Poly(4-vinylimidazolium)s/diazabicyclo[5.4.0]undec-7-ene/zinc(II) bromide-catalyzed cycloaddition of carbon dioxide to epoxides

Article abstract of DOI:10.1002/adsc.201400047

Poly(4-vinylimidazolium)s, derived from the self-immobilization of 4-vinylimidazoliums, with diazabicyclo[5.4.0]undec-7-ene (DBU) and zinc bromide (ZnBr₂) are used as a highly efficient catalyst for the chemical fixation of carbon dioxide. This catalytic system has been applied for the preparation of cyclic carbonates from terminal epoxides and carbon dioxide. Many functional groups, including chloro, vinyl, ether, and hydroxy groups are well tolerated in the reactions. Moreover, the catalytic system was found to catalyze the conversion of more sterically congested epoxides which are generally considered to be challenging substrates for fabricating the cyclic organic carbonates. In addition, the disubstituted epoxides are found to react with retention of configuration. The polymer precatalyst is easily recovered and reused. A plausible reaction mechanism is proposed.

Full text of DOI:10.1002/adsc.201400047

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DOI: 10.1002/adsc.201400047
Poly(4-vinylimidazolium)s/Diazabicyclo[5.4.0]undec-7-ene/
G
Zinc(II) Bromide-Catalyzed Cycloaddition of Carbon Dioxide to
Epoxides
Ue Ryung Seoa and Young Keun Chunga,*
a
Intelligent Textile System Research Center, and Department of Chemistry, College of Natural Sciences, Seoul National
University, Seoul 151-747, Korea
Fax : (+82)-2-889-0310; phone: (+82)-2-880-6662; e-mail: ykchung@snu.ac.kr
Received: January 13, 2014; Revised: February 18, 2014; Published online: && &&, 0000
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201400047.
Abstract: Poly(4-vinylimidazolium)s, derived from
the self-immobilization of 4-vinylimidazoliums, with
diazabicycloACHTUNGTRENNUNG[5.4.0]undec-7-ene (DBU) and zinc bro-
chargeable batteries, and intermediates in the produc-
tion of pharmaceuticals and fine chemicals.[4] There-
fore, a variety of diverse homogeneous and heteroge-
neous catalyst systems[5] has been developed for cata-
lyzing the reactions of CO2 with epoxides. However,
most of them suffer from low catalytic activity, water-
or air-sensitivity of catalyst, and harsh reaction condi-
tions.
Organocatalysts are usually robust, inexpensive,
readily available, and non-toxic. Most of them are
also inert towards moisture and oxygen. Although
a catalyst is not consumed during the process, its sep-
aration from the final products may sometimes be dif-
ficult. Therefore, the recovery and reuse of the cata-
lyst molecules can be a scientific challenge due to
economic and environmental relevance. Recently, the
polymerization of catalysts has been developed as one
of the heterogenization methods.[6] In catalyst poly-
merization, the active centres of a catalyst are distrib-
uted over the polymer chain, which helps to prevent
the loss of activity; therefore, polymerized catalysts
show high activities in certain reactions. The structure
of 4-vinylimidazolium is similar to that of styrene, and
its polymer product, poly(4-vinylimidazolium)s, seems
to be similar to that of polystyrenes. However, reports
mide (ZnBr2) are used as a highly efficient catalyst
for the chemical fixation of carbon dioxide. This
catalytic system has been applied for the prepara-
tion of cyclic carbonates from terminal epoxides
and carbon dioxide. Many functional groups, includ-
ing chloro, vinyl, ether, and hydroxy groups are
well tolerated in the reactions. Moreover, the cata-
lytic system was found to catalyze the conversion of
more sterically congested epoxides which are gener-
ally considered to be challenging substrates for fab-
ricating the cyclic organic carbonates. In addition,
the disubstituted epoxides are found to react with
retention of configuration. The polymer precatalyst
is easily recovered and reused. A plausible reaction
mechanism is proposed.
