Development of chelate resin-supported palladium catalysts for chemoselective hydrogenation

Article abstract of DOI:10.1016/j.tet.2015.03.086

Abstract Two kinds of palladium catalysts immobilized on a chelate resin bearing diiminoacetate or polyamine moieties on the polystyrene-divinylbenzene polymer were newly prepared by the adsorption of palladium (II) ions on these resins followed by the reduction to palladium (0) with hydrazine monohydrate. Both catalysts showed a similar activity for hydrogenation. A variety of reducible functionalities, except for benzylic alcohol, alkyl benzyl ether, silyl ether, and epoxide, could be reduced under the hydrogenation conditions using either catalyst. Since the palladium metal elution from the immobilized catalysts was never observed, the catalysts could be reused without any decrease in the catalyst activity for at least 5 runs.

Full text of DOI:10.1016/j.tet.2015.03.086

Tetrahedron 71 (2015) 6499e6505
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Development of chelate resin-supported palladium catalysts
for chemoselective hydrogenation
a
,
a
a
a
*
Yasunari Monguchi , Tomohiro Ichikawa , Kei Nozaki , Kensuke Kihara ,
b
b
a
a,
*
Yuuko Yamada , Yutaka Miyake , Yoshinari Sawama , Hironao Sajiki
Laboratory of Organic Chemistry, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu 501-1196, Japan
a
b
Wako Pure Chemical Industries, Ltd., 1663 Matoba, Kawagoe, Saitama 350-1101, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Two kinds of palladium catalysts immobilized on a chelate resin bearing diiminoacetate or polyamine
moieties on the polystyrene-divinylbenzene polymer were newly prepared by the adsorption of palla-
dium (II) ions on these resins followed by the reduction to palladium (0) with hydrazine monohydrate.
Both catalysts showed a similar activity for hydrogenation. A variety of reducible functionalities, except
for benzylic alcohol, alkyl benzyl ether, silyl ether, and epoxide, could be reduced under the hydroge-
nation conditions using either catalyst. Since the palladium metal elution from the immobilized catalysts
was never observed, the catalysts could be reused without any decrease in the catalyst activity for at least
5 runs.
Received 3 February 2015
Received in revised form 16 March 2015
Accepted 23 March 2015
Available online 28 March 2015
Dedicated to Professor Jiro Tsuji on the oc-
casion of his receipt of the 2014 Tetrahedron
Prize for Creativity in Organic Chemistry
Ó 2015 Elsevier Ltd. All rights reserved.
Keywords:
Chelate resin
Chemoselectivity
Hydrogenation
Palladium
Supported catalysts
6
1. Introduction
reported to have a general use execept for the semi-hydrogenation
6
hes
of disubstituted alkynes to cis-alkenes.
We have developed
The selective hydrogenation of specific functional groups in the
coexistence of multiple functionalities within a molecule is an
important technology in synthetic organic chemistry, since it is
strongly correlated with the development of new synthetic routes
heterogeneous and chemoselective palladium catalysts for the
7
hydrogenation, which were embedded on silk fibroin, poly-
8
9
10
ethylene imine, molecular sieves, boron nitride, and synthetic
11
adsorbents as the supports, and specific chemoselective hydro-
genation methods were provided due to the difference in catalyst
activities based on the properties of each support.
1
and shortening of the synthetic pathway. Chemoselective hydro-
genation is conventionally achieved by the addition of catalyst
2
poisons to control the catalyst activity. We have utilized nitrogen
DIAION CR11 and CR20, commercially available chelate resins
(Mitsubishi Chemical Corporation), bearing diiminoacetate and
polyamine moieties, respectively, as chelating functionalities on the
polystyrene-divinylbenzene-based copolymer have long been uti-
3
4
containing bases and diphenylsulfide as the appropriate catalyst
poison additives to the palladium-on-carbon (Pd/C)-catalyzed
hydrogenation system to establish several procedures for the che-
moselective method. Furthermore, such additives could also be
immobilized on Pd/C by complexation due to the coordinative
ability to the palladium metal, and the newly developed catalysts
12
lized as water purifiers based on the capture ability of metal ions.
We recently successfully developed copper catalysts for the
solvent-free Huisgen cyclization to generate 1,4-disubstituted tri-
azoles from azides and alkynes and osmium catalysts for the oxi-
dation of alkenes to diols, both of which were supported on the CR
11 and CR20 by immersing them in an aqueous solution of
5
all have their distinctive catalyst activities. It is known that the
activity of heterogeneous palladium catalysts are affected by the
characteristics of the support itself that allow the chemoselectivity
under hydrogenation conditions, but only a few catalysts were
13
3 2 2 4
Cu(NH ) $3H O and a methanolic solution of OsO , respectively.
The immobilization of palladium (II) metal on the diiminoacetate-
based chelate resin, DIAION CR10, which was previously commer-
cially available from the Mitsubishi Chemical Corporation, has been
*
Corresponding authors. Tel./fax: þ81 58 230 8109; e-mail addresses:
monguchi@gifu-pu.ac.jp (Y. Monguchi), sajiki@gifu-pu.ac.jp (H. Sajiki).
http://dx.doi.org/10.1016/j.tet.2015.03.086
0
040-4020/Ó 2015 Elsevier Ltd. All rights reserved.

