Highly efficient mesoporous polymer supported phosphine-gold(i) complex catalysts for amination of allylic alcohols and intramolecular cyclization reactions

Article abstract of DOI:10.1039/c7ra12498h

A series of novel heterogeneous gold(i) catalysts were synthesized by immobilizing gold(i) complexes on ordered mesoporous polymer FDU-15 and characterized by XRD, N₂ adsorption-desorption, FT-IR, TEM, EDS, etc. The catalytic activities of thes

Full text of DOI:10.1039/c7ra12498h

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Highly efficient mesoporous polymer supported
phosphine-gold(I) complex catalysts for amination
of allylic alcohols and intramolecular cyclization
reactions†
Cite this: RSC Adv., 2018, 8, 1737
*
*
Huoliang Gu,‡ Xiong Sun,‡ Yong Wang, Haihong Wu
and Peng Wu
A series of novel heterogeneous gold(I) catalysts were synthesized by immobilizing gold(I) complexes on
ordered mesoporous polymer FDU-15 and characterized by XRD, N2 adsorption–desorption, FT-IR, TEM,
EDS, etc. The catalytic activities of these catalysts were evaluated by the amination reactions of allylic
alcohols. Among the catalysts investigated, FDU-(p-CF3Ph)2PAuCl (3d) was identified as the most
efficient catalyst. Compared to the homogeneous catalyst, the enhanced catalytic activity of the
heterogeneous gold(I) catalyst is closely related to the mesoporous structure of FDU-15. The catalytic
system was suitable for a broad range of substrates and can be easily recovered and recycled at least
twelve times without significant loss of catalytic activity. In addition, the catalytic performance of 3d was
further examined for intramolecular cyclization for the synthesis of heterocyclic compounds.
Received 16th November 2017
Accepted 18th December 2017
DOI: 10.1039/c7ra12498h
rsc.li/rsc-advances
a
polystyrene-immobilized gold(I) complex, which shows
1. Introduction
remarkable catalytic activities in three model transformations.
Toste et al.23 have developed silica-supported cationic gold(I)
complexes, which exhibit superior reactivity in intramolecular
additions of allenes with alkynes. Cai et al.24 have developed an
efficient and easily recoverable magnetic nanoparticle sup-
ported gold(I) catalyst for the direct reductive amination reac-
tion, which proceeded at room temperature. Very recently, Shi
et al.25 reported a PS-TA-Au(I) catalyst with good activity and
chemoselectivity. Asensio et al.26 developed silica-immobilized
NHC-gold(I) complexes, which are efficient in hydration and
cyclization. In our previous study, we have successfully immo-
bilized a chiral gold catalyst and applied it for the asymmetric
cycloaddition of 2-alkynyl-2-alken-1-ones with nitrones.27
Despite these signicant advances, the design and development
The great potential of homogeneous gold(I) complex catalysts
for chemical transformations has attracted increasing interest
in numerous elds of research.1–6 In this context, numerous
homogeneous gold(I) complex-catalyzed reactions have been
explored for the construction of carbon–carbon or carbon–
heteroatom bonds, which are prevalent in many important
pharmaceutical and bioactive natural products.7–13 However,
homogeneous catalysts oen suffer from several drawbacks
related to the handling of sensitive metal–ligand complexes,
deactivation during reaction and difficulty in recovery and reuse
of expensive reagents, which hinders their practical applica-
tions in industrial processes. One of the most promising
approaches to overcome these drawbacks is to generate
heterogeneous gold(I) catalysts.14–20
of
a new heterogeneous gold(I) catalyst system is still
challenging.
The use of heterogeneous catalysts has multiple advantages
in both industrial and environmental concerns. Various types of
materials, such as mesoporous silica and amorphous polymer,
have been employed to support the gold(I) catalysts. Corma
et al.21 have immobilized a gold–carbene complex on meso-
structured silicates and applied them for the hydrogenation of
alkenes and the Suzuki reaction. Yu et al.22 have described
The nature of support plays an important role in governing
the catalytic activities of supported gold(I) species on it. The
mesoporous material has a suitable pore size for easy func-
tionalization, particularly with large molecules, such as phos-
phine linkers and long-chain alkyl alkoxysiloxanes. Moreover,
the ordered mesopores with a larger specic surface area can
enable uniform distribution of anchored functional groups and
benet to mass transfer. The discovery of a class of mesoporous
resol resin, which is purely an organic framework, opens up new
opportunities for the synthesis of novel heterogeneous gold(I)
catalysts. In comparison to conventional silica-based MCM-41,
SBA-15 and organic–inorganic hybrid mesoporous materials,
this ordered mesopolymer shares the advantages of both
Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of
Chemistry and Molecular Engineering, East China Normal University, North
Zhongshan Rd. 3663, Shanghai, 200062, China. E-mail: hhwu@chem.ecnu.edu.cn;
pwu@chem.ecnu.edu.cn; Fax: +86-21-6223-8510
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c7ra12498h
‡ These authors contributed equally to this work.
