A. Izumi et al. / Tetrahedron Letters 47 (2006) 9199–9201
9201
LnIr
The conversions and yields of products were estimated
from the peak areas based on the internal standard tech-
H
2
O
3a
12
3a
13
R
OH
O
nique using GLC. The products 2a–b, 2c, 2d, 2e,
1
14
15
3a
16
2
f, 2g, 2h–k, and 2l were reported previously.
1/2O2
Acknowledgements
R
H
LnIrH
2
R
OH
O
1
This work was supported by ‘High-Tech Research
Center’ Project for Private Universities: matching fund
subsidy from the Ministry of Education, Culture,
Sports, Science and Technology, 2005–2009.
R
O
2
R
OH
LnIr
R
O
R
References and notes
Scheme 1. A possible reaction pathway for the Ir-catalyzed reaction of
to 2.
1
2
3
. Tamura, Y.; Yamada, Y.; Inoue, K.; Yamamoto, Y.;
Yoshida, Z. J. Org. Chem. 1983, 48, 1286.
. Blum, Y.; Reshef, D.; Shvo, Y. Tetrahedron Lett. 1981, 22,
1
1
541.
genation of hemiacetals derived from alcohols and the
aldehydes by the action of the Ir-complex affords esters
. (a) Murahashi, S.-I.; Naota, T.; Ito, K.; Maeda, Y.; Taki,
H. J. Org. Chem. 1987, 52, 4319; (b) Murahashi, S.-I.; Ito,
K.-I.; Naota, T.; Maeda, Y. Tetrahedron Lett. 1981, 22,
(
2) and the Ir–dihydride complex. Then the Ir–dihydride
complex reacts with dioxygen in air to liberate water as a
by-product. In a previous paper, we reported that
5
327.
4
. Cho, C. S.; Kim, B. T.; Kim, T.-J.; Shim, S. C.
Tetrahedron Lett. 2002, 43, 7987.
Cp ZrH catalyzes efficiently the Tishchenko reaction
2
2
of aldehydes to esters through an alkoxyzirconium spe-
5. Taguchi, K.; Nakagawa, H.; Hirabayashi, T.; Sakaguchi,
S.; Ishii, Y. J. Am. Chem. Soc. 2004, 126, 72.
6. (a) Fujita, K.; Asai, C.; Yamaguchi, T.; Hanasaka, F.;
Yamaguchi, R. Org. Lett. 2005, 7, 4017; (b) Cho, C. S.;
Kim, B. T.; Kim, H.-S.; Kim, T.-J.; Shim, S. C. Organo-
metallics 2003, 22, 3608.
1
1
cies but not hemiacetal. However, it is thought that the
present reaction passes through the formation of hemi-
acetal as a transient intermediate. This is supported by
the fact that the [IrCl(coe) ] complex did not catalyze
2
2
the Tishchenko reaction of aldehydes alone in the
absence of alcohols under these conditions. A similar
7
8
9
. Matsuura, T.; Sakaguchi, S.; Obora, Y.; Ishii, Y. J. Org.
Chem. 2006, 71, 8306.
. Suzuki, T.; Matuo, T.; Watanabe, K.; Katoh, T. Synlett
8
reaction pathway is also shown by Suzuki et al.
2
005, 1453.
In conclusion, we have found that primary alcohols
undergo oxidative dimerization in the presence of a
catalytic amount of [IrCl(coe) ] under air without any
. Fujita, K.; Furukawa, S.; Yamaguchi, R. J. Organomet.
Chem. 2002, 649, 289.
10. Liu, F.; Goldman, A. S. Chem. Commun. 1999, 655.
11. Morita, K.; Nishiyama, Y.; Ishii, Y. Organometallics 1993,
2
2
additive and solvent to give the corresponding esters in
good yields. This method provides an environmentally
clean route to esters from primary alcohols and air not
using a base and a hydrogen acceptor like ketones.
1
2, 3748.
2. Britton, L. N.; Markovetz, A. J. J. Biol. Chem. 1977, 252,
561.
3. Morimoto, T.; Hirano, M.; Hamaguchi, T.; Shimoyama,
M.; Zhuang, X. Bull. Chem. Soc. Jpn. 1992, 65, 703.
4. Aneja, R.; Hollis, W. M.; Davies, A. P.; Eaton, G.
Tetrahedron Lett. 1983, 24, 4641.
1
1
1
1
8
General procedure for reaction of 1 (Table 1, entry 1): A
mixture of 1a (2 mmol) and [IrCl(coe) ] (0.06 mmol)
2
2
was stirred at 95 °C for 15 h under open air. The
product was isolated by column chromatography
5. Simpura, I.; Nevalainen, V. Tetrahedron 2001, 57,
9867.
(
230–400 mesh silica gel, n-hexane–ethyl acetate = 10:1).
16. Kim, W.-H.; Park, I.; Park, J. Org. Lett. 2006, 8, 2543.