Keywords: carbon dioxide fixation; cyclic carbo-
nates; cycloaddition; organocatalysis; polymers
Carbon dioxide (CO2) has been attracting much at- on the synthesis and use of poly(4-vinylimidazolium)s
tention as it is considered to a major cause of climate are rare.[7] Very recently, we found that poly(4-vinyl-
change, because of its greenhouse effect.[1] To reduce
ACHTUNGTRENiNUGN midazolium)s derived from the self-immobilization of
the continuous accumulation of CO2 in the atmos- 4-vinylimidazoliums acted as a precatalyst in the car-
phere, the scientific and industrial initiatives have, in boxylation of epoxides with CO2. Herein we commu-
the recent decades, been focused on the chemical con- nicate a very active, stable, recyclable and cost-effec-
version of CO2 to useful chemicals.[2] However, the tive organic precatalyst, poly(4-vinylimidazolium)s,
chemistry of CO2 is limited because of its high stabili- for the carboxylation of epoxides with CO2. The use
ty. One of the potentially useful ways of reducing CO2 of 1-vinyl- and 1,3-divinylimidazole-based cross-
is its reaction with epoxides to form cyclic carbo- linked polymers as the catalyst in the carboxylation of
nates.[3] This reaction has tremendous potential be- epoxides with CO2 has been reported.[8] Moreover,
cause cyclic carbonates are widely used as the precur- the use of polyACTHNUTRGNEU[GN 1,3-bis(4-vinylbenzyl)imidazolium]Cl-
sors of polycarbonates and other polymers, serve as based cross-linked polymers as the catalyst in carbox-
excellent aprotic polar solvents, electrolytes in re- ylation of epoxides with CO2 has also been report-
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Ue Ryung Seo and Young Keun Chung
Scheme 1. Synthesis of 2 from histamine.
ed.[9] However, all the reactions were carried out at conditions (2 mol% catalyst, ZnI2 as the Lewis acid,
high temperatures and high pressures of CO2. K2CO3 as the base, DMSO as the solvent, at 808C re-
Previously, the 4-vinylimidazolium salt was pro- action temperature, and 24 h of reaction time) adopt-
duced by the decarboxylation of urocanic acid.[7] ed from the previous work[14] on the NHC-catalyzed
However, histidine can also be used to obtain 4-vinyl- carboxylation of epoxides. The coupling of styrene
A
oxide (SO) with CO2 to afford styrene carbonate (SC)
Both histidine and histamine are commercially was chosen as the model reaction. When the reaction
available. We chose histamine as the starting material.
The reaction of histamine with NaNO2, followed by
chlorination reaction with SOCl2, afforded 4-(2-
Table 1. Screening for the reaction conditions.[a]
chloroACHTUNGTRENNUNG
ethyl)imidazole in 74% yield.[10] Dehydrochlori-
nation and dimethylation of 4-(2-chloroethyl)imida-
zole in the presence of NaHCO3, K2CO3 and MeI in
acetonitrile afforded an 4-vinylimidazolium salt, 1, in
70% yield.[11] Polymerization of 1 in the presence of
AIBN afforded poly(4-vinylimidazolium)s, 2, the pre-
cursor of an organocatalyst, in high yield.[12] Broad
1H NMR signals were observed, as expected for
a high molecular weight polymer. The polymer was
soluble in DMSO and DMF, and freely soluble in
water, but insoluble in chloroform, dichloromethane,
and acetone. The weight average molecular weight
(MW) of 2 was found to be ~30000 from light scatter-
ing experiments.[13] The polymer decomposed at
3508C. The abilities of 1 and 2 to catalyze the carbox-
ylation of epoxides with CO2 in the presence of
a base were examined [Eq. (1)].
Entry 2
(mol%)
Solvent Base
(mol%)
Lewis
acid
Yield
[%][b]
1
2
DMSO K2CO3 (2) ZnI2
86
88
95
99
90
94
76
72
77
77
50
87
94
4
2
3
4
5
6
7
8
9
10
11[c]
12[d]
13[e]
14
15
16
2
2
2
1
1
1
1
1
1
1
1
1
1
–
–
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
DMF
K2CO3 (2) ZnI2
DBU (2)
DBU (4)
DBU (2)
DBU (2)
DBU (2)
DBU (2)
DBU (2)
DBU (2)
DBU (2)
DBU (2)
DBU (2)
–
ZnI2
ZnI2
ZnI2
ZnBr2
ZnCl2
CrCl3
LiI
FeCl3
ZnBr2
ZnBr2
ZnBr2
–
DBU (2)
–
–
N.R
11
ZnBr2
[a]
Reaction conditions: Styrene oxide (SO) (5 mmol), 2,
Lewis acid (the same equiv. of 2), solvent (3 mL), base,
and CO2 (1 atm) at 808C for 24 h.