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mesostructures and conventional organic polymers.28,29 Its mixture was stirred at r.t. for 8 h. The resultant solution was
uniform mesopores with strong hydrophobicity allow for the mixed with FDU-CH2Cl (1 g) and stirred overnight at r.t. to
easy access of organic reactants to the active sites within the obtain FDU-PPh2. Following this, FDU-PPh2 (1.5 g) was mixed
channels. Based on this concept, we have succeeded in creating with Me2SAuCl (0.14 mmol) in THF (10 mL) under argon
several heterogeneous catalysts, which show good catalytic atmosphere, and stirred at r.t. overnight to obtain the catalysts,
activities in some chemical transformations.30–35 Herein, we which were denoted as FDU-Ph2PAuCl, FDU-(o-OMePh)2PAuCl
further explored the performance of FDU-type mesopolymer as and FDU-(p-OMePh)2PAuCl (3a–3c). The Au loadings were
the support for homogeneous gold(I) catalysts. We synthesized determined by inductively coupled plasma atomic emission
a series of new supported gold(I) catalysts and studied their spectroscopy (ICP-AES).
catalytic activities in amination of allylic alcohols36 and intra-
molecular cyclization.37,38 These reactions were chosen because
of their high atomic-efficiency and the heterocyclic products are
2.4 The preparation of catalyst 3d
structural fragments, which are widely found in many phar- (p-CF3Ph)2PCl (7 mmol) was mixed with metal Li (14 mmol) in
maceutical active compounds.
anhydrous THF (20 mL) under argon atmosphere at ꢀ5 ꢁC; the
mixture was stirred at r.t. for 1 h. The resultant solution was
mixed with FDU-CH2Cl (1 g) and stirred 10 h at 40 ꢁC to obtain
a ligand-functionalized material, FDU-(p-CF3Ph)2P. Following
this, FDU-(p-CF3Ph)2P (0.5 g) was mixed with Me2SAuCl (0.15 g)
in anhydrous THF (15 mL) under argon atmosphere, and stirred
at r.t. overnight to obtain the catalyst, which was denoted as
FDU-(p-CF3Ph)2PAuCl (3d).
2. Experimental
2.1 General
All reactions were carried out under an atmosphere of Ar in
ame-dried glassware with magnetic stirring. H NMR spectra
1
and 13C NMR spectra were recorded on a Bruker 500 MHz
spectrometer in DMSO-d6 or CDCl3. All signals are reported
in ppm with the internal TMS signal at 0 ppm as a standard.
Data for 1H NMR spectra are reported as follows: chemical shi
(ppm, referenced to TMS; s ¼ singlet, d ¼ doublet, t ¼ triplet, dd
¼ doublet of doublets, m ¼ multiplet), coupling constant (Hz),
and integration. Data for 13C NMR are reported in terms of
chemical shi (ppm) relative to residual solvent peak (CDCl3:
77.0 ppm). Reactions were monitored by thin layer chroma-
tography (TLC) using silica gel plates. Flash column chroma-
tography was performed over silica gel (200–300 mesh).
Dichloromethane and toluene were freshly distilled from CaH2;
THF and dioxane were freshly distilled from sodium metal prior
to use. The X-ray diffraction (XRD) patterns were collected on
a Bruker D8 ADVANCE instrument using Cu-Ka radiation (l ¼
2.5 General procedure for amination of allylic alcohols and
reused of the catalyst
Under argon atmosphere, a mixture of catalyst 3d (6.9 mg,
0.05 mol%) and AgOTf (0.13 mg, 0.05 mol%) in dry solvent (1
mL) was magnetically stirred for 10 min at room temperature. A
solution of allylic alcohols 4 (1 mmol) and amine 5 (2 mmol) in
dry solvent (1 mL) was added into the aforementioned
suspension and stirred under argon atmosphere. The reaction
was monitored by TLC. When the reaction was over, the catalyst
was recovered by simple ltration. The ltrate was diluted with
water and brine; the product was extracted with ethyl acetate (3
ꢂ 10 mL). The combined organic phase was dried over anhy-
drous MgSO4 and concentrated under vacuum. The residue was
puried by column chromatography on silica gel affording the
product 6. The catalyst was washed with ethyl acetate and water
and then suspended in acetone for 30 min under ultra-
sonication. Then, the catalyst was ltered, dried at 50 ꢁC under
vacuum overnight and reused for the next cycle.
