Concerted Catalysis in Tight Spaces: Palladium-Catalyzed Allylation Reactions Accelerated by Accumulated Active Sites in Mesoporous Silica

Article abstract of DOI:10.1002/cctc.201700439

The surface of mesoporous silica was modified with a Pd–bisphosphine complex and/or a tertiary amine group for concerted acceleration of allylation reactions. Mesoporous-silica-supported catalysts with a 1.6 nm pore diameter showed higher performance than nonporous or larger mesoporous silica-supported catalysts owing to the accumulation of active sites into a confined space. For the case in which allyl alcohol was used in the reaction, the presence of a silanol group on the surface was quite effective: the turnover number of Pd was nine times greater than that of the homogeneous Pd complex.

Full text of DOI:10.1002/cctc.201700439

Accepted Article
Title: Concerted Catalysis in Tight Spaces: Palladium-Catalyzed
Allylation Reactions Accelerated by Accumulated Active Sites in
Mesoporous Silica
Authors: Ken Motokura, Marika Ikeda, Masayuki Nambo, Wang-Jae
Chun, Kiyotaka Nakajima, and Shinji Tanaka
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10.1002/cctc.201700439
ChemCatChem
COMMUNICATION
Concerted Catalysis in Tight Spaces: Palladium-Catalyzed
Allylation Reactions Accelerated by Accumulated Active Sites in
Mesoporous Silica
Ken Motokura*,[a] Marika Ikeda,[a] Masayuki Nambo,[a] Wang-Jae Chun,[b] Kiyotaka Nakajima,[c] and
Shinji Tanaka[d]
Abstract: The mesoporous silica surface was modified with a Pd-
bisphosphine complex and/or a tertiary amine group for concerted
acceleration of allylation reactions. Mesoporous silica-supported
catalysts with 1.6 nm pore diameter showed a higher performance
than nonporous or larger mesoporous silica-supported catalysts due
to the accumulation of active sites into a confined space. In case of
the reaction using allylic alcohol, the presence of the silanol group
on the surface was quite effective: the turnover number (TON) of Pd
was nine times more than that of the homogeneous Pd complex.
have high potential for the support of accumulated multi-
functionalities, such as metal complexes and organic bases, for
concerted catalysis.
Another important issue with the Pd-catalyzed allylation
reaction is the use of less reactive allylic substrates. Allylic
alcohol is one of the most desirable allylating agents because
the use of allylic alcohol enables minimizing the waste formation
by producing only water as a by-product.[20,21] To promote the
reaction with allylic alcohol, the use of protonic acid as a co-
catalyst is highly effective [22-28]; allylic alcohol can be activated
by the hydrogen bond of its hydroxyl group with several weak
and strong protonic acids. These facts motivated us to examine
the effect of Si-OH groups formed on silica support on the allylic
alcohol activation.
Herein, we would like to demonstrate a novel concept for
concerted catalysis on the surface: the accumulation of active
sites in a tight mesopore space, as shown in Figure 1. The
accumulated functions, Pd complexes, tertiary amines, and
silanol groups can activate allylating agents, nucleophiles, and
leaving groups of allylic alcohol (OH), respectively, resulting in
highly efficient allylation reactions.
Concerted catalysis between metal complexes and organic
functional groups is
a notable strategy to create novel
heterogeneous catalysis and
a highly efficient molecular
transformation technique.[1] Several research groups reported
Pd,[2-10] Rh,[11] and Cu complexes
immobilized on solid
[12,13]
surfaces with other organic functionalities for efficient
transformation of organic molecules. In the case of concerted
catalysis with Pd complexes, the allylation of nucleophiles was
effectively accelerated by the assistance of the basic amine
group: both allylic substrates and nucleophiles were activated by
Pd complexes and bases, respectively.[14,15]
Despite the need for more research on the concerted catalysis
on solid surfaces, the effect of the support structure on the
catalysis between immobilized metal complexes and organic
bases has been scarcely studied. In the case of mesoporous
support with an appropriate pore diameter, it can be expected
that the two immobilized functional groups effectively
“Three-Dimensional” Accumulation
in Mesopore
Allylating Agent Activation
Nucleophile Activation
Leaving Group
(OH) Activation
9.0 Å
5.5 Å
approached each other for the synergistic activation of substrate
[16-19]
molecules
due to the restricted reaction space. In fact,
Jones et al. demonstrated that the cooperative catalysis of
amine-silanol for aldol reaction was significantly affected by the
size of pore diameter.[19] In other words, mesoporous materials
Nonporous support
Mesoporous support
Figure 1. Concept of mesoporous silica (MS)-supported catalyst design for the
Pd-catalyzed allylation reactions.
