2
378
J . Org. Chem. 1998, 63, 2378-2381
Ta ble 1. Effect of Solven ts on th e Hom ogen eou s a n d
Heter ogen eou s Hyd r ogen a tion s of Cin n a m a ld eh yd e (1)
Ch em oselective Tr a n sfer Hyd r ogen a tion of
r,â-Un sa tu r a ted Ald eh yd es to Allylic
Alcoh ols Usin g F or m ic Acid Ca ta lyzed by
P olym er -Bou n d Rh Ca r bon yl Clu ster s
a ,b
Usin g Rh 6(CO)16
d
selectivity (%)
convn
solvent
THF
,4-dioxane
THP
toluene
MeOH
DSc
of 1d (%)
2
3
4
2.7
1.8
1.5
2.1
1.2
91 (86)
99 (89)
95 (88)
99 (0)
91 (89)
82 (85)
82 (87)
66 (-)
72 (-)
1 (1)
1 (2)
2 (1)
2 (-)
24 (-)
8 (10)
17 (13)
16 (12)
32 (-)
4 (-)
Tomoo Mizugaki, Yoshinori Kanayama,
Kohki Ebitani, and Kiyotomi Kaneda*
1
Department of Chemical Science and Engineering, Graduate
School of Engineering Science, Osaka University,
10 (0)
a
1
-3 Machikaneyama, Toyonaka, Osaka 560, J apan
Reaction conditions: 1 (1.0 mmol), Rh6(CO)16 (0.005 mmol),
formic acid (2.0 mmol), 4-DMAP (2.0 mmol), solvent (3.0 mL), PCO
)
5 atm, 30 °C, 5 h. b Values in parentheses are for the hetero-
geneous system; POLYDMAP (100 mg, 0.14 mmol equiv of DMAP)
Received October 21, 1997
was used. c Degree of swelling of the POLYDMAP. DS: degree of
swelling, Swollen resin volume/dry resin volume. Determined by
Chemoselective hydrogenation of R,â-unsaturated car-
bonyl compounds to the corresponding allylic alcohols has
been continuously studied due to the high potential
utility of allylic alcohols.1 We have already reported that
d
GC using internal standard technique. 2, unsaturated alcohol; 3,
saturated aldehyde; 4, saturated alcohol.
6
the catalyst system consisting of Rh (CO)16 and amines
transfer hydrogenation of R,â-unsaturated aldehydes to
had high activities for the hydrogenation of R,â-unsatur-
allylic alcohols using formic acid, where higher catalytic
ated aldehydes under the water-gas shift reaction condi-
activities were obtained than when H
2
O or H
2
was the
2
tions or in the presence of hydrogen and carbon mon-
2,3
hydrogen source.
The homogeneous catalyst system
oxide.3 Using aminated polystyrenes, the above catalyst
system could be heterogenized to form polymer-bound Rh
cluster complexes that showed high performances of
could be heterogenized with POLYDMAP as an aminated
polystyrene support8 to form a catalyst that could be
recycled without loss of high activities and selectivities
for the above hydrogenations (eq 1).
4
,5
recoverable and reusable catalysts.