˚
1.5418 A) at 35 kV and 30 mA. Nitrogen adsorption–desorption
isotherms were measured on a Quantachrome Autosorb-3B
instrument aer evacuating the samples at 423 K for 6 h. The
specic surface areas were evaluated using the Brunauer–
Emmett–Teller (BET) method and the pore distribution was
calculated by the BJH method from adsorption branches of
isotherms. The TEM images were recorded using a JEOL-JEM-
2010 microscope aer the specimens were dispersed in
ethanol and placed on holed-copper grids. The Au loading was
determined by inductively coupled plasma-atomic emission
spectroscopy (ICP-AES).
2.6 General procedure for the preparation of 2,3-dihydro-4H-
pyran-4-ones
Under an argon atmosphere, AgOTf (5.8 mg, 5 mol%) was added
into a suspension of 3d (316.5 mg, 5 mol%) in 4 mL toluene at
room temperature. The mixture was stirred for 10 min to
generate the cationic gold catalyst. Aer the substrate 7 (0.45
mmol) was added, the reaction mixture was stirred at room
temperature. The reaction was monitored by TLC. When the
reaction was over, the catalyst was recovered by simple ltra-
tion. The ltrate was diluted with brine, and the product was
extracted with ethyl acetate. The combined organic phase was
dried over anhydrous MgSO4 and concentrated under vacuum.
2.2 Preparation of FDU-type mesopolymer and FDU-CH2Cl
The FDU-type mesopolymer was prepared according to previ-
ously reported procedures.28 Then, FDU-type material was
chloromethylated with chloromethyl methyl ether to obtain
FDU-CH2Cl using AlCl3 as a catalyst.34
2.3 Typical methods for preparation of catalysts 3a–3c
Ar2PCl (7 mmol) was mixed with Li metal (14 mmol) in anhy- The residue was puried by column chromatography on silica
drous THF (20 mL) under argon atmosphere at ꢀ5 ꢁC; the gel affording the product 8a–k.
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2.7 Synthesis of substituted furan catalyzed by 3d
AgOTf (0.1 mol%) was added to a solution of 3d (0.1 mol%) in
dry toluene at room temperature under an argon atmosphere.
The mixture was stirred for 10 min to generate the gold(I)
catalyst. Aer the substrate 9 was added, the reaction mixture
was further stirred at room temperature. The reaction was
monitored by TLC. When the reaction was completed, the
catalyst was recovered by simple ltration. The ltrate was
diluted with water and brine, and the product was extracted
with ethyl acetate. The combined organic phase was dried over
anhydrous MgSO4 and concentrated under vacuum. The
residue was puried by column chromatography on silica gel to
afford the product 10.
Fig. 1 Powder XRD patterns of (a) FDU-15, (b) 1, (c) 2d and (d) 3d.
3. Results and discussion
3.1 Synthesis and characterization of catalysts
area (SBET), pore diameter (Dp) and pore volume (Vp) were
calculated using the BJH method from the desorption branches
of the N2 isotherm (Table 1). Aer post-modication, a gradual
decrease in the BET surface areas, pore volume and average
pore diameter was noted, presumably attributed to the incor-
poration of the organic groups (phosphine ligand) into the
channels of FDU-type mesopolymer.
Transmission electron microscopy (TEM) images (Fig. 3)
displayed highly ordered mesoporous arrays and long-range
mesoporous channels for the parent and functionalized meso-
polymers. The mesopore array of 3d was a typical 2D hexagonal
mesostructure, which veried that well-ordered mesoporous
structures were maintained precisely aer the gradual chemical
graing.
The samples before and aer graing were further charac-
terized by FT-IR (Fig. S3†). The band at 3437 cmꢀ1 is assigned to
the phenolic hydroxyl stretching vibration. Comparing 1 with the
parent FDU-type material, a new band appeared at 698 cmꢀ1 aer
chloromethylation treatment, which is attributed to the stretch-
ing vibration of the C–Cl bond.35 For sample 2d, the new bands
developed at 1065 cmꢀ1 and 1167 cmꢀ1 are assigned to the C–F
bond stretching vibration. The band at 1323 cmꢀ1 is assigned to
the characteristic P-C vibration. These results demonstrated that
the phosphine ligands were successfully introduced in the mes-
oporous polymers. No visible change was observed in IR spectra
aer further modication with Me2SAuCl.
The strategy for the synthesis of FDU-type mesopolymer sup-
ported gold(I) catalysts 3a–3d are shown in Scheme 1. The
chloromethylated materials, FDU-CH2Cl (1), were rst prepared
by anchoring the –CH2Cl groups to the benzene rings of the
mesopolymers using AlCl3 and then functionalizing with
phosphine ligands to afford ligand-modied materials 2a–2d.
When 2a–2d were subsequently stirred in anhydrous THF
solution containing gold precursor under argon atmosphere,
the gold(I) ions were coordinated to phosphine ligands to afford
the catalysts 3a–3d.