[a]
Dr. K. Motokura, M. Ikeda, M. Nambo
Department of Chemical Science and Engineering, School of
Materials and Chemical Technology
Tokyo Institute of Technology
The distance from the silicon atom to the Pd center and
nitrogen atom for the Pd-bisphosphine complex (PP-Pd) and 3-
diethylaminopropyltrimethoxysilane are approximately 9.0 and
5.5 Å, respectively (Figure 1). We predicted that mesoporous
silica (MS) with pore diameters of ~2 nm was suitable for
accumulation of these functional groups for concerted catalysis.
Various MS supports with different pore diameters in the range
of 1.6-3.1 nm were prepared by using primary amine with C8 to
C18 alkyl chain as a structure-directing agent.[29] These MS
supports are denoted as MS(C8) to MS(C18). SBA-16 was also
used as a reference material with large-sized pores and three-
dimensional porous network that enhances diffusion and access
of reactant molecules to catalytically active sites.[30] The
physicochemical properties of MS are summarized in Table S1
in Supporting Information (SI). The MS samples exhibited high
surface areas (855-1865 m2g-1) and narrow pore size
4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8502, Japan
E-mail: motokura.k.ab@m.titech.ac.jp
Prof. Dr. W.-J. Chun
Graduate School of Arts and Sciences
International Christian University
Mitaka, Tokyo, 181-8585, Japan
Dr. K. Nakajima
Institute for Catalysis
Hokkaido University
Kita 20, Nishi 10, Kita-ku, Sapporo 001-0021, Japan
Dr. S. Tanaka
[b]
[c]
[d]
Interdisciplinary Research Center for Catalytic Chemistry
National Institute of Advanced Industrial Science and Technology
(AIST)
Central 5, Higashi 1-1-1, Tsukuba, Japan
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/cctc.201700439
ChemCatChem
COMMUNICATION
OEt
1,5
B
C
D
A
6
4
2
0
OEt
Pd-P/Cl
k
OMe
Si
MS(C12)/NEt2/PP-Pd
2
Ph
1 mm
4
3
distance
k
k
P
Pd
*
*
PP-Pd
0
1
2
3
4
5
6
r / Å
distance
distance
60
40
20
0
-20
-40
120
80
40
0
31P Chemical Shift / ppm
13C Chemical Shift / ppm
Figure 2. (A) SEM image of MS(C8)/NEt2/PP-Pd and line analysis results for Si, P, and Pd elements, (B) 13C CP/MAS NMR spectrum of MS(C12)/NEt2/PP-Pd,
(C) 31P NMR spectrum of CDCl3 solution of PP-Pd and 31P MAS NMR spectrum of MS(C12)/NEt2/PP-Pd, and (D) FT of k3-weighted Pd K-edge EXAFS spectrum
of MS(C12)/NEt2/PP-Pd.
distributions (1.6-5.3 nm) (Table S1, Figures S1-S3), with the
complete removal of structure-directing agents proven by
elemental analysis and 13C CP MAS NMR measurments.
Nonporous silica (SiO2, Aerosil300) was also used as a support
material to check the effect of mesoporous structre.
Surface functionalization procedure is shown in Scheme 1.
The tertiary amine group was immobilized on the MS internal
surface by the simple silane-coupling reaction resulting in MS-
supported tertiary amine (MS/NEt2). A Pd-bisphosphine complex
with a triethoxysilyl group (PP-Pd) was prepared in line with our
previous method.[10] The Pd complex was introduced to the
MS/NEt2 surface to form MS-supported tertiary amine and PP-
Pd (MS/NEt2/PP-Pd). MS with only the Pd complex (MS/PP-Pd)
was also prepared by a similar process.
Elemental analysis results of the prepared samples are
summarized in Table S2 in SI. The Pd loading was around 0.3-
0.4 mmol g-1 for MS-supported samples. The amounts of
nitrogen and carbon in MS/NEt2/PP-Pd were much higher than
thoes in MS/PP-Pd, suggesting the presence of a tertiary amine
group with PP-Pd. The almost identical amounts of Cl and Pd
indicate the presence of the PP-Pd complex.