Isolated yield.
Reaction was performed at 608C.
Reaction was performed at 1008C.
Reaction time: 10 h.
First, the reaction conditions were screened, includ-
ing the CO2 pressure, reaction temperature, reaction
time, solvent, base, and the catalyst amount to opti-
mize the yield of the cyclic carbonate (Table 1). Ini-
tially, the study was performed under the reaction
[b]
[c]
[d]
[e]
2
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Poly(4-vinylimidazolium)s/DiazabicycloACTHUNRGTNEUNG[5.4.0]undec-7-ene/Zinc(II)
was carried out under the adopted reaction condi-
tions, the SC yield was 86% (Table 1, entry 1). Chang-
ing the solvent to DMF afforded a slightly higher SC
yield (entry 2: 88% yield). When diazabicyclo-
ACHTUNGTRENNUNG[5.4.0]undec-7-ene (DBU) was used instead of K2CO3
in DMF, SC was obtained quantitatively (entries 3
and 4). When the amount of catalyst 2 was reduced to
1 mol%, the yield was still high (entry 5, 90% yield).
Thus, in the presence of 1 mol% of 2, the effect of
metal ions, such as ZnX2 (X=Cl, Br, and I), CrCl3,
LiI, and FeCl3, on the reaction was also examined
(entries 5–10). The SC yield was greatly affected by
the different metal ions. Among them, the use of
ZnBr2 afforded the best result (entry 6, 94% yield),
because of its strong Lewis acidity. The reactivity of
different anions in the zinc salts decreased in the fol-
lowing order: BrÀ >IÀ >ClÀ.[15] The different reactivi-
Figure 1. Recycling of polyACTHNURGTNE(UNG NHC-Zn) complex in the cyclo-
addition of CO2 to SC.
ty may be due to the different electrophilicity of Zn (Table 2). To our delight, many functional groups, in-
depending upon the anion.[13] The effect of the reac- cluding chloro, vinyl, ether, and hydroxy groups were
tion temperature on the product yield was also exam- well tolerated in the reactions. Thus, all the epoxides
ined (entries 6, 11, and 12). In the lower temperature used except propylene oxide (entry 6) could be trans-
range, the yield increased with the increasing temper- formed to the corresponding carbonates in almost
ature (entry 6 vs 11); however, this trend was not ob- quantitative yields. In the case of propylene oxide,
served at higher temperatures. The yield decreased to a slightly lower yield (56%) was observed because of
87% at 1008C (entry 6 vs. 12). The reaction proceed- its low boiling point (338C).
ed well with 1 mol% of catalyst at 808C. When the re-
Notably, most of the substrates afforded the desired
action time was reduced to 10 h, the excellent yield products under mild reaction conditions, and the func-
was maintained (entry 13, 94% yield). The necessity tional groups were stable in the reactions, indicating
of a combination of 2, DBU, and a Lewis acid in the the outstanding efficiency of the catalyst. This catalyt-
reaction was confirmed by the observation that in the ic reaction may be a good method for preparing func-
presence of solely 2, DBU, or ZnBr2 a negligible reac- tional monomers.
tion was observed (entries 14–16).
Owing to the steric hindrance and electronic effect,
Thus, the optimum reaction conditions were estab- 1,1-disubstituted and internal disubstituted epoxides
lished as follows: 1 mol% catalyst, 2 mol% DBU, and are often considered to be more challenging sub-
1 mol% ZnBr2 in DMF at 808C under 1 atm CO2 for strates for fabricating the cyclic organic carbonates.[16]
10 h. Under the optimized reaction conditions, the A series of these substrates (Table 3) was investigated
maximum turnover number was 320 (see the Support- using the catalyst system. The amounts of 2, ZnBr2,
ing Information). When 1 was used as the precatalyst and DBU were used four times more than those used
under the optimized reaction conditions, SC was ob- for the cycloaddition of CO2 with terminal epoxides
tained in 88% yield. The experiments were also car- (see the Supporting Information). As expected,
ried out to examine the recyclability of the catalyst higher pressures and temperatures were needed to
using SO as the substrate. The amount of 2 was too convert the substrates to the corresponding organic
small to confirm the recycling test; therefore, twice carbonates; e.g., the cycloaddition of 1,1-dimethylox-
the amounts of 2, ZnBr2, and DBU as those used irane with CO2 at 908C and 1 atm of CO2 was unsuc-
during optimization were used. After performing the cessful. However, under 5 atm of CO2 pressure, 1,1-di-
reaction in DMF, excess MeOH was added to the re- methyloxirane was converted into 4,4-dimethyl-1,3-di-
action mixture to precipitate the polymer catalyst. oxolan-2-one in 46% yield after 24 h of reaction time.
