ORGANIC
LETTERS
2006
Vol. 8, No. 12
2543-2545
Acceptor-Free Alcohol Dehydrogenation
by Recyclable Ruthenium Catalyst
Won-Hee Kim, In Soo Park, and Jaiwook Park*
Center for Integrated Molecular System, Department of Chemistry,
Pohang UniVersity of Science and Technology, San 31 Hyojadong, Pohang,
Kyeongbuk 790-784, Republic of Korea
Received March 28, 2006
ABSTRACT
An efficient oxidant-free oxidation for a wide range of alcohols was achieved by a recyclable ruthenium catalyst. The catalyst was prepared
from readily available reagents by a one-pot synthesis through nanoparticle generation and gelation.
Oxidation of alcohols to carbonyl compounds is a funda-
mental organic transformation.1 To meet environmental and
economical acceptability, much effort has been devoted to
develop catalysts systems using molecular oxygen and
hydrogen peroxide as the hydrogen acceptors.2 However,
their application to a large-scale production may be hindered
by safety problems.3 Although transfer dehydrogenation of
alcohols using ketones and alkenes in anaerobic conditions
can be an alternative method, acceptor-free alcohol dehy-
drogenation is ideal. Several homogeneous catalyst systems
have been reported for the dehydrogenation, but they suffer
from air sensitivity, low catalytic activity, harsh conditions,
requirement of additives, and/or difficult catalyst synthesis
and manipulation.4-8
Heterogeneous catalysts for the dehydrogenation, in
general, have been developed mainly for the interest of
hydrogen production from renewable biomass or its fermen-
tation products.4a Our group has developed several catalyst
systems for alcohol oxidation under aerobic and anaerobic
conditions.5,9b Palladium nanoparticles in aluminum oxyhy-
droxide is a recent example for the aerobic alcohol oxidation,
and an immobilized form of Shvo’s diruthenium complex is
for the anaerobic alcohol dehydrogenation without any
additives.
Here, we describe a recyclable and easily makeable
heterogeneous catalyst (1) for acceptor-free alcohol dehy-
drogenation (Scheme 1). It is active under mild conditions
without additives for a wide range of alcohols including those
having heteroatoms such as nitrogen and sulfur.
Recently, we have reported a simple synthetic method for
recyclable metal nanoparticle catalysts through a sol-gel
process,9 which involves readily available reagents and does
not require calcination nor sintering. The ruthenium catalyst
(1) (a) Sheldon, R. A.; Kochi, J. K. Metal-Catalyzed Oxidations of
Organic Compounds; Academic Press: New York, 1984. (b) Hudlicky, M.
Oxidation in Organic Chemistry; American Chemical Society: Washington,
DC, 1990.
(2) (a) Sheldon, R. A.; Arends, I. W. C. E.; Dijksman, A. Catal. Today
2000, 57, 157. (b) Muzart, J. Tetrahedron 2003, 59, 5789. (c) Zhan, B.-Z.;
Thompson, A. Tetrahedron 2004, 60, 2917. (d) Sheldon, R. A.; van Santen,
R. A. Catalytic Oxidations: Principles and Applications; World Scien-
tific: Singapore, 1995; p 239.
(3) (a) Keresszegi, C.; Mallat, T.; Baiker, A. New J. Chem. 2001, 25,
1163. (b) Zaccheria, F.; Ravasio, N.; Psaro, R.; Fusi, A. Chem. Commun.
2005, 253.
(4) (a) Junge, H.; Beller, M. Tetrahedron Lett. 2005, 46, 1031. (b) Meijer,
R. H.; Ligthart, G. B. W. L.; Meuldijk, J.; Vekemans, J. A. J. M.; Hulshof,
L. A. J. Mol. Catal. A 2004, 218, 29.
(6) van Buijtenen, J.; Meuldijk, J.; Vekemans, J. A. J. M.; Hulshof, L.
A.; Kooijman, H.; Spek, A. L. Organometallics 2006, 25, 873.
(7) Zhang, J.; Gandelman, M.; Shimon, L. J. W.; Rozenberg, H.; Milstein,
D. Organometallics 2004, 23, 4026.
(8) Adair, G. R. A.; Williams, J. M. J. Tetrahedron Lett. 2005, 46, 8233.
(9) (a) Kwon, M. S.; Kim, N.; Seo, S. H.; Park, I. S.; Cheedrala, R. K.;
Park, J. Angew. Chem., Int. Ed. 2005, 44, 6913. (b) Kwon, M. S.; Kim, N.;
Park, C. M.; Lee, J. S.; Kang, K. Y.; Park, J. Org. Lett. 2005, 7, 1077. (c)
Park, I. S.; Kwon, M. S.; Kim, N.; Lee, J. S.; Kang, K. Y.; Park, J. Chem.
Commun. 2005, 5667. (d) Kim, N.; Kwon, M. S.; Park, C. M.; Park, J.
Tetrahedron Lett. 2004, 45, 7057.
(5) Choi, J. H.; Kim, N.; Shin Y. J.; Park, J. H.; Park, J. Tetrahedron
Lett. 2004, 45, 4607.
10.1021/ol060750z CCC: $33.50
© 2006 American Chemical Society
Published on Web 05/11/2006