Small angle XRD analysis revealed that original mesoporous
structure was flluly maintained even after the immobilization of
organic functionalities. SEM line analysis results are
summarized in Figure 2A. The presence of phosphorus and
palladium inside the MS(C8) particle was clearly demonstrated
suggesting the existence of immobilized functionalities in the
mesopore. The chemical structures of immobilized tertiary amine
and PP-Pd were determined by solid-state NMR and Pd K-edge
X-ray absorption fine structure (XAFS) measurements. The
attachment of functionalities on the MS surface through silane-
coupling reaction was confirmed by 29Si MAS NMR
measurement: the decrease in the Q3 site (-100 ppm;
Si(OH)1(OSi)3) of MS and the generation of T sites (-60~-70
ppm; SiR(OR’)3) were detected after the immobilization (Figure
S6, SI). Figure 2B represents solid-state 13C CP/MAS NMR
spectrum of MS(C12)/NEt2/PP-Pd. The maintenance of tertiary
amine structure was confirmed by the 13C NMR signal positions
(1~5). The detailed comparison of homogeneous precursors and
immobilized material is shown in Figure S7 in SI. The presence
of a phenyl group in the PP-Pd complex was also detected
around 120-140 ppm, however, other signals of the PP-Pd
complex were not clearly detected due to their low intensity.[10]
To confirm the coordination of the phosphine ligand to the Pd
center after immobilization, 31P MAS NMR measurement was
conducted as shown in Figure 2C. The presence of a sharp
signal around 0 ppm strongly indicates the coordination of P
atoms to Pd in the complex attached to the MS surface.
Pd K-edge X-ray absorption near-edge structure (XANES)
spectra of MS/NEt2/PP-Pd, MS/PP-Pd, SiO2/NEt2/PP-Pd, and
reference samples are shown in Figure S9 in SI. The spectra of
supported Pd complex were almost identical. Their spectral
features were similar to PdCl2(PPh3)2, but completely different
from PdO and Pd foil. Figure S10 in SI represents k3-weighted
extended X-ray absorption fine structure (EXAFS) spectra of
supported Pd complexes along with the THF solution of the PP-
Pd precursor. Similar EXAFS spectra of these samples indicate
that the local structure of the Pd complex is not affected by the
immobilization on the support surface or by the presence of
tertiary amine. Fourier transform (FT) of the k3-weighted EXAFS
spectra of MS(C12)/NEt2/PP-Pd is shown in Figure 2D. A strong
peak at 1.8 Å was observed and the comparison of this
spectrum with PdCl2(PPh3)2 suggested that the peak could be
assigned as Pd-P or Pd-Cl, denoted as Pd-P/Cl, bonds. This
strong peak was similarly observed in the case of other
supported Pd complexes, such as MS/PP-Pd and SiO2/NEt2/PP-
Pd, as shown in Figure S11 in SI. Table 1 summarizes the
results of the curve-fitting analysis using the Pd-P/Cl parameter
Scheme 1. Preparation of MS/PP-Pd and MS/NEt2/PP-Pd.
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10.1002/cctc.201700439
ChemCatChem
COMMUNICATION
along with the data of PdCl2(PPh3)2 crystal structure.[31] The
peaks for supported Pd complexes were well fitted, with a
coordination number (N) of approximately 3 and Pd-P/Cl bond
length (r) of 2.26 Å. These results clearly indicated that the Pd
complex structure was maintained after immobilization on the
support. Larger Debye-Waller factor (∆σ2) value of
MS(C12)/NEt2/PP-Pd compared with MS(C12)/PP-Pd suggests
the steric effect of the tertiary amine group on the Pd complex
co-immobilized on the same solid surface. From these
characterization results of the elemental analysis, NMR, and
XAFS, the proposed structure of MS/NEt2/PP-Pd is shown in
Scheme 1.
substrate/catalyst ratio was increased from 256 (Table 2) to
1000 (Table 3). As shown in Table 3, the catalytic activity
increased with decreasing pore diameter of the MS support.
Moreover, the time course of allylation reactions in Figure S12
also indicate that catalyst performance was enhanced by small
pore size. On the other hand, Pd grafting density did not strongly
affect catalytic activity. These results suggest that pore
curvature is essential for the catalysis,[19] and that “two
dimensional” accumulation of active species cannot strongly
improve the catalytic performance. Catalysts with small pores
(i.e., high pore curvature) showed higher activity than those with
large pores (i.e., low pore curvature), suggesting that “three-
dimensional” accumulation of active species can effectivly
accelerate catalytic reactions.