The recovered polymer catalyst was dried and reused When the CO2 pressure was increased to 7 atm and
for the next run. The SC yields for the eight consecu- 10 atm, the yields of 4,4-dimethyl-1,3-dioxolan-2-one
tive runs were 99%, 98%, 91%, 97%, 97%, 94%, increased to 53% and 83% yields, respectively. Thus,
94%, and 91%. Considering the weight loss in the cat- the reactions of other substrates with CO2 were car-
alyst purification process, no considerable decrease in ried out at 908C under 10 atm of CO2. When the CO2
the SC yield was observed (Figure 1).
pressure was increased, most of the substrates afford-
To show the catalytic activity of 3 [3=poly
ACHTUNGTRENNUNG
NHC=1,3-dimethyl-4-vinylimidazol-2-ylidene],
coupling reactions of CO2 to various substituted epox- tively low yield (35%) was observed after 24 h of re-
ides were also conducted at 808C and 1 atm CO2 action time. The yield increased to 55% when the re-
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Table 2. Cycloaddition of CO2 with various terminal epox-
ides.[a]
Table 3. Cycloaddition of CO2 with various internal epox-
ides.[a]
N
ACHTUNGTRENNUNG
[a]
The catalyst (4 mol%), ZnBr2 (4 mol%), DBU (8 mol%),
expoxide (5 mmol), DMF (4 mL), CO2 (10 atm), 908C,
24 h.
Isolated yields.
48 h
[b]
[c]
[a]
[b]
1 mol% of 2, epoxide (5 mmol), ZnBr2 (1 mol%), DBU
(2 mol%), CO2 (1 atm), 808C, 10 h.
Isolated yields.
However, in the case of 2,2,3,3-tetramethyloxirane,
no reaction was observed under the reaction condi-
tions (908C, 10 atm CO2, 24 h). When the reaction
time was prolonged to 72 h, no reaction was ob-
served.
action time was increased to 48 h. Moreover, ethyl 2-
The internal epoxides provided an opportunity to
oxo-5-phenyl-1,3-dioxalane-4-carboxylate
(entry 6) study the stereochemistry of this cyclic carbonate syn-
1
was found to be a good substrate.[17]
thesis. According to their H and 13C NMR spectra,
4
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Poly(4-vinylimidazolium)s/DiazabicycloACTHUNRGTNEUNG[5.4.0]undec-7-ene/Zinc(II)
Table 4. Cycloaddition under various reaction conditions.[a]
yield. Thus, the presence of both ZnBr2 and DBU is
necessary for achieving good results similar to those
obtained with other Lewis acid and Lewis base co-cat-
alyzed coupling reactions of CO2 with epoxides.[3,22]
Furthermore, the best result was obtained when the
reaction was carried out in the presence of 2, DBU,
and ZnBr2 (2-DBU-ZnBr2) catalyst system (entry 8,
Entry 2
3-CO2
DBU
(mol%)
ZnBr2
(mol%)
Yield
[%]
1
(mol%) (mol%)
94% yield). The H NMR spectra of 2, 2/DBU, and 2/
DBU/ZnBr2 in [D7]DMF were taken at room temper-
1
2
3
4
5
6
7
8
0
0
1
0
1
0
0
1
0
0
0
0
0
1
1
0
0
2
2
2
0
0
0
2
1
1
0
0
1
0
1
1
11
43
8
N.R
45
N.R
33
94
ature and 808C (see the Supporting Information), the
À
imidazolium C H peak of 2 appeared at d=9.15 ppm
and was observed in the presence of DBU even at
808C. However, in the presence of DBU and ZnBr2,
it disappeared at 808C and reappeared at room tem-
perature. Thus, we envision the formation of 3-ZrBr2
at 808C.
[a]
Although the exact mechanism of this transforma-
tion is not clear at the moment, a plausible reaction
mechanism was proposed on the basis of the experi-
mental observations (Figure 2).