6500
Y. Monguchi et al. / Tetrahedron 71 (2015) 6499e6505
studied by Hirai and Toshima,14 and Pd(II)/CR10 exhibited a hy-
1
4a,b
drogenation catalyst activity toward cyclopentadiene,
cyclo-
The DIAION CR11 has a higher
surface area, pore size, and pore volume when compared to DIAION
octadiene,1
4c,d
and acrylic acid.
14c
15
CR10, which would increase the efficiency based on the absorp-
tion (enrichment) effect of the substrates on DIAION CR11, leading
to an enhancement of the catalyst activity.
In this paper, we describe the new development of heteroge-
neous palladium catalysts supported on CR11 and CR20 and an
application for a novel and chemoselective hydrogenation method.
2
2
. Results and discussion
Fig. 2. (a) EPMA of 8% Pd/CR11 and (b) 9% Pd/CR20.
.1. Preparation and characterization of Pd/CR11 and Pd/CR20
The palladium (0) species were embedded on the chelate resins
by a sequential process via adsorption and reduction of Pd(II)
Scheme 1. The CR11 and CR20 were immersed in an EtOAc solution
of Pd(OAc) at room temperature and gently stirred for 12 h. The
2
rust-colored solution was almost totally decolored after the stir-
ring, and the white resins changed to yellow. They were collected
2
by filtration, sequentially washed with EtOAc, H O, and MeOH,
dried under reduced pressure, then stirred in an aqueous solution
of hydrazine monohydrate at room temperature for 12 h. The
resulting black catalysts, Pd/CR11 and Pd/CR20, were collected by
2
filtration, washed with MeOH and H O, and dried under reduced
pressure. The palladium contents of the 8 wt % Pd/CR11 and 9 wt %
Pd/CR20 were calculated based on the concentration of the residual
Pd in each filtrate, which was determined by atomic absorption
spectrometry.
Fig. 3. XPS spectra of 8% Pd/CR11 and 9% Pd/CR20.
2.2. 8% Pd/CR11 and 9% Pd/CR20 as hydrogenation catalysts
The catalyst activity of 8% Pd/CR11 and 9% Pd/CR20 for the hy-
Scheme 1. Preparation method of chelate resin-supported palladium catalysts (Pd/
drogenation was evaluated using substrates possessing a variety of
reducible functionalities within the molecule in MeOH. When the
reactions were incomplete at room temperature under ordinary
hydrogen pressure, the reaction temperature was raised to 40 or
CR11 and Pd/CR20).
The diameters of the Pd clusters of the 8% Pd/CR11 and 9% Pd/
CR20 were determined to be approximately 15 nm and 10 nm,
respectively, from the images of the catalyst surfaces, which were
obtained by high-angle annular dark-field scanning transmission
electron microscopy (HAADFeSTEM) (Fig. 1). An electron probe
microanalysis (EPMA) indicated that the palladium species of both
catalysts are mainly located on the catalyst surface, and almost no
palladium species are found in a deep layer of the 8% Pd/CR11
ꢀ
50 C. When the optimization was insufficient under pressurized
hydrogen, the optimal temperature was investigated under two
hydrogen conditions (3 or 5 atm). The results are summarized in
Table 1. The hydrogenation of alkyne (Entries 1, 2, and 21e25),
azido (Entries 3 and 4), nitro (Entries 5 and 6), alkene (Entries 7e10,
13e20, and 38e41), benzyl ester (Entries 7e10), and aryl benzyl
ether (Entries 11e14) functionalities smoothly proceeded at room
temperature under ordinary hydrogen pressure. The N-Cbz pro-
tecting groups of both the aliphatic and aromatic amines could be
removed (Entries 17e27); heat or pressurized hydrogen was ap-
plied when the substrates were relatively inert. On the other hand,
the alkyl benzyl ether was never deprotected (Entries 15 and 16),
while the coexisting alkene could be reduced to the corresponding
alkane. The aromatic aldehyde was completely and selectively hy-
drogenated to the corresponding benzylalcohol derivatives without
16
(
Fig. 2). The oxidation states of the palladium species of both
catalysts were determined by X-ray photoelectron spectroscopy
XPS, Fig. 3). The spectra of the 8% Pd/CR11 and 9% Pd/CR20 were
(
similar and showed the highest peaks at ca. 340.6 and 335.5 eV as
Pd3d3/2 and Pd3d5/2, respectively, for the Pd(0) species with
shoulder peaks at ca. 342.5 and 336.9 for the Pd(II) species, in-
dicating that both catalysts mainly consist of Pd(0) species, but
include a small amount of Pd(II) species.
the hydrogenolysis of the benzylic hydroxyl group (Entries 28 and
ꢀ
2
9). Although aromatic ketones were quite stable at 40 C (for
ꢀ
isobutylophenone) or 50 C (for acetophenone) under atmospheric
hydrogen conditions, the corresponding sec-benzylalcohols could
be quantitatively obtained by tuning the temperature and/or hy-
drogen pressure (Entries 30e37). It is noteworthy that the hydro-
genolysis of the benzylic hydroxyl groups never took place even at
ꢀ
5
0 C under 3 or 5 atm of H
2
pressure (Entries 35 and 37), and both
catalysts were inactive for the hydrogenation of silyl ethers, in-
cluding the relatively labile triethylsilyl ether (Entries 38e41).