Table 1. Curve-fitting analysis of EXAFS spectra for PP-Pd complexes.[a]
Table 2. The allylation catalyzed by SiO2-supported Pd complexes [a]
r [c]
∆σ2 [d]
[Å2×10–3
∆E [e]
Rf [f]
[%]
Sample
Shell
N [b]
[Å]
]
[eV]
MS(C12)/NEt2/P
P-Pd
2.7
±0.4
2.9
±0.4
3.0
±0.5
2.1
±0.3
3.0
(fix)
2
2.25
4.86
–8.65
±2.12
–3.29
±2.09
–5.14
±2.09
–12.8
±2.22
–5.89
±1.91
Pd-P/Cl
Pd-P/Cl
Pd-P/Cl
Pd-P/Cl
Pd-P/Cl
0.086
0.142
0.057
0.592
1.28
±0.01
2.27
±0.23
2.80
MS(C12)/PP-Pd
Catalyst
Pore size of MS
support [nm] [b]
Conv
. [%]
Yield
TON
[Pd-1]
±0.01
2.26
±0.23
5.43
(mono/di)
[%]
SiO2/NEt2/PP-
Pd
[c]
±0.01
2.26
±0.23
4.68
SiO2/PP-Pd
-
38
62
68
98
99
99
98
72
35 / 3
110
190
220
490
470
460
470
210
MS(C12)/NEt2/P
P-Pd (used)
PP-Pd
MS(C12)/PP-Pd
2.3
-
49 / 12
51 / 17
6 / 93
±0.01
2.29
±0.23
2.64
SiO2/NEt2/PP-Pd
(THF solution) [g]
±0.01
2.34[j]
2.30[j]
±0.03
MS(C8)/NEt2/PP-Pd
MS(C10)/NEt2/PP-Pd
MS(C12)/NEt2/PP-Pd
MS(C18)/NEt2/PP-Pd
SBA-16/NEt2/PP-Pd
1.6
1.9
2.3
3.1
5.3
17 / 83
18 / 80
11 / 86
54 / 14
Pd(II)Cl2(PPh3)2
[i]
(Pd-P)
(Pd-Cl)
2
[a] Fourier transform and Fourier-filtering regions were limited, where ∆k = 2.8
~ 15 Å-1. and ∆r = 1.4 ~ 2.2 Å, respectively. [b] Coordination number. [c] Bond
distance between absorber and backscatter atoms. [d] The Debye-Waller
factor (DW), which is relative to the DW of the reference. [e] The inner
potential correction accounts for the difference in the inner potential between
the sample and reference. [f] The goodness of curve fit. [g] Homogeneous
THF solution of the PP-Pd complex. [i] Data from ref. [21] [j] Average value
was reported.
[a] Reaction conditions: ethyl acetoacetate (1.0 mmol), allylmethylcarbonate
(2.5 equiv. to ketoester), Pd catalyst (Pd: 3.9 μmol), K2CO3 (0.50 mmol),
toluene (2 mL), 70 oC, 60 min. [b] Determined by BJH method. [c] TON was
calculated as follows: TON = (moles of nucleophile)×[(yield of the mono-
product) + 2×(yield of the di-product)] / (moles of Pd).
Allylation of ethyl acetoacetate with allylmethylcarbonate was
carried out by using Pd complex catalysts. The results are
summarized in Table 2. MS(C12)/PP-Pd showed slightly higher
activity (TON=190) than SiO2/PP-Pd (TON=110). Surprisingly,
the catalytic performances of MS supported catalysts were
significantly enhanced by the co-immobilization of the tertiary
amine group on the same support surface: MS(C12)/NEt2/PP-Pd
showed TON value of 460. This value is much higher than that
of the nonporous catalyst with both Pd complexes and tertiary
amines (SiO2/NEt2/PP-Pd: TON=220). The TON value of the
tertiary amine-Pd complex catalysts (MS(C8~18)/NEt2/PP-Pd)
with MS support synthesized with primary amine template was
more than 460 for the pore diameter range of 1.6-3.1 nm,
however, this value suddenly dropped to the value of the
nonporous support when the pore size increased to more than
5.3 nm (TON=210).