Styrene oxide (SO) (5 mmol), DMF (3 mL), CO2 (1
atm), 808C, 10 h.
the cyclic carbonates, (Æ)-trans-4,5-dimethyl-1,3-diox-
We envision that the NHC-ZnBr2 species may play
olan-2-one and (Æ)-trans-4,5-diphenyl-1,3-dioxolan-2- a major role in the coupling reaction at 808C, i.e., the
one, had the same stereochemistry as that of the start- reaction may be co-catalyzed by a Lewis base, DBU,
ing epoxides. Thus, the disubstituted epoxides were and Lewis acid, NHC-ZnBr2 or ZnBr2. The Lewis
found to react with retention of configuration.
base and Lewis acid act together to open the epoxy
To better understand the reaction mechanism, vari- ring and then react with CO2 to afford the corre-
ous reaction conditions were tested (Table 4). The re- sponding cyclic carbonates via a ring-opening and re-
action of SO in the presence of ZnBr2 alone afforded cyclization process. When a pre-synthesized polymer-
SC in 11% yield (entry 1). The same reaction in the NHC-ZnBr2 complex was used as a catalyst, SC was
presence of ZnBr2 and DBU[18] afforded SC in 43% obtained in 93% yield. This observation also supports
isolated yield (entry 2). We expected that the reaction the mechanism shown in Figure 2.
of 2 with DBU would afford 3; however, SC was ob-
In conclusion, we have examined an efficient
tained in 8% yield (entry 3). This observation suggest- poly(4-vinylimidazolium)s-DBU-ZnBr2
ed that 3 would not be generated in situ. The rapid
CO2 fixation by DBU and the coupling of aziridine to
CO2 in the presence of DBU have been well docu-
mented.[19] However, DBU by itself did not catalyze
the reaction (entry 4). The use of imidazolium-based
polymeric ionic liquids as catalyst in the reaction of
the coupling of CO2 with epoxides has been report-
ed.[9,20] Thus, the reaction of SO with CO2 in the pres-
ence of 2 and ZnBr2 was examined; and SC was ob-
tained in 45% yield (entry 5). The NHC-CO2 adduct
has been reported to be a potent organocatalyst at
high temperatures and high pressures (100–1208C and
20–100 atm of CO2 and).[9,20a,21] Thus, the 3-CO2
adduct was prepared (see the Supporting Informa-
tion) and used as the catalyst under the above-men-
tioned reaction conditions. However, no reaction was
observed in the presence of 3-CO2 adduct (entry 6).
Furthermore, the IR spectrum of the recovered poly-
catalyst
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
CO2 adduct itself did not play an important role in
the catalytic reaction. Interestingly, when the same re-
action was carried out in the presence of 3-CO2
Figure 2. Plausible mechanism of cycloaddition of epoxide
adduct and ZnBr2 (entry 7), SC was obtained in 33% to CO2
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[4] a) A. A. G. Shaikh, S. Sivaram, Chem. Rev. 1996, 96,
951; b) J. H. Clements, Ind. Eng. Chem. Res. 2003, 42,
663; c) B. Schꢁffner, F. Schꢁffner, S. P. Verevkin, A.
Bcrner, Chem. Rev. 2010, 110, 4554.
[5] For reviews, see: a) A. Decortes, A. M. Castilla, A. W.
Kleij, Angew. Chem. 2010, 122, 10016; Angew. Chem.
Int. Ed. 2010, 49, 9822; b) X.-B. Liu, D. J. Darensbourg,
Chem. Soc. Rev. 2012, 41, 1462; c) D. J. Darensbourg,
Chem. Rev. 2007, 107, 2388; d) W.-L. Dai, S.-L. Luo,
S. F. Yin, C.-T. Au, Appl. Catal. A: 2009, 366, 2.
[6] a) H. G. Alt, J. Chem. Soc. Dalton Trans. 1999, 1703;
b) J. Zhang, X. Wang, G.-X. Jin, Coord. Chem. Rev.
2006, 250, 95.
system for the synthesis of cyclic carbonates by react-
ing terminal epoxides and internal epoxides with CO2.
Cyclic carbonate is the sole product in this reaction.
Efforts are underway to elucidate the mechanistic de-
tails of the reaction and extend the applications of the
catalyst system.
Experimental Section
General Procedure for the Synthesis of Mono-
Subsitituted Cyclic Carbonates
[7] a) C. G. Overberger, N. Vorchheimer, J. Am. Chem.