The powder X-ray diffraction (XRD) patterns of FDU-15
mesopolymer and the modied mesoporous materials are
shown in Fig. 1 and S1 (ESI†). Although the diffraction peaks
gradually decreased in intensity aer stepwise modications,
all samples still showed well dened (10), (11), (20) planes of
a 2D hexagonal structure (P6mm) for the FDU-15 mesopolymer,
which proved that the mesostructures were well preserved in the
entire process of catalyst preparation.
Fig. 2 and S2† show the N2 adsorption–desorption isotherms
and the corresponding pore size distributions of the parent and
graed FDU-15 samples. All samples displayed a typical type IV
isotherm with apparent H2 hysteresis loops, implying that the
samples possessed a mesoporous structure. The specic surface
In addition, the samples before and aer functionalization
were characterized by EDS spectroscopy (Fig. S4†) and solid
Scheme 1 The strategy for the synthesis FDU-type mesopolymer Fig. 2 The nitrogen adsorption–desorption isotherms and BJH pore
supported gold(I) catalysts 3a–3d.
size distribution curves of FDU-15, 1, 2d and 3d.
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Table 1 Textural properties of parent FDU-15 and grafted samplesa
environment-friendly process since it generates water as the
only by-product. The results summarized in Table 2 show the
inuence of the reaction parameters.
Sample
SBET (m2 gꢀ1
)
Vp (cm3 gꢀ1
)
Dpb (nm)
Auc (wt%)
The homogeneous Ph3PAuCl catalyst (0.5 mol%) afforded
67% product yield (Table 2, entry 1) in dioxane. In contrast, the
immobilized catalyst 3a afforded a 89% yield with 0.1 mol% Au
loading (Table 2, entry 2). Other immobilized catalysts, 3b–d,
also showed excellent yield (Table 2, entries 3–5) though a much
lower catalyst amount was used. In particular, sample 3d could
afford a 95% product yield in 1.5 h. The catalyst bearing
electron-donating group – OMe in phosphine ligand required
a longer reaction time to give a good product yield (Table 2,
entries 3 and 4). When the catalyst amount was decreased to
0.05 mol%, all catalysts showed detrimental activity except for
3d (Table 2, entries 6–9). The high activity of 3d might be due to
the strong electron-withdrawing effect of the –CF3 group in the
phosphine ligand.39–42 Further, decreasing the amount of 3d by
tenfold to 0.01 mol% could still lead to a 50% yield aer reac-
tion for 8 h (Table 2, entry 10). Thus, 3d was chosen for the
subsequent study due to its high catalytic activity. The solvent-
effect on the reaction was also studied (Table 2, entries 11–15).
Among several commonly used solvents, the reaction
proceeding in dioxane afforded the best yield. When homoge-
neous gold was supported on polystyrene43 and SBA-15,44,45 both
catalysts showed lower activity than FDU-15 supported catalysts
(Table 2, entries 16 and 17). No reaction was observed on using
AgOTf as the catalyst. Interestingly, AgOTf could afford 29%
product yield under dark condition (Table 2, entry 18), which is
probably due to the light-sensitive nature of AgOTf.46 This light-
dependent activity was also observed for homogeneous
FDU-15
1
2a
2b
2c
2d
3a
3b
3c
466
443
421
405
417
432
417
383
397
400
0.47
0.43
0.41
0.40
0.40
0.30
0.40
0.30
0.40
0.30
3.3
3.3
3.2
3.3
3.3
3.3
3.2
3.3
3.3
3.3
—
—
—
—
—
—
2.6
0.98
1.0
1.4
3d
a
Given by N2 sorption at 77 K. b By BJH analysis. c ICP analysis.
state 13C NMR spectroscopy (Fig. S5†). The characteristic peak
of elemental Cl was observed aer chloromethylation
(Fig. S4b†). Aer the functionalization with chemical ligand and
homogeneous gold catalyst, new characteristic peaks of
elemental F and Au were noticed (Fig. S4c–d†). According to the
13C NMR spectra, all samples show distinct signals at 35, 129
and 151 ppm, which are assigned to the methylene bridges,
phenolic hydroxyl substitutions and other carbons in the
phenol ring, respectively. Compared to FDU-15, the ligand-
functionalized sample displayed a new band at 65 ppm, which
corresponds to the methylene bridges between the phenol rings
and ligands. The signals of the carbons in –CF3 groups are not
visible, which may overlap with the other carbon in the phenol
ring. These spectra further conrmed the successful function-
alization of FDU-CH2Cl with the ligand and the homogeneous
gold catalyst. Moreover, the binding energy at 85.1 eV of Au XPS
spectrum (Fig. S6†) for fresh catalyst-3d clearly conrms the
presence of Au(I) species. The Au loadings were determined to
be 2.6, 0.98, 1.0, 1.4 wt% for catalysts 3a, 3b, 3c, 3d, respectively
(Table 1).