Furthermore, the 8% Pd/CR11 and 9% Pd/CR20 indicated very
low catalyst activities for the hydrogenolysis of epoxides, and only
10e15% of the epoxide ring was cleaved in MeOH after 24 h when
Fig. 1. (a) HAADFeSTEM images of 8% Pd/CR11 and (b) 9% Pd/CR20.

Y. Monguchi et al. / Tetrahedron 71 (2015) 6499e6505
6501
Table 1
% Pd/CR11-and 9% Pd/CR20-catalyzed hydrogenation
8
ꢀ
Ratioa SM:1:2
Entry
Substrate
Catalyst
H
2
pressure (atm)
Temp( C)
Time (h)
Product
1
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
rt
6
6
0:100 (100)
0:100 (99)
0:100 (100)
0:100 (100)
0:100 (93)
0:100 (100)
0:100
2
3
6
4
6
5
4.5
7
6
7b
8b
9b
24
24
24
24
18
18
24
24
24
24
24
0:100
0:100
1
1
1
1
1
1
1
1
0b
0:100
1
0:100 (100)
0:100 (96)
0:100 (100)
0:100 (100)
0:100 (100)
0:100 (98)
0:9:91
2
3
4
5
6
7b
1
1
2
8b
A
B
B
3
1
3
rt
rt
rt
24
24
24
0:0:100
0:70:30
0:0:100
b
9
b
0
21
A
1
rt
24
0:63:37
2
2
2
2
2
3
4
5
A
A
B
B
1
1
1
1
40
50
rt
24
24
24
24
0:2:98
0:0:100 (100)
0:68:32
40
0:0:100 (100)
2
2
6
7
A
B
1
1
rt
rt
24
24
0:100 (85)
0:100 (66)
(
continued on next page)

6502
Y. Monguchi et al. / Tetrahedron 71 (2015) 6499e6505
Table 1 (continued )
ꢀ
Ratioa SM:1:2
Entry
Substrate
Catalyst
H
2
pressure (atm)
Temp( C)
Time (h)
Product
28
29
30
A
B
A
3
3
1
rt
24
24
24
0:100 (86)
0:100 (99)
2:98
rt
40
3
3
3
1
2
3
A
B
B
1
1
3
50
40
rt
24
24
24
0:100 (100)
7:93
0:100 (85)
34
A
1
50
24
12:88
3
3
3
5
6
7
A
B
B
3
1
5
50
50
50
24
24
24
0:100 (96)
31:68
0:100 (94)
3
3
4
4
8
9
0
1
A
B
A
B
1
1
1
1
rt
rt
rt
rt
24
24
24
24
0:100 (94)
0:100 (94)
0:100 (100)
0:100 (100)
a
Ratio was determined by 1H NMR. Isolated yields are indicated in parentheses.
b
The reaction was performed in CD
3
OD as the solvent to directly determine the ratio of the volatile starting material and/or products by 1H NMR.
Table 2
Stability of epoxide under the 8% Pd/CR11-and 9% Pd/CR20-catalyzed hydrogenation conditions
Entry
Catalyst
Solvent
Time (h)
Ratioa 1: 2: 3
1
2
3
4
5
6
7
8
A
A
A
A
A
B
B
B
MeOH
MeOH
EtOAc
THF
1,4-dioxane
MeOH
MeOH
24
3
5
5
9
24
3
8
84:11:5
92:trace:8
97:0:3
<100:0:trace
100 (97) :0:0
89:9:2
98:0:2
100 (99) :0:0
b
b
1,4-dioxane
a
Ratio was determined by 1H NMR.
Isolated yields are indicated in parentheses.
b
2
-epoxy-9-decene was used as the substrate (Table 2, Entries 1
optimal conditions could be applied to the fully selective hydro-
genation of the alkene moieties of 1,2-epoxy-7-octene and gly-
cidyl methacrylate (Table 3).
The reuse of catalysts is an important issue from environmental
and economical points of view. The reuse of the 8% Pd/CR11 and 9%
Pd/CR20 was examined using diphenylacetylene as a substrate
(Table 4). Both catalysts could be recovered and reused for at least 5
runs without any loss of catalyst activity. Furthermore, the leached
and 6). While the hydrogenative ring-opening reaction of the
epoxide was significantly observed even after 3 h (Entries 2 and 7),
the development of a total suppression method of the ring
opening of the epoxide was investigated using the coordinative
ability of ethereal solvents for the 8% Pd/CR11-catalyzed hydro-
genation due to the appropriate poisonous effect of the bulk
ethereal solvent.1
7e19
While a very small amount of alcohols were
generated in EtOAc or THF (Table 2, Entries 3 and 4), the selective
hydrogenation of only the alkene in the presence of an epoxide
could be achieved in 1,4-dioxane as the solvent (Table 2, Entry 5).
