GaCl3-catalyzed arylation of cycloalkanes

Full text of DOI:10.1021/ja0164172

11310
J. Am. Chem. Soc. 2001, 123, 11310-11311
GaCl3-Catalyzed Arylation of Cycloalkanes
3
Table 1. GaCl Catalyzed Arylation of Cycloalkanes
Fumi Yonehara, Yoshiyuki Kido, Satoshi Morita, and
Masahiko Yamaguchi*
Department of Organic Chemistry
Graduate School of Pharmaceutical Sciences
Tohoku UniVersity, Aoba, Sendai 980-8578, Japan
ReceiVed June 14, 2001
ReVised Manuscript ReceiVed September 12, 2001
The alkylation of aromatic compounds is generally conducted
1
using alkenes or alkyl halides in the presence of a Lewis acid or
2
a transition-metal complex as the catalyst. The alkylation of
arenes with alkanes, which converts an aliphatic C-H bond to a
C-Ar bond, is more convenient, if it can be conducted effectively.
Such reactions in the presence of sacrificing reagents such as
3
organohalogen compounds or alkenes have been reported.
Aromatic alkylation, which proceeds via the C-C bond cleavage
4
of alkane, is known as destructive alkylation. Although a few
examples of the direct arylation of the alkane C-H bond, which
do not use the sacrificing reagents, have appeared,5 the
efficiency of the reaction is low; stoichiometric amounts of the
Lewis acid promoter are employed. During our studies on the
development of new aromatic C-C bond-formation reactions
-9
10
using GaCl
3
,
we found that the gallium compound catalyzes
the direct arylation of cycloalkanes.
Naphthalene is heated at 70 °C with GaCl (5 mol %) in excess
3
bicyclo[4.4.0]decane (a 1:1 mixture of cis- and trans-decahy-
dronaphthalene) for 40 h. After aqueous workup, the crude product
is heated by refluxing in 1-methylnaphthalene in the presence of
Pd/C to dehydrogenate the small amounts of 1,2,3,4-tetrahy-
dronaphthalenes formed: For example, ca. 170% (based on GaCl
of tetrahydronaphthalene is detected in the crude product.
-(Decahydronaphthalen-3-yl)naphthalenes (590% yield based on
GaCl ) and bis(decahydronaphthalen-3-yl)naphthalenes (237%
based on GaCl ) are obtained. It should be noted that the turnover
number “TON” of the reaction based on GaCl is 10.6, if that of
3
)
2
3
3
3
dialkylation is calculated to be 2. Some of the hydrogen that is
formed from the arene and the cycloalkane may be incorporated
in the tetrahydronaphthalene. The structure of the monoalkylated
(
1) (a) Olah, G. A. Friedel-Crafts Chemistry; John Wiley & Sons: New
York, 1973. (b) Taylor, R. Electrophilic Aromatic Substitution; John Wiley
Sons: New York, 1990.
2) Recent examples: (a) Matsumoto, T.; Taube, D. J.; Periana, R. A.;
&
(
Taube, H.; Yoshida, H. J. Am. Chem. Soc. 2000, 122, 7414-7415. (b)
Nishiyama, Y.; Kakushou, F.; Sonoda, N. Bull. Chem. Soc. Jpn. 2000, 73,
2
779-2782. (c) Singh, R. P.; Kamble, R. M.; Chandra, K. L.; Saravanan, P.;
Singh, V. K. Tetrahedron 2001, 57, 241-247.
3) (a) Schmerling, L.; Welch, R. W.; West, J. P. J. Am. Chem. Soc. 1956,
8, 5406-5409. (b) Schmerling, L.; Welch, R. W.; Luvisi, J. P. J. Am. Chem.
Soc. 1957, 79, 2636-2642 and references therein.
4) (a) Grosse, A. V.; Ipatieff, V. N. J. Am. Chem. Soc. 1935, 57, 2415-
419. (b) Grosse, A. V.; Ipatieff, V. N. J. Org. Chem. 1937, 2, 447-458. (c)
(
7
(
2
Grosse, A. V.; Mavity, J. M.; Ipatieff, V. N. J. Org. Chem. 1938, 3, 137-
1
45. (d) Sugahara, Y.; Hayami, J.; Sera, A.; Goto, R. Bull. Chem. Soc. Jpn.