Table 2 Screening of catalysts and reaction conditions for amination
of allylic alcoholsa
Au amount
(mol%)
Entry Catalyst
Solvent
Time (h) Yieldb (%)
3.2 Catalytic activity
1
2
3
4
5
6
7
8
Ph3PAuCl
3a
3b
3c
3d
3a
3b
3c
3d
3d
3d
3d
3d
3d
3d
0.5
0.1
0.1
0.1
Dioxane 1.5
Dioxane 1.5
67 (85)c
89
90
90
95
43
38
41
91
50
50
75
Trace
n.r.
n.r.
73
To evaluate the catalytic activities of FDU-supported gold(I)
catalysts, the amination of trans-1,3-diphenyl-2-propen-1-ol
with p-toluene sulphonamide was studied as a model reac-
tion. Meeting atom economy demand, this reaction is an
Dioxane
Dioxane
4
4
0.1
Dioxane 1.5
Dioxane
0.05
0.05
0.05
0.05
0.01
0.05
0.05
0.05
0.05
0.05
7
Dioxane 20
Dioxane 20
Dioxane 1.5
9
10
11
12
13
14
15
16
17
18
19
Dioxane
MeCN
MeNO2
THF
8
1.5
3
3
DMF
3
DMSO
3
SBA-PPh2AuCl 0.5
PS-PPh2AuCl
AgOTf
Dioxane 1.5
Dioxane 1.5
Dioxane 1.5
Dioxane 24
0.5
0.1
0.1
78
n.r (29)c
n.r
2d
a
Reaction conditions:
1
mmol trans-1,3-diphenyl-2-propen-1-ol,
2 mmol p-toluene sulfonamide, 1 : 1 cat. (mol% Au)/AgOTf, 2 mL
b
c
solvent, argon atmosphere. Isolated yield. Data in parentheses
were yields avoiding light.
Fig. 3 TEM images of (a) FDU-15, (b) 1 (FDU-CH2Cl), (c) 2d and (d) 3d.
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Ph3PAuCl, which also provises better reactivity under dark these reactions proceeded at a lower rate than that of 4a and
conditions (Table 2, entry 2). This behavior effectively explains resulted in moderate product yields at higher temperatures. The
the enhanced activity of immobilized catalysts compared with results show that 4b afforded a 2 : 1 mixture of the a- and g-
the homogenous counterpart since the mesoporous wall may substituted allylic sulfonamides at 51% overall yield (Table 3,
protect both AgOTf and Au-catalyst from light-driven decom- entry 9). The reaction of 5b also gave a mixture of the a- and g-
position. This detrimental effect could be prevented by the substituted products (Table 3, entry 10). The g-products may be
mesoporous wall of FDU-15, allowing for the formation of active obtained via hydroamination reaction of the C–C double bond
species Ph3PAuOTf.47 It should be noted that no reaction was pathways.48
observed for sample 2d, which did not contain any Au (Table 2,
The recyclability of catalyst 3d was also examined in the
entry 19), further emphasizing the catalytic role of Au(I) centers. amination reaction of trans-1,3-diphenyl-2-propen-1-ol with p-
Under the optimized reaction conditions, we then investi- toluenesulfonamide. The catalyst was recovered by simple
gated the reactivity of different allylic alcohols and amine. The ltration aer reaction, washed with ethyl acetate and acetone
results are summarized in Table 3. Both the electron- and then dried in vacuum. The dried catalysts were directly used
withdrawing and electron-donating substituted aryl sulfon- for the next catalytic cycle. As shown in Fig. 4, catalyst 3d could
amides afforded the desired products in moderate to high yields be reused for at least twelve times without signicant decrease
(Table 3, entries 1–4). However, the use of electron-withdrawing in the isolated yield. We compared catalyst 3d before and aer
groups required longer reaction times and higher temperatures. 12 runs with different characterization in XPS, XRD and BET
Aliphatic sulfonamide and benzyl carbamate also gave excellent (Fig. S6–S8†). It can be clearly observed that the oxidation state
yields (Table 3, entries 5 and 6). Even reactions starting with p- of Au(I) was well retained for the spent catalyst (Fig. S6†).49 The
NO2 and p-Cl substituted-aniline could proceed smoothly, XRD pattern indicated that the ordered structure of organic
affording the corresponding products with a high yield aer frameworks collapsed to some extent aer these runs (Fig. S7†).
