C. S. Cho et al. / Tetrahedron Letters 47 (2006) 6781–6785
6785
ketimine alcohol 7 initially formed from 1 and 2a, and
subsequent intramolecular aldol-type condensation of
Shim, S. C. Tetrahedron 2001, 57, 3321; (d) Cho, C. S.;
Kim, J. H.; Choi, H.-J.; Kim, T.-J.; Shim, S. C. Tetra-
hedron Lett. 2003, 44, 2975.
. For a review: Murahashi, S.-I. Angew. Chem., Int. Ed.
Engl. 1995, 34, 2443.
. (a) Cho, C. S. J. Organomet. Chem. 2005, 690, 4094; (b)
Cho, C. S.; Lee, N. Y.; Kim, T.-J.; Shim, S. C. J.
Heterocycl. Chem. 2004, 41, 409.
. Cho, C. S.; Kim, B. T.; Kim, T.-J.; Shim, S. C. Chem.
Commun. 2001, 2576.
8
. The reaction with aldehyde 4h for quinoline 3y also
5
6
similarly proceeds via an aldimine 9 formation followed
by the intramolecular aldol reaction.
In summary, we have shown that 2-aminobenzyl alcohol
can be oxidatively cyclized with ketones as well as alde-
hydes in the presence of a copper catalyst and a base to
afford quinolines in good yields. We believe that the
present reaction will work as a useful procedure for
transition metal-catalyzed modified Friedl a¨ nder quinol-
ine synthesis since it proceeds not only in the presence
of a cheap copper catalyst but also in the absence of a
hydrogen acceptor.
7
8. Cho, C. S.; Kim, B. T.; Choi, H.-J.; Kim, T.-J.; Shim, S. C.
Tetrahedron 2003, 59, 7997.
9
. For similar ruthenium- and iridium-catalyzed oxidative
cyclization of 2-aminobenzyl alcohol with ketones leading
to quinolines: (a) Motokura, K.; Mizugaki, T.; Ebitani,
K.; Kaneda, K. Tetrahedron Lett. 2004, 45, 6029; (b)
Mart ´ı nez, R.; Brand, G. J.; Ram o´ n, D. J.; Yus, M.
Tetrahedron Lett. 2005, 46, 3683; (c) Taguchi, K.; Saka-
guchi, S.; Ishii, Y. Tetrahedron Lett. 2005, 46, 4539.
0. It has recently been found that carbonyl compounds (or
secondary alcohols) are coupled with primary alcohols in
the presence of a ruthenium catalyst and a base: (a) Cho,
C. S.; Kim, B. T.; Kim, T.-J.; Shim, S. C. J. Org. Chem.
Acknowledgements
1
The present work was supported by the Korea Research
Foundation Grant funded by Korea Government
2
001, 66, 9020; (b) Cho, C. S.; Kim, B. T.; Kim, T.-J.;
(
2
MOEHRD, Basic Research Promotion Fund) (KRF-
005-015-C00264). C.S.C. gratefully acknowledges a
Shim, S. C. Tetrahedron Lett. 2002, 43, 7987; (c) Cho, C.
S.; Kim, B. T.; Kim, H.-S.; Kim, T.-J.; Shim, S. C.
Organometallics 2003, 22, 3608.
Research Professor Grant of Kyungpook National
University (2005).
1
1. (a) Friedl a¨ nder, P. Chem. Ber. 1882, 15, 2572; For a
review, see: (b) Cheng, C.-C.; Yan, S.-J. Org. React. 1982,
2
8, 37; For a regioselective Friedl a¨ nder quinoline synthe-
References and notes
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1
. (a) Jones, G. In Comprehensive Heterocyclic Chemistry;
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hedron: Asymmetry 1999, 10, 2045.
13. For ruthenium-catalyzed oxidative cyclization of 2-amino-
benzyl alcohol with aldehydes leading to 3-substituted
quinolines Cho, C. S.; Ren, W. X.; Shim, S. C. Bull.
Korean Chem. Soc. 2005, 26, 2038.
14. Hudlick y´ , M. Oxidation in Organic Chemistry; American
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15. We confirmed in a separate experiment that 1 was oxidized
2
3
. (a) Amii, H.; Kishikawa, Y.; Uneyama, K. Org. Lett.
2
001, 3, 1109, and references cited therein; (b) Cho, C. S.;
Oh, B. H.; Kim, J. S.; Kim, T.-J.; Shim, S. C. Chem.
Commun. 2000, 1885, and references cited therein.
. (a) Cho, C. S.; Oh, B. H.; Shim, S. C. Tetrahedron Lett.
1
999, 40, 1499; (b) Cho, C. S.; Oh, B. H.; Shim, S. C. J.
Heterocycl. Chem. 1999, 36, 1175; (c) Cho, C. S.; Kim, J.
S.; Oh, B. H.; Kim, T.-J.; Shim, S. C. Tetrahedron 2000,
5
6, 7747; (d) Cho, C. S.; Kim, T. K.; Kim, B. T.; Kim,
T.-J.; Shim, S. C. J. Organomet. Chem. 2002, 650, 65; (e)
Cho, C. S.; Lee, N. Y.; Kim, T.-J.; Shim, S. C.
J. Heterocycl. Chem. 2004, 41, 423.
. For our recent report on synthesis of indoles via similar
ruthenium-catalyzed alkanol group transfer from alkanol-
amines to N-atom of anilines: (a) Cho, C. S.; Lim, H. K.;
Shim, S. C.; Kim, T. J.; Choi, H.-J. Chem. Commun. 1998,
4
to 5 in 50% yield with 85% conversion of 1 under CuCl
2
/
O
2
/KOH catalytic system, however, benzyl alcohol was
9
95; (b) Cho, C. S.; Kim, J. H.; Shim, S. C. Tetrahedron
not effectively oxidized to benzaldehyde (11% yield) under
the same catalytic system.
Lett. 2000, 41, 1811; (c) Cho, C. S.; Kim, J. H.; Kim, T.-J.;