A similar chemoselective hydrogenation was achieved in the case
of 9% Pd/CR20 in 1,4-dioxane (Table 2, Entry 8). Furthermore, the
palladium species in the filtrate after the same filtration (0.2 mm
membrane filter) of the reaction mixture for the hydrogenation
using cinnamyl alcohol as the substrate were never detected
by inductively coupled plasma-atomic emission spectrometry
(ICP-AES, detection limit: <1 ppm).

Y. Monguchi et al. / Tetrahedron 71 (2015) 6499e6505
6503
Table 3
3. Conclusion
Hydrogenation of alkenes in the presence of epoxides
We have developed two types of heterogeneous palladium cat-
alysts having very similar catalyst properties and activities when
embedded on chelate resins, bearing diminoacetate moieties (CR11)
or polyamine moieties (CR20) on the polystyrene-based polymers.
Various kinds of reducible functionalities, such as alkyne, alkene,
azide, nitro, benzyl ester, N-Cbz, aromatic carbonyl, and aryl benzyl
ether functionalities, could be hydrogenated, while the hydro-
genolysis of benzyl alcohols, silyl ethers, and alkyl benzyl ethers was
hardly observed. The hydrogenative ring opening reaction of an
epoxide could be suppressed in 1,4-dioxane as the solvent. Both
catalysts could be reused for at least five runs without any loss of the
catalyst activity. Since no palladium species were leached from the
catalysts, they could be used for practical applications involving the
chemoselective and low cost hydrogenations as environmentally-
benign catalysts in industry and the laboratory. Pd/CR11 is now
commercially available from Wako Pure Chemical Industries, Ltd.
The product name and code numbers are as follows: palladium-
iminodiacetic acid, 160-26571 (1 g) and 166-26573 (5 g).
Entry
Substrate
Cat.
Time (h)
Product
Yield (%)
1
2
3
A
B
A
9
9
82
84
18
100
4
B
9
100
4
4
. Experimental section
.1. General
Table 4
Reuse of Pd/CR11 and Pd/CR20
All reagents and solvents were obtained from commercial
sources and used without further purification. Pd(OAc)
obtained from N.E. Chemcat Co. (Tokyo, Japan). The H NMR spectra
were measured by a JEOL JMN AL-400 spectrometer (400 MHz)
2
was
1
using CDCl
expressed in parts per million and internally referenced (0.00 ppm
for tetramethylsilane/CDCl or 3.30 ppm for CD OD). HAADFeSTEM,
EPMA, and XPS were measured bya JEM-ARM200F (JEOL), JXA-8230
(JEOL), and JPS-9200 (JEOL), respectively.
3 3
or CD OD as the solvent. Chemical shifts (d) were
3
3
Run
1st
2nd
3rd
4th
5th
Recovered A (%)
100
98
100
97
100
96
100
97
100
100
96
100
100
98
100
100
98
Yield (%)a
Recovered B (%)
Yield (%)a
4.2. Preparation of 8% Pd/CR11
98
99
99
a
No starting material was recovered.
A mixture of DIAION CR11 [2.00 g, water content 52.47%; 951 mg
2
(net)] in a solution of Pd(OAc) [174 mg, 0.775 mmol (82.5 mg,
palladium quantity)] in EtOAc (8 mL) was stirred under an Ar
atmosphere at rt for 12 h. The blown solid was collected on a Kir-
Fig. 4 shows the hydrogenation catalyst activity for various re-
ducible functionalities. The functionalities in each frame could be
reduced using the corresponding catalyst. The 8% Pd/CR11-and 9%
Pd/CR20-catalyzed hydrogenations could specifically exclude the
iyama funnel (1
m
m), washed with EtOAc (5 mLꢁ5), H O (5 mLꢁ5),
2
and MeOH (5 mLꢁ5), and dried under vacuum for 12 h. The filtrate
was concentrated in vacuo and then transferred to a 100 mL vol-
umetric flask with H
palladium species. The collected solid was then stirred with
NH NH $H O (117 mg, 2.33 mmol) in H O (8 mL) under Ar at rt for
2 h. The black solid was collected on a Kiriyama funnel (1 m),
washed with H
2
O. Its atomic absorption analysis detected no
2
2
2
2
1
m
2
O (5 mLꢁ5) and MeOH (5 mLꢁ5), then dried under
vacuum for 12 h to produce the Pd/CR11 (988 mg). The filtrate was
concentrated in vacuo and then transferred to a 100 mL volumetric
flask with H
.88 ppm (8.8
ladium amount, which was not captured on CR11, was found to be
.8 g, which means that the palladium ratio of Pd/CR11 was 8.3%
(82.5e0.088)/988ꢁ100].