a prolonged reaction time (Table 3, entries 7 and 8). Next, we The BET result also indicated that the pore size and specic
investigated the scope of different allylic alcohols (4b–4d) using surface area decreased, in line with the collapse of the
5a or 5b as the coupling partner in most cases (entries 9–14). All
Table 3 Reaction scope of different allylic alcohols and aminea
Entry
Allylic alcohols
Nucleophine
T (ꢁC)
Time (h)
Product
Yieldb (%)
1
30
30
30
50
1.5
4
6a
6b
6c
6d
91
91
81
77
2
4a
4a
4a
3
1.5
26
4c
5
4a
4a
CH3SO2NH2 5e
CbzNH2 5f
50
30
7.5
2
6e
6f
86
98
6c
7c
4a
4a
50
26
6g
93
8
30
85
85
12
53
53
6h
98
9
5a
5b
5a
5b
6i, 6i0
6j, 6j0
51 (2 : 1)d
48 (3 : 1)d
10
4b
4c
11
12
50
50
25
25
6k
6l
48
42
13
5a
5b
50
50
8
9
6m
6n
56
70
14
4d
a
Reaction conditions: 1 mmol allylic alcohols, 2 mmol nucleophile, 3d (0.05 mol% Au), 0.05 mol% AgOTf, 2 mL dioxane, argon atmosphere.
Isolated yield. c 0.2 mol% 3d, 0.2 mol% AgOTf. d The ratio of a-product to g-product.
b
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Scheme 2 The intramolecular cyclization of 9 to 10.
corresponding products in high yield (Table 4, entries 5, 9 and
10). The reactions were also carried out using the substrates
with substituted groups on the other positions of the aryl ring
(Table 4, entries 3, 4, 7 and 8). The aryl ring containing a chloro
group at the meta position afforded a higher yield than those at
the para and meta positions (Table 4, entries 6–8), while the
methoxyl group led to a slightly lower yield (Table 4, entries 2–
4). The catalyst can also be easily recycled.
Fig. 4 The reusability of sample 3d in the amination reaction of trans-
1,3-diphenyl-2-propen-1-ol with p-toluenesulfonamide.
Finally, we used 3d as the catalyst for the synthesis of ve-
membered heterocyclic compounds. Furans are important
intermediates, which widely serve as key structural subunits in
numerous natural products, industrial organic syntheses and
material science.61–63 The reaction of propargyl alcohol 9 affor-
ded the corresponding substituted furan 10 at 92% yield aer
6 h, which shows similar activity to the homogeneous catalyst
(Scheme 2).
framework, which is probably responsible for the sharp
decrease of product yield aer twelve runs.
We further examined the utility of 3d in the intramolecular
cyclization for the synthesis of substituted 2,3-dihydro-4H-
pyran-4-ones. The dihydropyranones moiety as one of the most
important components has been observed in many naturally
occurring products and displays a variety of biological activi-
ties.50–60 Aer preliminary screening of the reaction conditions,
catalyst 3d could efficiently catalyze the intramolecular cycli-
zation of 7a, which provided results comparable to those ob-
tained using homogeneous catalysts (Table 4, entry1). Benzene
ring substituted 2,3-dihydro-4H-pyran-4-ones compounds 8a–k
were also synthesized in good yields using this heterogeneous
catalyst(Table 4).
4. Conclusions
In summary, we have developed a series of ordered mesopol-
ymers FDU supported gold(I) catalysts (3a–3d). Catalyst 3d
showed the best catalytic activity in amination of allylic alcohols
with different nucleophiles. Compared with homogeneous
gold(I) catalyst, the heterogeneous gold(I) catalysts exhibited
enhanced catalytic activity. The present study suggests the
potential structural cooperation of the support material could
enhance the stability. Moreover, the reaction also performed
efficiently at a lower catalyst loading (0.05 mol%), which may be
explained by the high dispersion of active sites in the meso-
polymers and the catalysts can be easily recovered and recycled
without signicant decrease in activity. Catalyst 3d was also
applicable to other organic transformations, affording good
yields. Further research for application of 3d and other
heterogeneous gold catalysts are now in progress.
The reaction of substituted groups at the para position of the
aryl ring proceeded efficiently (Table 4, entries 2, 5, 6, 9, 10 and
11). The reactions of substrates comprising strong electron-
withdrawing groups such as –CF3, –NO2 and –CN all gave the
Table 4 The intramolecular cyclization of 7a–7ka
Conflicts of interest
Entry
R
Product
Time (h)
Yieldb (%)
There are no conicts to declare.
1
2
3
4
5
6
7
8
H 7a
8a
8b
8c
8d
8e
8f
8g
8h
8i
8
81
80
72
73
84
56
80
58
90
83
78
Acknowledgements
4-OCH3 7b
3-OCH3 7c
2-OCH3 7d
4-CF3 7e
4-Cl 7f
3-Cl 7g
2-Cl 7h
4-CN 7i
4-NO2 7j
4-Br 7k
12
12
12
48
12
24
12
24
24
12
We acknowledge the nancial support by NSFC (21373088,
21533002), China Ministry of Science and Technology
(2016YFA0202804).