969, 42, 2656-2662.
1
a
The structure of the major isomer is shown. b The yield is based
(
5) (a) Miethchen, R.; Kr o¨ ger, C.-F., Z. Chem. 1975, 135-141. (b)
on GaCl . Shown in parentheses are yields based on aromatic
3
Miethchen, R.; Steege, S.; Kr o¨ ger, C.-F. J. Prakt. Chem. 1983, 325, 823-
34 and references therein.
6) Olah, G. A.; Schilling, P.; Staral, J. S.; Halpern, Y.; Olah. J. A. J. Am.
compounds. cis-Cycloalkane was used. d trans-Cycloalkane was used.
c
8
e
(
The reaction was carried out with irradiation using a high-pressure
f
Chem. Soc. 1975, 97, 6807-6810.
mercury lamp (400 W). Isomer ratio regarding the methyl position of
(
7) Schmerling, L.; Vesely, J. A. J. Org. Chem. 1973, 38, 312-315.
cycloalkane. g Isomer ratio regarding the methyl position of the
(
8) Chalais, S.; Corn e´ lis, A.; Gerstmans, A.; Kolodziejski, W.; Laszlo, P.;
dehydrogenated compound.
Mathy, A.; M e´ tra, P. HelV. Chim. Acta. 1985, 68, 1196-1203.
9) Koltunov, K. Y.; Subbotina, E. N.; Repinskaya, I. B. Russ. J. Org.
Chem. 1997, 33, 689-693.
10) (a) Yamaguchi, M.; Kido, Y.; Hayashi, A.; Hirama, M. Angew. Chem.,
Int. Ed. Engl. 1997, 36, 1313-1315. (b) Kido, Y.; Yamaguchi, M. J. Org.
Chem. 1998, 63, 8086-8087. (c) Kido, Y.; Yoshimura, S.; Yamaguchi, M.;
Uchimaru, T. Bull. Chem. Soc. Jpn. 1999, 72, 1445-1458. (d) Yonehara, F.;
Kido, Y.; Yamaguchi, M. Chem. Commun. 2000, 1189-1190. (f) Kido, Y.;
Yonehara, F.; Yamaguchi, M. Tetrahedron 2001, 57, 827-833.
(
product, being a 1:2.4 mixture of two major isomers by GC, is
confirmed by elemental analysis. Treatment of the monoalkylated
products with excess dichlorodicyanoquinone (DDQ) by refluxing
in toluene for 0.5 h gives 2,2′-binaphthalene as a single product,
which indicates that C-C bond formation occurs at the 2-position
of naphthalene and at the 3-position of decahydronaphthalene.
(
1
0.1021/ja0164172 CCC: $20.00 © 2001 American Chemical Society
Published on Web 10/17/2001

Communications to the Editor
J. Am. Chem. Soc., Vol. 123, No. 45, 2001 11311
The coupling constants (J ) 10 Hz) of the benzylic protons show
the equatorial configuration of the naphthyl group. The cis-
stereochemistry of the decahydronaphthalene moiety is determined
by comparison with an authentic trans-compound. Notably, when
cis-decahydronaphthalene is used, the monoalkylated product is
obtained in 819% yield as a 1:2.4 mixture of two isomers and
the dialkylated product in 282% yield. In contrast, the trans-
isomer gives the alkylated arene only in 7% yield. The cis-
decahydronaphthalene was found to be the reactive species in
this C-C bond-formation reaction.
Scheme 1
Scheme 2
11
Arylation of decahydronaphthalene is conducted using meth-
ylnaphthalenes, phenanthrene, and m-xylene (Table 1). The
structures of the products are determined unambiguously by
converting them to partially dehydrogenated compounds of single
isomers with DDQ. Several authentic samples are prepared by
the coupling reaction of 2-bromonaphthalene and arylmagnesium
reagents. In all cases, decahydronaphthalene reacts at the 3-posi-
tion exclusively, and the arenes react at the least hindered
positions: 1-Methylnaphthalene reacts at the 3-position predomi-
nantly; 1,2-dimethylnaphthalene at the 6- and 7-positions; phenan-
threne at the 2- and 3-positions; and m-xylene at the 5-position.