2
O. Its atomic absorption analysis indicated that
0
mg) of the palladium species was present. The pal-
8
m
[
4.3. Preparation of 9% Pd/CR20
Fig. 4. Chemoselectivity of 8% Pd/CR11- and 9% Pd/CR20-catalyzed hydrogenations.
A mixture of DIAION CR20 [1.78 g, water content 49.0%; 908 mg
net)] in a solution of Pd(OAc) [190 mg, 0.846 mmol (90.0 mg,
2
palladium quantity)] in EtOAc (4 mL) was stirred under an Ar at-
mosphere at rt for 5 d. The blown solid was collected on a Kiriyama
hydrogenolysis of the epoxide from the frame. Although a similar
chemoselectivity was achieved by the Pd/CeNH OAc combined
4
method, the present hydrogenation required no special procedure
to remove the additives due to the totally heterogeneous catalytic
conditions without any additives and Pd leaching.
(
funnel (1
m
m), washed with H
2
O (10 mLꢁ3), and MeOH (10 mLꢁ4),
and dried under vacuum for 12 h. The filtrate was concentrated in

6504
Y. Monguchi et al. / Tetrahedron 71 (2015) 6499e6505
vacuo and then transferred to a 100 mL volumetric flask with H
Its atomic absorption analysis indicated the 15.9 ppm (1.59 mg) of
palladium species included. The collected solid was then stirred
2
O.
obtained in 97% yield (352 mg, 1.93 mmol), and the catalyst was
quantitatively recovered (23.9 mg). The reactions for the third to
fifth run were also carried out in the same manner as the first run
except for the number of used test tubes. The results are summa-
rized in the Supplementary data.
with NH
rt for 12 h. The blown solid was collected on a Kiriyama funnel
m), washed with H
2 2 2 2
NH $H O (127 mg, 2.54 mmol) in H O (3 mL) under Ar at
(
1
m
2
O (10 mLꢁ3) and MeOH (10 mLꢁ4), then
dried under vacuum for 12 h to produce the Pd/CR20 (989 mg). The
Acknowledgements
filtrate was concentrated in vacuo and then transferred to a 100 mL
2
volumetric flask with H O. No palladium species were detected by
its atomic absorption analysis. The palladium ratio of Pd/CR20 was
estimated to be 8.9% [(90.0e1.59)/989ꢁ100].
We thank the N.E. Chemcat Corporation for the ICP-AES mea-
surement of the eluted palladium species from the catalysts into
the reaction mixure. We also thank the Mitsubish Chemical Cor-
poration for their kind gifts of DIAION CR11 and CR20 and providing
information about the resins.
4
.4. General procedure for the hydrogenation
A mixture of the substrate (0.250 mmol) and catalyst [8% Pd/
CR11 (3.3 mg, 2.50
MeOH (1 mL) was stirred under an H
room temperature. After a specific time, the mixture was filtered
through a membrane filter (0.45 or 0.2 m), and the filtrate was
mmol) or 9% Pd/CR20 (3.0 mg, 2.50
mmol)] in
Supplementary data
2
atmosphere (balloon) at
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.tet.2015.03.086.
m
concentrated in vacuo to give the corresponding spectrometrically-
pure reduced product. If the reaction was not completed, the
temperature was raised to 40 or 50 C. If the reaction was still in-
References and notes
ꢀ
complete, the H
2
pressure was increased to 3 or 5 atm. All the
1. (a) Sajiki, H.; Monguchi, Y. In Pharmaceutical Process Chemistry; Shioiri, T., Izawa,
K., Konoike, T., Eds.; WILEY-VCH: Weinheim, Germany, 2010; pp 77e99; (b)
Yabe, Y.; Sawama, Y.; Monguchi, Y.; Sajiki, H. Catal. Sci. Technol. 2014, 4,
1
products were known, and the H NMR spectral data of the prod-
ucts were identical to those in the literature (see Supplementary
data).
260e271; (c) Sajiki, H. J. Org. Synth. Chem. Jpn. 2014, 72, 39e50.
2. (a) Lindlar, H. Helv. Chim. Acta 1952, 35, 446e450; (b) Lindlar, H.; Dubuis, R. Org.
Synth. Coll. 1973, 5, 880e882; (c) Rosenmund, K. W. Ber. Dtsch. Chem. Des. 1918,
5
4
1, 585e594; (d) Rosenmund, K.; Zetzsche, F. Ber. Dtsch. Chim. Ges. 1921, 54B,
25e437.
4
.5. Reuse test of 8% Pd/CR11
3
. (a) Sajiki, H. Tetrahedron Lett. 1995, 36, 3465e3468; (b) Sajiki, H.; Kuno, H.;
Hirota, K. Tetrahedron Lett. 1997, 38, 399e402; (c) Sajiki, H.; Kuno, H.; Hirota, K.