Table 3. Effect of pore size and Pd grafting density on the initial TOF of the
allylation reaction
Catalyst
Pore size of MS
support [nm] [a]
Pd grafting
density
[μmol m-2][b]
0.15
Initial
TOF [Pd-1
h-1] [c]
1240
890
MS(C8)/NEt2/PP-Pd
MS(C12)/NEt2/PP-Pd
MS(C18)/NEt2/PP-Pd
SBA-16/NEt2/PP-Pd
SiO2/NEt2/PP-Pd
1.6
2.3
3.1
5.3
-
0.33
0.22
610
0.33
240
220[d]
0.57
[a] Determined by BJH method. [b] Calculated as follows: (Pd grafting density)
= (Pd loading [μmol g-1])/(Surface area [m2 g-1]). [c] Reaction conditions: ethyl
acetoacetate (1.0 mmol), allylmethylcarbonate (2.5 mmol), MS/NEt2/PP-Pd
(Pd: 1.0 μmol), K2CO3 (0.17 mmol), toluene (4 mL), 70 oC. The initial TOF was
calculated from the TON value at 1 h. [d] Reaction conditions of Table 2.
The Pd-catalyzed allylation is usually started by the reaction
between a Pd(0) species and an allylating agent to form π-
allylpalladium which undergoes addition of a nucleophile. In our
case, in-situ formation of Pd(0) complex by the removal of
chlorine from the PP-Pd(η1-allyl)Cl complex by the reaction with
ethyl acetoacetate was proposed (Scheme S1 in SI).[10] After the
Table 3 summerized effect of pore size and Pd grafting
density on the initial turnober frequency (TOF) of the allylation
reaction. Pd grafting density was calculated from Pd loading
(μmol g-1) and the surface area of MS support (m2 g-1). To
determine the initial TOF of each MS-supported catalyst, the
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10.1002/cctc.201700439
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allylation, the solid catalyst MS(C12)/NEt2/PP-Pd was recovered
and the XAFS measurement was conducted. As shown in Table
1, N value decreased to 2.1 in the used MS(C12)/NEt2/PP-Pd.
This result supports (i) the activation process, removal of
chlorine from Pd center, as mentioned above and (ii) easy
access of substrate molecules to almost all of the Pd complexes
located inside the mesopore. After the formation of active Pd(0)
species, successive reactions with the allylating agent formed π-
allylpalladium (Figure 3A). During the catalytic cycle, the tertiary
amine group, which is close to the Pd complex, simultaneously
activates the nucleophile to accelerate the allylation reaction
(Figure 3A).
in SI), nonporous SiO2 was not good support for the reaction
(TON=24), indicating that mesoporous structure is effective for
the concerted activation of allylic alcohol. Interestingly, the
immobilization of PP-Pd on the MS support enhanced its
performance nine times the value of homogeneous PP-Pd
(TON=10). The MS(C12)/PP-Pd-catalyzed allylation with allylic
alcohol successfully proceeded with only 0.1 mol% of Pd: the
TON value of MS(C12)/PP-Pd was up to 820 under solvent free
conditions (Scheme 2C). In the case of the reaction with allylic
alcohol, the MS(C8)/PP-Pd catalyst with small pores showed
performance similar to that of the MS(C12)/PP-Pd. The effect of
pore size on the above reaction with allylic alcohol is currently
investigated.
Figure 3. (A) Basic and (B) acidic acceleration of the allylation reaction using
allylmethylcarbonate and allyl alcohol, respectively.
To examine the stability of the catalyst, the substrate/catalyst
ratio was increased. The reaction of 15 mmol of the ketoester
smoothly proceeded in the presence of 0.5 μmol of Pd in
MS(C8)/NEt2/PP-Pd with a TON value of up to 22,700 (Scheme
2A). A phenol derivative can also be used as a nucleophile. The
reaction between bisphenol A and allyl acetate resulted in a 98%
yield of double allylated product for 4 h with a total TON of 1,960
(Scheme
2B).
The
product,
4,4'-(propane-2,2-
diyl)bis(allyloxybenzene), is a potentially useful precursor of
bisglycidyl ether, a monomer of epoxy resin,[32,33] therefore, the
allylation of bisphenol A without allyl halide is a highly desirable
chemical process. The product yield and TON of our catalyst
system are much higher than those of the previously reported
non-halogenated systems for double allylation of bisphenol A,
such as [RuCp(PPh3)2]+: yield=51%, TON=260;[33] Pd(OAc)2:
24%, 240;[33] Pd2(dba)3: 98%, 80;[34] Pd/Carbon: 65.8%, 1300,[35]
Scheme 2. High TON allylation with (A) allylmethylcarbonate, (B) allyl acetate,
and (C) allylic alcohol.
or comparable with
the homogeneous Pd(OAc)2 system
reported in a patent (TON=3000).[32]
MS(C12)/PP-Pd
87
Next, the reaction using allylic alcohol instead of carbonate
and acetate was examined using the MS-supported Pd catalyst.