9
10
11
References
8j
8k
1 A. Hoffmann-Roder and N. Krause, Org. Biomol. Chem., 2005,
3, 387–391.
2 G. J. Hutchings, Catal. Today, 2005, 100, 55–61.
a
Reaction conditions: 0.45 mmol 7; 3d (5 mol% Au), and 5 mol%
b
AgOTf; 4 mL toluene; argon atmosphere. Isolated yield.
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Paper
RSC Advances
3 A. S. K. Hashmi and G. J. Hutchings, Angew. Chem., Int. Ed., 33 R. Xing, H. Wu, X. Li, Z. Zhao, Y. Liu, L. Chen and P. Wu, J.
2006, 45, 7896–7936. Mater. Chem., 2009, 19, 4004–4011.
4 A. Stephen and K. Hashmi, Chem. Rev., 2007, 107, 3180–3211. 34 C. Yao, H. Li, H. Wu, Y. Liu and P. Wu, Catal. Commun., 2009,
5 Z. Li, C. Brouwer and C. He, Chem. Rev., 2008, 108, 3239–
10, 1099–1102.
3265.
35 W. Zhang, Q. Wang, H. Wu, P. Wu and M. He, Green Chem.,
2014, 16, 4767–4774.
6 N. Marion and S. P. Nolan, Chem. Soc. Rev., 2008, 37, 1776–
´
1782.
36 X. Giner, P. Trillo and C. Najera, J. Organomet. Chem., 2011,
7 T. Yao, X. Zhang and R. C. Larock, J. Am. Chem. Soc., 2004,
126, 11164–11165.
8 Y. Liu, F. Song, Z. Song, M. Liu and B. Yan, Org. Lett., 2005, 7,
5409–5412.
696, 357–361.
37 M. Egi, K. Azechi, M. Saneto, K. Shimizu and S. Akai, J. Org.
Chem., 2010, 75, 2123–2126.
38 M. Egi, K. Azechi and S. Akai, Org. Lett., 2009, 11, 5002–5005.
9 M. H. Suhre, M. Reif and S. F. Kirsch, Org. Lett., 2005, 7, 39 J. P. Markham, S. T. Staben and F. D. Toste, J. Am. Chem. Soc.,
3925–3927. 2005, 127, 9708–9709.
10 B. D. Sherry, L. Maus, B. N. Laforteza and F. D. Toste, J. Am. 40 P. Dube and F. D. Toste, J. Am. Chem. Soc., 2006, 128, 12062–
Chem. Soc., 2006, 128, 8132–8133. 12063.
11 G. Zhang, L. Cui, Y. Wang and L. Zhang, J. Am. Chem. Soc., 41 D. J. Gorin, B. D. Sherry and F. D. Toste, Chem. Rev., 2008,
2010, 132, 1474–1475. 108, 3351–3378.
12 H. F. Jonsson, S. Evjen and A. Fiksdahl, J. Am. Chem. Soc., 42 W. Wang, G. B. Hammond and B. Xu, J. Am. Chem. Soc., 2012,
2017, 19, 2202–2205. 134, 5697–5705.
13 M. J. Harper, E. J. Emmett, J. F. Bower and C. A. Russell, J. 43 M. Egi, K. Azechi and S. Akai, Adv. Synth. Catal., 2011, 353,
´
Am. Chem. Soc., 2017, 13, 12386–12389.
14 A. Corma, Chem. Rev., 1997, 97, 2373–2420.
15 C. M. Crudden, D. Allen, M. D. Mikoluk and J. Sun, Chem.
Commun., 2001, 1154–1155.
16 A. M. Liu, K. Hidajat and S. Kawi, J. Mol. Catal. A: Chem.,
2001, 168, 303–306.
287–290.
44 D. Zhao, Q. Huo, J. Feng, B. F. Chmelka and G. D. Stucky, J.
Am. Chem. Soc., 1998, 120, 6024–6036.
45 X. Feng, M. Yan, T. Zhang, Y. Liu, M. Bao and X. Feng, Green
Chem., 2010, 12, 1758–1766.
46 Q. Dong, N. Li, R. Qiu, J. Wang, C. Guo and X. Xu, J.
Organomet. Chem., 2015, 799–800, 122–127.
47 J. Zhang, C.-G. Yang and C. He, J. Am. Chem. Soc., 2006, 128,
1798–1799.
17 D. E. De Vos, M. Dams, B. F. Sels and P. A. Jacobs, Chem. Rev.,
2002, 102, 3615–3640.