Tetrahedron Lett. 1998, 39, 7127e7130; (d) Sajiki, H.; Hirota, K. Tetrahedron 1998,
Ten test tubes were prepared, and diphenylacetylene (44.6 mg,
0
.250 mmol), 8% Pd/CR11 (3.3 mg, 2.50 mmol, 1 mol %), and MeOH
5
4, 13981e13996; (e) Sajiki, H. Yakugaku Zasshi 2000, 120, 1091e1103; (f) Sajiki,
H.; Hirota, K. Chem. Pharm. Bull. 2003, 51, 320e324.
4. (a) Mori, A.; Miyakawa, Y.; Ohashi, E.; Haga, T.; Maegawa, T.; Sajiki, H. Org. Lett.
006, 8, 3279e3281; (b) Mori, A.; Mizusaki, T.; Miyakawa, Y.; Ohashi, E.; Haga,
(
1 mL) were placed in each test tube. The mixture in each test tube
was stirred under an H atmosphere (balloon) at room temperature
for 6 h, then all the mixtures were filtered using a Kiriyama funnel
m filter paper). The catalyst on the filter paper was washed with
EtOAc (10 mL),and the filtrate was concentrated in vacuo to give
,2-diphenylethane in 98% yield (445 mg, 2.44 mmol). The re-
2
2
T.; Maegawa, T.; Monguchi, Y.; Sajiki, H. Tetrahedron 2006, 62, 11925e11932.
. For Pd/C-ethylenediamine complex: (a) Sajiki, H.; Hattori, K.; Hirota, K. J. Org.
Chem. 1998, 63, 7990e7992; (b) Sajiki, H.; Hattori, K.; Hirota, K. J. Chem. Soc.,
Perkin Trans. 1 1998, 4043e4044; (c) Sajiki, H.; Hattori, K.; Hirota, K. Chem.
Commun. 1999, 1041e1042; (d) Hattori, K.; Sajiki, H.; Hirota, K. Tetrahedron Lett.
(1 m
5
1
covered catalyst was dried at room temperature under reduced
2
000, 41, 5711e5714; (e) Sajiki, H.; Hattori, K.; Hirota, K. Chem.dEur. J. 2000, 6,
pressure for 12 h, then weighed [32.9 mg, 100%, 32.9 O (3.3ꢁ10)ꢁ
2200e2204; (f) Hattori, K.; Sajiki, H.; Hirota, K. Tetrahedron 2000, 56,
8433e8441; (g) Hattori, K.; Sajiki, H.; Hirota, K. Tetrahedron 2001, 57,
100]. The reaction for the second run was carried out in the same
2109e2114; (h) Hattori, K.; Sajiki, H.; Hirota, K. Tetrahedron 2001, 57,
manner as the first run, but using eight test tubes [total substrate
amount, 357 mg (44.6 mgꢁ8), 2.00 mmol (0.250 mmolꢁ8), total
catalyst amount, 26.4 mg (3.3 mgꢁ8)]. 1,2-Diphenylethane was
obtained in 96% yield (350 mg, 1.92 mmol), and the catalyst was
quantitatively recovered (26.8 mg). The reactions for the third to
fifth runs were also carried out in the same manner as the first run
except for the number of used test tubes. The results are summa-
rized in the Supplementary data.
4
817e4824; (i) Sajiki, H.; Hirota, K. J. Org. Synth. Chem. Jpn. 2001, 59, 109e120
For Pd/C-diphenylsulfide complex; (j) Mori, A.; Mizusaki, T.; Kawase, M.;
Maegawa, T.; Monguchi, Y.; Takao, S.; Takagi, Y.; Sajiki, H. Adv. Synth. Catal.
2008, 350, 406e410.
6
. For supported palladium catalysts: (a) Lee, H.-Y.; Ryu, S.; Kang, H.; Jun, Y.-w;
Cheon. J. Chem. Commun. 2006, 1325e1327; (b) Hagiwara, H.; Nakamura, T.;
Hoshi, T.; Suzuki, T. Green Chem. 2011, 13, 1131e1137; (c) Armbr u€ ster, M.;
Behrens, M.; Cinquini, F.; F o€ ttinger, K.; Grin, Y.; Haghofer, A.; Kl o€ tzer, B.; Knop-
Gericke, A.; Lorenz, H.; Ota, A.; Penner, S.; Prinz, J.; Rameshan, C.; R eꢀ vay, Z.;
Rosenthal, D.; Rupperchter, G.; Sautet, P.; Schl o€ gl, R.; Shao, L.; Szentmikl oꢀ si, L.;
Teschner, D.; Torres, D.; Wagner, R.; Widmer, R.; Wowsnick, G. ChemCatChem
ꢀ
ꢀ
€
ꢀ
2
2
012, 4, 1048e1063; (d) Mastalir, A.; Kiraly, Z.; Szollosi, G.; Barok, M. J. Catal.
000, 194, 146e152; (e) Gruttadauria, M.; Liotta, L. F.; Noto, R.; Deganello, G.