In this case, the catalyst with tertiary amine did not show activity,
whereas, MS with only Pd complex (MS(C12)/PP-Pd) acted as a
good catalyst (TON=87), as shown in Figure 4. Calcination of
68
MS(C12,cal)/PP-Pd
MS(C12)/PP-Pd-cap[a]
31
24
SiO2/PP-Pd
PP-Pd
o
MS(C12) support at 540 C (MS(C12,cal)) before attachment of
10
20
PP-Pd induced decreasing activity (TON=68). The TON value
also decreased by the treatment of the surface Si-OH group by
(MeO)3SiMe before catalytic reaction (TON=31). These results
indicate the participation of the Si-OH group in the catalytic
reaction. Despite the similar density of surface Si-OH (Table S1
0
40
TON / Pd-1
60
80
Figure 4. TON for allylation with allylic alcohol catalyzed by Pd complexes.
Reaction conditions: ethyl acetoacetate (1.0 mmol), allylic alcohol (2.5 equiv.
to ketoester), Pd catalyst (Pd: 6.0 μmol), K2CO3 (0.5 mmol), toluene (4 mL), 70
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10.1002/cctc.201700439
ChemCatChem
COMMUNICATION
oC, 60 min. A small amount of di-substituted product was formed (Table S3) [a]
Si-OH group was treated with (MeO)3SiMe.
Toshihide Baba (Tokyo Institute of Technology) for his generous
support and unrestricted access to analytical facilities.
Keywords: mesoporous silica • palladium • concerted catalysis •
supported catalyst • allylation
In order to determine the interaction between allylic alcohol
and MS surface, 13C CP/MAS NMR measurement of allylic
alcohol adsorbed on MS was conducted. As shown in Figure 5,
new broad signals (C1’ and C3’) could be observed. In the case
of allylic alcohol adsorbed on H-ZSM-5, the C1’ signal shifted
from 64 to 71 ppm (Δδ=4 ppm).[36] The C1’ signal on MS also
showed a downfield shift with a smaller Δδ value (1.5 ppm)
suggesting a weak acidic interaction between the hydroxyl group
of allylic alcohol and Si-OH to accelerate the π-allylpalladium
formation (Figure 3B).
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In summary, this study demonstrated the concerted catalysis
between the Pd complex and tertiary amine/silanol in
mesoporous
silica.
The
reactions
using
allylmethylcarbonate/allylacetate were effectively accelerated by
tertiary amine immobilized into the same mesopore with the Pd
complex. The catalytic activity strongly depended on the pore
diameter: a tight space was more effective than a relatively large
pore. Allylic alcohol, a tough allylating agent, was activated by a
Si-OH group on the MS surface, resulting in a higher catalytic
performance of MS/PP-Pd compared with the homogeneous Pd
complex. The precise control of the support morphology is a
high-potential approach for the enhancement of the concerted
catalysis on the surface.
Q. Zhao, Y. Zhu, Z. Sun, Y. Li, G. Zhang, F. Zhang, X. Fan, J. Mater.
Chem. A 2015, 3, 2609.
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XAFS measurements were conducted under the approval of the
Photon Factory Advisory Committee (Proposal no. 2016G025).
This study was supported by the JSPS KAKENHI (Grant no.
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Research on Innovative Areas (Grant no. 16H01010 and
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This article is protected by copyright. All rights reserved.

10.1002/cctc.201700439
ChemCatChem
COMMUNICATION
Entry for the Table of Contents
COMMUNICATION
Concerted catalysis between the Pd
complex and tertiary amine/silanol in
mesoporous silica enables highly
efficient allylation of nucleophiles with
allyl methyl carbonate, allyl acetate,
and also allylic alcohol.
Ken Motokura*, Marika Ikeda, Masayuki
Nambo, Wang-Jae Chun, Kiyotaka
Nakajima, and Shinji Tanaka
“Three-Dimensional” Accumulation
in Mesopore
Page No. – Page No.
Concerted Catalysis in Tight Spaces:
Palladium-Catalyzed Allylation
Reactions Accelerated by
Accumulated Active Sites in
Mesoporous Silica
Nu-H
Mesoporous support
This article is protected by copyright. All rights reserved.