichlorobenzene
X
X
Nafion-H
(2)
Dichlorobenzene
C OH
O
C
O
We have shown in our previous reports that Nafion-H (1)
is a convenient catalyst for acid catalysed organic synthet-
ic transformations1-6 mainly due to its ease of separation
from the reaction mixture, high catalytic activity and high
selectivity. Nafion-H catalysed ring closure of 2,2’-diami-
no and 2,2’-dihydroxy biphenyls (2) to the corresponding
dibenzocarbazoles and furans (3)7,8 have also been studied
in detail (eq.1). Ring closure reactions of carboxylic acids
to ketones performed with various acid systems require el-
evated temperatures, long reaction times and use of excess
catalyst. Moreover, some of these reactions are associated
with undesirable side reactions during cyclizations.
4a-g
5a-g
X = -NH-, -O-, -CO-, -CH2-,
-CH2-CH2- etc.
82-95%
Equation 2
When the reaction was carried out in low boiling solvents
such as CH2Cl2, CCl4 etc., no reaction occurred. But the
reactions in solvents such as toluene, xylene, 4-t-butyltol-
uene proceeded with the formation of mixtures due to in-
termolecular condensation and other side reactions. Both
1,2- and 1,3-dichlorobenzenes are suitably deactivated,
high boiling solvents and their use lead to excellent con-
versions without any accompanying side reactions.11,12
(CF2
CF2)m
CF2 CF
O
(CF2 CF O)n CF2 CF2 SO3H
CF3
As shown in table 1, the present method provides excel-
lent yields of 5a-g with no other side products. The
amount of catalyst used relative to the substrate was 30-
35% by weight. The reactions were complete in 1-3 hrs.
The present procedure offers wide advantages over the
previously reported acylation methods. Reactions with al-
iphatic-type carbxylic acids 6a-c also gave the cyclized
products as expected. Eventhough the yield of 1-indanone
(7a) from 3-phenylpropionic acid was very low (ª5%), 4-
phenylbutyric acid (6b) and 5-phenylvaleric acid (6c) af-
forded high yields of a-tertalone (7b, 90%) and 1-benzo-
suberone (7c, 83%), respectively, in 1-2 hrs.
1
Figure 1
Nafion-H
Y
X
X
3
2
X = -NH2, -OH
Y = -NH-, -O-
Equation 1
COOH
(CH2)n
Nafion-H
These difficulties have prompted us to investigate the
scope and selectivity of Nafion-H as a catalyst for the
preparation of fluorenone and related cyclic ketones and
heterocycles from the corresponding biphenyl-2-carboxy-
lic acids or the appropriate benzoic acid derivatives under
relatively mild conditions. Although intermolecular
(CH2)n
Dichlorobenzene
O
6a-c
a-c, n = 2-4
7a-c
Friedel-Crafts acylation as well as alkylation over Nafion- Equation 3
Synlett 1999, No. 07, 1067–1068 ISSN 0936-5214 © Thieme Stuttgart · New York

1068
G. A. Olah et al.
LETTER
General Procedure for the Intramolecular Friedel-
Crafts Acylation:
A mixture of of 2-benzoyl benzoic acid 4a (1.130 g, 0.5
mMol) and Nafion-H (400 mg, 35 wt%) in 1,3-dichlo-
robenzene (30 mL) was refluxed for 3 hrs. The completion
of the reaction was monitered by GC/MS analysis. The
solid resin sulphonic acid was filtered off while the solu-
tion was hot and the filtrate was evaporated under vac-
cum. The residue was recrystallized from CH2Cl2 to get
light yellow crystals (940 mg, 90%) of anthraquinone
(5a), mp 284-286 °C.
Acknowledgement
The support of our work by Loker hydrocarbon Research Institute
is gratefully acknowledged.
References and Notes
(1) Considered as Catalysis by Solid Superacids, Part 33. For part
32, See Prakash, G. K. S.; Mathew, T.; Krishnaraj, S.;
Marinez, E. R.; Olah, G. A. Applied Catalysis, A: General
1999, in press
(2) Olah, G. A.; Arvanaghi, M.; Krishnamurthy, V. V. J. Org.
Chem. 1983, 48, 3359.
(3) Olah, G. A.; Iyer, P. S.; Prakash, G. K. S. Synthesis 1986, 513
and references there in.
(4) Wang, Q.; Li, X. Y.; Prakash G. K. S. Synlett 1990, 487; Olah,
G. A.; Torok, G.; Shamma, T.; Torok, M.; Prakash, G. K. S.
Catalysis Lett. 1996, 42, 5; Olah, G. A.; Shamma, T.; Prakash,
G. K. S. Catalysis Lett. 1997, 46, 1.
(5) Prakash, G. K. S.; Olah, G. A. In Procedings of the
International Symposium on Acid Base Catalysis; Tanabe, K.;
Hattori, H.; Yagamuchi, T.; Tanaka, T., Ed.; Kodansha Ltd.
Tokyo, 1988; p 60.
(6) Hachoumy, M.; Mathew, T.; Tongo, E. C.; Vankar, Y. D.;
Prakash, G. K. S.; Olah, G. A. Synlett 1999, 363.
(7) Yamato, T.; Hideshima, C.; Prakash, G. K. S.; Olah, G. A. J.
Org. Chem. 1991, 56, 3192.
(8) Yamoto, T.; Hideshima, C.; Prakash, G. K. S.; Olah, G. A. J.
Org. Chem. 1991, 56, 6248.
(9) Olah, G. A.; Malhotra, R.; Narang, S. C.; Olah, J. A. Synthesis
1978, 9, 672.
The Nafion-H catalyst was prepared from commercial
Nafion-K resin (from DuPont) as previously described.3
All melting points were uncorrected. GC/MS data of the
products were obtained on a Hewlett Packard 5890 series
spectrometer. NMR spectra were recorded with a Varian
Unity 300 (300 MHz) NMR spectrometer in CDCl3 or
DMSO-d6 using TMS as internal standard. The structure
of the products were confirmed by comparing the spectral
data with those of the authentic samples.
(10) Olah, G. A.; Mediar, D. Nouv. J. De. Chem. 1979, 3, 269.
(11) Mathew, T.; Keller, M.; Hunkler, D.; Prinzbach, H. Tet. Lett.
1996, 37, 4491.
(12) Bakkeren, F. J. A. D.; Schroer, F.; Klunder, A. J. H.;
Zwannenburg, B. Tet. Lett. 1998, 39, 9531.
Article Identifier:
1437-2096,E;1999,0,07,1067,1068,ftx,en;S00999ST.pdf
Synlett 1999, No. 07, 1067–1068 ISSN 0936-5214 © Thieme Stuttgart · New York