4
.6. Reuse test of 9% Pd/CR20
ꢀ
ꢀ
Tetrahedron Lett. 2001, 42, 2015e2017; (f) Mastalir, A.; Kiraly, Z. J. Catal. 2003,
220, 372e381; (g) Panpranol, J.; Phandinthong, K.; Sirikajorn, T.; Arai, M.;
Praserthdam, P. J. Mol. Catal. A: Chem. 2007, 261, 29e35; (h) Domínguez-
Ten test tubes were prepared, and diphenylacetylene (44.6 mg,
.250 mmol), 9% Pd/CR20 (3.0 mg, 2.50 mmol, 1 mol %), and MeOH
0
ꢀ
ꢀ
Domínguez, S.; Berenguer-Murcia, A.; Pradhan, B. K.; Linarse-Solano, A.; Car-
(
1 mL) were placed in each test tube. The mixture in each test tube
was stirred under an H atmosphere (balloon) at room temperature
for 6 h, then all the mixtures were filtered using a Kiriyama funnel
m filter paper). The catalyst on the filter paper was washed with
EtOAc (10 mL),and the filtrate was concentrated in vacuo to give
,2-diphenylethane in 97% yield (442 mg, 2.43 mmol). The re-
zorla-Amor oꢀ s, D. J. Phys. Chem. C 2008, 112, 3827e3834; (i) Weerachawanask,
2
P.; Mekasuwandumrong, O.; Arai, M.; Fujita, S.-I.; Praserthdam, P.; Panpranol, J.
J. Catal. 2009, 262, 199e205; (j) Shao, Z.; Li, C.; Chen, X.; Pang, M.; Wang, X.;
Liang, C. ChemCatChem 2010, 2, 1555e1558; (k) Zhao, Y.; Liu, Q.; Li, J.; Liu, Z.;
Zhou, B. Synlett 2010, 1870e1872; (l) Armbr u€ ster, M.; Kovnir, K.; Behrens, M.;
(1 m
Teschner, D.; Grin, Y.; Schlogl, R. J. Am. Chem. Soc. 2010, 132, 14745e14747; (m)
Ota, A.; Armbr
€
u€ ster, M.; Behrens, M.; Rosenthal, D.; Friedrich, M.; Kasatkin, I.;
1
Girgsdies, F.; Zhang, W.; Wagner, R.; Schl o€ gl, R. J. Phys. Chem. C 2011, 115,
covered catalyst was dried at room temperature under reduced
1
2
368e1374; (n) Tew, M. W.; Emerich, H.; van Bokhoven, J. A. J. Phys. Chem. C
011, 115, 8457e8465 For palladium nanoparticles: (o) Vasylyev, M. V.; Maayan,
G.; Hovav, Y.; Haimov, A.; Neumann, R. Org. Lett. 2006, 8, 5445e5448; (p) Le
Bras, J.; Mukherjee, D. K.; Gonz aꢀ lez, S.; Tristany, M.; Ganchegui, B.; Moreno-
Ma nꢁ as, M.; Pleixats, R.; Henin, F.; Muzart, J. New J. Chem. 2004, 28, 1550e1553;
pressure for 12 h, then weighed [30.2 mg, 100%, 30.2 O (3.0ꢁ10)ꢁ
100]. The reaction for the second run was carried out in the same
manner as the first run, but using eight test tubes [total substrate
amount, 357 mg (44.6 mgꢁ8), 2.00 mmol (0.250 mmolꢁ8), total
catalyst amount, 24.0 mg (3.0 mgꢁ8)]. 1,2-Diphenylethane was
(
q) Thiery, E.; Le Bras, J.; Muzart, J. Green. Chem. 2007, 9, 326e327; (r) Callis, N.
M.; Thiery, E.; Le Bras, J.; Muzart, J. Tetrahedron Lett. 2007, 48, 8128e8131; (s)

Y. Monguchi et al. / Tetrahedron 71 (2015) 6499e6505
6505
Hori, J.; Murata, K.; Sugai, T.; Shinohara, H.; Noyori, R.; Arai, N.; Kurono, N.;
Ohkuma, T. Adv. Synth. Catal. 2009, 351, 3143e3149.
1986, A23, 933e954; (c) Toshima, N.; Teranishi, T.; Saito, Y. Makromol. Chem.,
Macromol. Symp. 1992, 59, 327e341; (d) Teranishi, T.; Toshima, N. J. Chem. Soc.,
Dalton Trans. 1994, 2967e2974.
7
. (a) Sajiki, H.; Ikawa, T.; Hirota, K. Tetrahedron Lett. 2003, 44, 171e174; (b) Sajiki,
H.; Ikawa, T.; Hirota, K. Tetrahedron Lett. 2003, 44, 8437e8439; (c) Ikawa, T.;
Sajiki, H.; Hirota, K. Tetrahedron 2005, 61, 2217e2231; (d) Kitamura, Y.; Tanaka,
A.; Sato, M.; Oono, K.; Ikawa, T.; Maegawa, T.; Monguchi, Y.; Sajiki, H. Synth.
Commun. 2007, 37, 4381e4388; (e) Ikawa, T.; Sajiki, H.; Hirota, K. J. Org. Synth.