In the case of hydrogenations of carbonyl compounds
to alcohols, formic acid or 2-propanol as a hydrogen
6
source has been interesting from the standpoint of safety
and using environmentally benign reagents.7 In this
paper, we used the Rh-amine catalyst system in the
*
To whom correspondence should be addressed. Tel.: +81-6-850-
6
260. Fax: +81-6-850-6296. E-mail: kaneda@cheng.es.osaka-u.ac.jp.
(
1) For typical hydrogenations of R,â-unsaturated carbonyl com-
pounds to allylic alcohols using metal complex catalysts: (a) Ohkuma,
T.; Ooka, H.; Ikariya, T.; Noyori, R. J . Am. Chem. Soc. 1995, 117,
1
0417. (b) Planeix, J . M.; Coustel, N.; Coq, B.; Brotons, V.; Kumbhar,
P. S.; Dutartre, R.; Geneste, P.; Bernier, P.; Ajayan, P. M. J . Am. Chem.
Soc. 1994, 116, 7935. (c) Fache, E.; Mercier, C.; Pagnier, N.; Despey-
roux, B.; Panster, P. J . Mol. Catal. 1993, 79, 117. (d) Mashima, K.;
Akutagawa, T.; Zhang, X.; Takaya, H.; Taketomi, H.; Kumobayashi,
H.; Akutagawa, S. J . Organomet. Chem. 1992, 428 213. (e) Lau, C. P.;
Ren, C. Y.; Chu, M. T.; Yeung, C. H. J . Mol. Catal. 1991, 65, 287. (f)
Grosselin, J . M.; Mercier, C.; Allmang, G.; Gruss, F. Organometallics
1
. Hom ogen eou s Hyd r ogen a tion s. In order to
attain highly chemoselective reductions of aldehyde
functions in the presence of formic acid as a reductant,
various reaction conditions (e.g., CO pressures, additives,
reaction temperatures, and solvents) were scrutinized in
the homogeneous hydrogenation of cinnamaldehyde as
a model substrate. This selective hydrogenation needed
base additives as was also found in our previous hydro-
genations using H
-(Dimethylamino)pyridine (4-DMAP) was found to be
the best additive, while diamines as bases were effective
1
991, 10, 2126. (g) B e´ nyei, A.; J o o´ , F. J . Mol. Catal. 1990, 58, 151. (h)
De Martin, S.; Zassinovich, G.; Mestroni, G. Inorg. Chim. Acat 1990,
74, 9. (i) Mizoroki, T.; Seki, K.; Meguro, S.; Ozaki, A. Bull. Chem.
Soc. J pn.1977, 50, 2148.
2) Kaneda, K.; Yasumura, M.; Imanaka, T.; Teranishi, S. J . Chem.
Soc., Chem. Commun. 1982, 935.
1
(
(
3) Kaneda, K.; Mizugaki, T. Organometallics 1996, 15, 3247.
2
,3
(4) Excellent reviews and books on polymer-bound metal complex
2 2
O or H as a hydrogen source.
catalysts: (a) Bergbreiter, D. E. CHEMTECH 1987, 17, 686. (b)
Pittman, C. U. In Comprehensive Organometallic Chemistry; Wilkin-
son, G.; Ed., Pergamon: Oxford, 1982; p 553. (c) Whitehurst, D. D.
CHEMTECH 1980, 10, 44. (d) Mathur, N. K.; Narang, C. K.; Williams,
R. E. Polymers as Aids in Organic Chemistry; Academic Press: New
York, 1980. (e) Grubbs, R. H. CHEMTECH 1977, 7, 512.
4
2,3
in the case of H
2
O or H
2
.
Further CO was essential
for the hydrogenation, and at least 5 atm of CO was
necessary for the efficient formation of cinnamyl alcohol.
Hardly any hydrogenation occurred under a nitrogen
atmosphere without any CO. The highest selectivity for
the unsaturated alcohol was attained at 30 °C, and
hydrogenations at higher temperatures resulted in poor
selectivity to allylic alcohols. Table 1 shows the effect of
solvents on the homogeneous hydrogenation using formic
acid together with that of the corresponding heteroge-
(5) For our work on catalysis of the polymer-bound Rh cluster
complexes see: (a) Mizugaki, T.; Ebitani, K.; Kaneda, K. Appl. Surf.
Sci. 1997, 121/122, 360. (b) Mizugaki, T.; Ebitani, K.; Kaneda, K.
Tetrahedron Lett. 1997, 38, 3005. (c) Reference 3. (d) Kaneda, K.;
Kuwahara, H.; Imanaka, T. J . Mol. Catal. 1994, 88, L267. (e) Kaneda,
K.; Takemoto, T.; Kitaoka, K.; Imanaka, T. Organometallics 1991, 10,
8
46.
6) For reviews on transfer hydrogenations: (a) Zassinovich, G.;
(
Mestroni, G.; Gladiali, S. Chem. Rev. 1992, 92, 1051. (b) Ram, S.;
Ehrenkaufer, R. E. Synthesis 1988, 91. (c) J ohnstone; A. H.; Wilby, R.
A. W.; Entwistle, I. D. Chem. Rev. 1985, 85, 129. (d) Brieger, G.;
Nestrick, T. J . Chem. Rev. 1973, 74, 567.
(
7) (a) Cornils, B.; Wiebus, E. CHEMTECH 1995, 25, 33. (b)
Herrmann, W. A.; Kohlpaintner, C. A. Angew. Chem., Int. Ed. Engl.
993, 32, 1524.
(8) POLYDMAP is ca. 4% cross-linked gel beads with particle sizes
between 30 and 80 U.S. mesh (>80%). The 4-DMAP equivalence of
this polymer is 1.4 mmol equiv/g (dry polymer).
1
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Published on Web 03/17/1998