Monoalkylated products are obtained in more than 400% yield
for the bicyclic and tricyclic arenes, while a trace amount of the
product is obtained with m-xylene. Irradiation with UV light
improves the yield of the 1,3-dimethylphenylation to 26% (based
hexane and naphthalene. The cis-isomer gives the monoalkylated
naphthalene in 560% yield and the dialkylated product in 117%,
while from the trans-isomer the former compound is obtained
only in 37% yield.
Contamination of a small amount of cycloalkene in the
cycloalkane can be excluded, since the hydrocarbon washed with
concentrated sulfuric acid also undergoes the same reaction. The
requirement of the tertiary C-H bond in the cycloalkane may be
explained by the initial activation of the reactive C-H bonds with
GaCl
3
to generate the tertiary cations. It appears that the tertiary
rather than
equatorial protons are preferentially activated by GaCl
3
on GaCl
gives three isomers at the 2-, 3-, and 4-positions in a ratio of
3
). Arylation of methylcyclohexane with naphthalene
the axial ones (Scheme 1). The formation of the thermodynami-
cally stable alkylated products may be due to the migration of
the cycloalkyl group on the aromatic ring under the given reaction
conditions. Accordingly, the treatment of 1-(1-methylcyclohexyl)-
1
1
:5:4, respectively. H NMR indicates that the naphthyl group
(benzylic H, J ) ca. 10 Hz), and probably also the methyl group,
occupies the equatorial position. 1,2-Dimethylcyclohexane gives
predominantly the 3,4-dimethyl derivative, and 1,3-dimethylcy-
clohexane, the 3,5-dimethyl derivative. No product derived from
the reaction at the tertiary carbon atom is detected. The TONs
are higher in the reactions of decahydronaphthalene and 1,2-
dimethylcyclohexane than those in methylcyclohexane and 1,3-
dimethylcyclohexane. The reaction of cyclohexane and naphtha-
lene gives a very low yield of the naphthylcyclohexane. The
importance of the adjacent tertiary carbons with the cis-config-
uration is confirmed again in the reaction of 1,2-dimethylcyclo-
naphthalene with a catalytic amount of GaCl
cyclohexane for 40 h at 70 °C gives 2-(methylcyclohexyl)-
naphthalenes in 50% yield based on GaCl as a mixture of three
3
(40 mol %) in
3
isomers in a 1:3:2 ratio (Scheme 2). The products are identical
to those obtained from methylcyclohexane and naphthalene.
To summarize, arylation of cycloalkanes with aromatic hydro-
3
carbons occurs in the presence of GaCl . This is a novel catalytic
reaction that forms a C-C bond between aromatic hydrocarbons
and aliphatic hydrocarbons without having to use a sacrificing
reagent.
(
11) Under an argon atmosphere, a solution of GaCl
3
(1.0 M in
cis-decahydronaphthalene, 0.25 mL) was added to a solution of naphthalene
Acknowledgment. This work was supported by grants from the Japan
Society of Promotion of Science. A fellowship to Y.K. from the Japan
Society of Promotion of Science for young Japanese scientists is gratefully
acknowledged.
(
640 mg, 5 mmol) in cis-decahydronaphthalene (1.25 mL). This mixture was
heated to 70 °C and stirred for 40 h at that temperature. After the reaction
was quenched by the addition of water, the organic layer was separated, washed
4
with saturated aqueous NH Cl and water, and dried over MgSO4. Solvents
were removed in vacuo, and the residue was treated with Pd/C (5%, 530 mg)
in refluxing 1-methylnaphthalene (0.7 mL) for 4 h. The mixture was diluted
with ether, and filtered by passing through Celite. The solvents were removed
in vacuo, and the residue was purified by flash column chromatography (silica
Supporting Information Available: Experimental procedures and
spectral data for all the products are provided (PDF). This material is
available free of charge via the Internet at http://pubs.acs.org.
gel, hexane) and GPC (CHCl
19% based on GaCl ) and the dialkylated product (283 mg, 282% based on
GaCl ).
3
) to give the monoalkylated product (541 mg,
8
3
3
JA0164172