Chem. Jpn. 2005, 63, 1218e1231.
15. The general properties of DIAION CR10, CR11, and CR20 (Mitsubishi Chemical
data).
8
. (a) Sajiki, H.; Mori, S.; Ohkubo, T.; Ikawa, T.; Kume, A.; Maegawa, T.; Monguchi,
Y. Chem.dEur. J. 2008, 14, 5109e5111; (b) Mori, S.; Ohkubo, T.; Ikawa, T.; Kume,
A.; Maegawa, T.; Monguchi, Y.; Sajiki, H. J. Mol. Catal. A: Chem. 2009, 307, 77e87.
. (a) Maegawa, T.; Takahashi, T.; Yoshimura, M.; Suzuka, H.; Monguchi, Y.; Sajiki,
H. Adv. Synth. Catal. 2009, 351, 2091e2095; (b) Takahashi, T.; Yoshimura, M.;
Suzuka, H.; Maegawa, T.; Sawama, Y.; Monguchi, Y.; Sajiki, H. Tetrahedron 2012,
9
6
8, 8293e8299.
10. (a) Yabe, Y.; Yamada, T.; Nagata, S.; Sawama, Y.; Monguchi, Y.; Sajiki, H. Adv.
Synth. Catal. 2012, 354, 1264e1268; (b) Yabe, Y.; Sawama, Y.; Monguchi, Y.;
Sajiki, H. Chem.dEur. J. 2013, 19, 484e488; (c) Kawanishi, A.; Miyamoto, C.;
Yabe, Y.; Inai, M.; Asakawa, T.; Hamashima, Y.; Sajiki, H.; Kan, T. Org. Lett. 2013,
15, 1306e1309; (d) Yabe, Y.; Sawama, Y.; Yamada, T.; Nagata, S.; Monguchi, Y.;
Sajiki, H. ChemCatChem 2013, 5, 2360e2366.
1
1. (a) Monguchi, Y.; Fujita, Y.; Endo, K.; Takao, S.; Yoshimura, M.; Takagi, Y.;
Maegawa, T.; Sajiki, H. Chem.dEur. J. 2009, 15, 834e837; (b) Monguchi, Y.; Sakai,
K.; Endo, K.; Fujita, Y.; Niimura, M.; Yoshimura, M.; Mizusaki, T.; Sawama, Y.;
Sajiki, H. ChemCatChem 2012, 4, 546e558; (c) Monguchi, Y.; Sajiki, H. J. Synth.
Org. Chem. Jpn. 2012, 70, 711e721.
1
6. The difference in the palladium particle size on the catalyst surface between 8%
Pd/CR11 and 9% Pd/CR20 would be solely attributed to the palladium density,
thus the more condensed palladium on the Pd/CR11 surface should form larger
particles in comparison to Pd/CR20.
1
7. The retention of the epoxide could be achieved by the Pd/C(en)-catalyzed hy-
drogenation inTHF, while the use of MeOH as the solvent led to the regioselective
cleavage of the terminal epoxides to the corresponding secondary alcohols; see:
reference 5e and the following reference. Sajiki, H.; Hattori, K.; Hirota, K. Chem.
Commun. 1999, 1041e1042.
1
2. (a) Home page for DIAION of Mitsubishi Chemical Co., see http://www.diaion.
com/Index_E.htm; (b) Koivula, R.; Lehto, J.; Pajo, L.; Gale, T.; Leinonen, H.
Hydrometallurgy 2000, 56, 93e108; (c) Cavaco, A.; Fernandes, S.; Quina, M. M.;
Ferreira, L. M. J. Hazard. Mater. 2007, 144, 634e638; (d) Cavaco, S. A.; Fernandes,
S.; Augusto, C. M.; Quina, M. J.; Gando-Ferreira, L. M. J. Hazard. Mater. 2009, 169,
18. A similar solvent effect has been used for the partial and selective hydroge-
5
1
16e523; (e) Gando-Ferreira, L. M.; Romao, I. S.; Quina, M. J. Chem. Eng. J. 2011,
72, 277e286.
3. (a) Monguchi, Y.; Nozaki, K.; Maejima, T.; Shimoda, Y.; Sawama, Y.; Kitamura, Y.;
nation of alkynes to the corresponding alkenes, catalyzed by polyethylene
8
imine-supported palladium (Pd/PEI); see reference .
1
19. The difference in the swellability of the catalyst by solvent might affect the
Kitade, Y.; Sajiki, H. Green Chem. 2013, 15, 490e495; (b) Monguchi, Y.;
Wakayama, F.; Takada, H.; Sawama, Y.; Sajiki, H. Synlett 2015, 700e704.
ring-opening reaction of epoxides, but any evidences were not obtained.
14. (a) Hirai, H.; Komatsuzaki, S.; Toshima, N. Bull. Chem. Soc. Jpn. 1984, 57,
488e494; (b) Hirai, H.; Komatsuzaki, S.; Toshima, N. J. Macromol. Sci., Chem.