Soc. 1963, 85, 951; b) C. G. Overberger, R. C. Glowaky,
T. J. Pacansky, K. N. Sannes, Macromol. Synth. 1974, 5,
43; c) J. Wang, T. W. Smith, Polym. Prepr. Am. Chem.
Soc. Div. Polym. Chem. 2004, 45, 290; d) T. W. Smith,
M. Zhao, F. Yang, D. Smith, P. Cebe, Macromolecules
2013, 46, 1133.
[8] a) Y. Xie, Z. Zhang, T. Jiang, J. He, B. Han, T. Wu, K.
Ding, Angew. Chem. 2007, 119, 7393; Angew. Chem.
Int. Ed. 2007, 46, 7255; b) Y. Xiong, Y. Wang, H. Wang,
R. Wang, Z. Cui, J. Appl. Polym. Sci. 2012, 123, 1486.
Reactions were performed in a Schlenk tube equipped with
a stirring bar and capped with a rubber cap and the follow-
ing were placed in the tube in order: 1 mol% of catalyst
(13 mg, 0.05 mmol), 1 mol% of ZnBr2 (12 mg, 0.05 mmol),
2 mol% of DBU (15 mL, 0.1 mmol) and 1 mL of DMF. while
they were mixing together, tube was charged with CO2 by
balloon for 30 seconds. Then, mono-substituted epoxide
(5 mmol) and 2 mL of DMF were put into the Schlenk tube.
The mixture was stirred at 808C for 10 h and CO2 was pro-
vided by a balloon (1 atm). The reaction mixture was taken
up in methanol and catalysts were filtered and filtrate was
concentrated under reduced pressure. Purification by flash
chromatography on silica gel with n-hexane and ethyl ace-
tate afford the cyclic carbonates.
˘
[9] S. Ghazali-Esfahani, H. Song, E. Paunescu, F. D. Bob-
bink, H. Liu, Z. Fei, G. Laurenczy, M. Bagherzadeh, N.
Yana, P. J. Dyson, Green Chem. 2013, 15, 1584.
[10] Y. Takecuchi, S. Ozaki, M. Satoh, K.-i. Mimura, S.-i.
Hara, H. Abe, H. Nishioka, T. Harayama, Chem.
Pharm. Bull. 2010, 58, 1552.
[11] A. Monney, G. Venkatachalam, M. Albrecht, Dalton
Acknowledgements
Trans. 2011, 40, 2716.
[12] H. Sellner, C. Faber, P. B. Rheiner, D. Seebach, Chem.
Eur. J. 2000, 6, 3692.
This work was supported by the National Research Founda-
tion of Korea (NRF) (2007-0093864) and the Basic Science
Research Program through the NRF funded by the Ministry
of Education, Science and Technology (R11-2005-065). URS
thanks the Brain Korea 21 Plus Fellowships.
[13] We tentatively assigned a molecular weight (ca. 30,000)
of the polymer. An accurate molecular weight mea-
surement was not possible because of aggregations and
interactions among charged polymers. The 30,000 value
was obtained from a Zimm plot of diluted DMF solu-
tions of the polymer. For molecular weight determina-
tions of charged polymers, see the following papers:
a) M. D. Green, T. E. Long, J. Macromol. Sci. Part C:
Polym. Rev. 2009, 49, 291; b) E. B. Anderson, T. E.
Long, Polymer 2010, 51, 2447; c) J. Pinaud, J. Vignolle,
Y. Gnanou, D. Taton, Macromolecules 2011, 44, 1900.
[14] X. Liu, C. Cao, Y. Li, P. Guan, L. Yang, Y. Shi, Synlett
2012, 1343.
[15] L. Xiao, D. Lv, W. Wu, Catal. Lett. 2011, 141, 1838.
[16] a) D. P. Sanders, K. Fukushima, D. J. Coady, A. Nelson,
M. Fujiwara, M. Yasumoto, J. L. Hedrick, J. Am.
Chem. Soc. 2010, 132, 14724; b) C.-Y. Li, C.-R. Wu, Y.-
C. Liu, B.-T. Ko, Chem. Commun. 2012, 48, 9628;
c) C. J. Whiteoak, N. Kielland, V. Laserna, E. C. Escu-
dero-Adꢂn, E. Martin, A. Kleij, J. Am. Chem. Soc.