¨
18 A. Taguchi and F. Schuth, Microporous Mesoporous Mater.,
2005, 77, 1–45.
48 P. Mukherjee and R. A. Widenhoefer, Org. Lett., 2010, 12,
1184–1187.
19 M. Guino and K. K. Hii, Chem. Soc. Rev., 2007, 36, 608–617.
20 R. A. Sheldon, Chem. Soc. Rev., 2012, 41, 1437–1451.
´
49 E. Aguilo, R. Gavara, J. Carlos Lima, J. Llorca and
´
´
21 A. Corma, E. Gutierrez-Puebla, M. Iglesias, A. Monge,
L. Rodrıguez, J. Mater. Chem. C, 2013, 1, 5538–5547.
´
´
S. Perez-Ferreras and F. Sanchez, Adv. Synth. Catal., 2006, 50 M. M. Faul and B. E. Huff, Chem. Rev., 2000, 100, 2407–2474.
348, 1899–1907.
22 W. Cao and B. Yu, Adv. Synth. Catal., 2011, 353, 1903–1907.
51 C. Yao, Z. Xiao, R. Liu, T. Li, W. Jiao and C. Yu, Chem.–Eur. J.,
2013, 19, 456–459.
23 X.-Z. Shu, S. C. Nguyen, Y. He, F. Oba, Q. Zhang, C. Canlas, 52 A. Ilangovan and P. Sakthivel, RSC Adv., 2014, 4, 55150–
G. A. Somorjai, A. P. Alivisatos and F. D. Toste, J. Am.
Chem. Soc., 2015, 137, 7083–7086.
24 W. Yang, L. Wei, F. Yi and M. Cai, Catal. Sci. Technol., 2016,
6, 4554–4564.
55161.
53 R. Aloise Pilli, L. Fernando Toneto Novaes, V. Maria Teixeira
Carneiro, R. Lopes Drekener and C. Martins Avila, Curr. Org.
Chem., 2015, 12, 523–529.
25 R. Cai, X. Ye, Q. Sun, Q. He, Y. He, S. Ma and X. Shi, ACS 54 R. S. Coleman and E. B. Grant, Tetrahedron Lett., 1990, 31,
Catal., 2017, 7, 1087–1092. 3677–3680.
26 J. T. Sarmiento, S. Suarez-Pantiga, A. Olmos, T. Varea and 55 J. D. Winkler and K. Oh, Org. Lett., 2005, 7, 2421–2423.
G. Asensio, ACS Catal., 2017, 7, 7146–7155. 56 L. Candish and D. W. Lupton, Chem. Sci., 2012, 3, 380–383.
27 M. Chen, Z.-M. Zhang, Z. Yu, H. Qiu, B. Ma, H.-H. Wu and 57 M. Reiter, S. Ropp and V. Gouverneur, Org. Lett., 2004, 6, 91–
J. Zhang, ACS Catal., 2105, 5, 7488–7492. 94.
28 Y. Meng, D. Gu, F. Zhang, Y. Shi, H. Yang, Z. Li, C. Yu, B. Tu 58 M. Reiter, H. Turner, R. Mills-Webb and V. Gouverneur, J.
and D. Zhao, Angew. Chem., 2005, 117, 7215–7221. Org. Chem., 2005, 70, 8478–8485.
29 F. Zhang, Y. Meng, D. Gu, Y. Yan, C. Yu, B. Tu and D. Zhao, J. 59 X.-Z. Shu, X.-Y. Liu, K.-G. Ji, H.-Q. Xiao and Y.-M. Liang,
Am. Chem. Soc., 2005, 127, 13508–13509. Chem.–Eur. J., 2008, 14, 5282–5289.
30 R. Xing, N. Liu, Y. Liu, H. Wu, Y. Jiang, L. Chen, M. He and 60 F. Yang, K. G. Ji, S.-C. Zhao, S. Ali, Y. Y. Ye, X. Y. Liu and
P. Wu, Adv. Funct. Mater., 2007, 17, 2455–2461. Y. M. Liang, Chem.–Eur. J., 2012, 18, 6470–6474.
31 R. Xing, Y. Liu, H. Wu, X. Li, M. He and P. Wu, Chem. 61 L. Zhu, J. Luo and R. Hong, Org. Lett., 2014, 16, 2162–2165.
Commun., 2008, 6297–6299. 62 R. C. Brown, Angew. Chem., Int. Ed., 2005, 44, 850–852.
32 S. Yan, Y. Gao, R. Xing, Y. Shen, Y. Liu, P. Wu and H. Wu, 63 M. Zhang, H. F. Jiang, H. Neumann, M. Beller and
´
Tetrahedron, 2008, 64, 6294–6299.
P. H. Dixneuf, Angew. Chem., Int. Ed., 2009, 48, 1681–1684.
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