2013, 135, 1228; d) C. J. Whiteoak, E. Martin, M. Martꢃ-
nez Belmonte, J. Benet-Buchholz, A. W. Kleij, Adv.
Synth. Catal. 2012, 354, 469.
References
[1] a) M. Aresta, A. Dibenedetto, Dalton Trans. 2007, 28,
2975; b) K. Huang, C.-L. Sun, Z.-J. Shi, Chem. Soc.
Rev. 2011, 40, 2435.
[2] a) C. J. Liu, R. Mallinson, M. Aresta (Eds.), Utilization
of Green House Gases, American Chemical Society,
Washington, DC, 2003; b) S. N. Riduan, Y. Zhang,
Dalton Trans. 2010, 39, 3347; c) B.-L. Lu, L. Dai, M.
Shi, Chem. Soc. Rev. 2012, 41, 3318; d) A. M. Appel,
J. E. Bercaw, A. B. Bocarsly, H. Dobbek, D. L. DuBois,
M. Dupuis, J. G. Ferry, E. Fujita, R. Hille, P. J. A.
Kenis, C. A. Kerfeld, R. H. Morris, C. H. F. Peden,
A. R. Portis, S. W. Ragsdale, T. B. Rauchfuss, J. N. H.
Reek, L. C. Seefeldt, R. K. Thauer, G. L. Waldrop,
Chem. Rev. 2013, 113, 6621; e) M. Aresta, A. Dibene-
detto, A. Angelini, Chem. Rev. ASAP; DOI: 10.1021/
cr4002758.
[17] C. J. Whiteoak, E. Martin, E. Escudero-Adꢂn, A. W.
[3] a) D. J. Darensbourg, M. W. Holtcamp, Coord. Chem.
Rev. 1996, 153, 155; b) T. Sakakura, K. Kohno, Chem.
Commun. 2009, 1312; c) D. J. Darensbourg, S. J.
Wilson, Green Chem. 2012, 14, 2665.
Kleij, Adv. Synth. Catal. 2013, 355, 2233.
[18] Y.-M. Shen, W.-L. Duan, M. Shi, J. Org. Chem. 2003,
68, 1559–1562.
6
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COMMUNICATIONS
Poly(4-vinylimidazolium)s/DiazabicycloACTHUNRGTNEUNG[5.4.0]undec-7-ene/Zinc(II)
[19] a) B. Ochiai, K. Yokota, A. Fujii, D. Nagai, T. Endo,
Macromolecules 2008, 41, 1229; b) D. J. Heldebrant,
P. G. Jessop, C. A. Thomas, C. A. Eckert, C. L. Liotta,
J. Org. Chem. 2005, 70, 5335; c) J. M. Hooker, A. T.
Reibel, S. M. Hill, M. J. Schueller, J. S. Fowler, Angew.
Chem. 2009, 121, 3534; Angew. Chem. Int. Ed. 2009, 48,
3482.
He, J. Gao, Z.-S. Yin, Green Chem. 2012, 14, 519; e) L.
Han, H.-J. Choi, S.-J. Choi, B. Liu, D.-W. Park, Green
Chem. 2011, 13, 1023.
[21] a) H. Zhou, W.-Z. Zhang, C.-H. Liu, J.-P. Qu, X.-B. Lu,
J. Org. Chem. 2008, 73, 8039; b) Y. Kayaki, M.; Yama-
moto, T. Ikariya, Angew. Chem. 2009, 121, 4258;
Angew. Chem. Int. Ed. 2009, 48, 4194.
[20] a) T.-Y. Shi, J.-Q. Wang, J. Sun, M.-H. Wang, W.-G.
Cheng, S.-J. Zhang, RSC Adv. 2013, 3, 3726; b) Y.
Xiong, Y. Wang, H. Wang, R. Wang, Z. Cui, J. Appl.
Polym. Sci. 2012, 123, 1486; c) R. A. Watile, K. M.
Deshmukh, K. P. Dhake, B. M. Bhanage, Catal. Sci.
Technol. 2012, 2, 1051; d) Z.-Z. Yang, Y.-N. Zhao, L.-N.
[22] a) T. Yano, H. Matsui, T. Koike, H. Ishiguro, H. Fuji-
hara, M. Yoshihara, T. Maeshima, Chem. Commun.
1997, 1129; b) T. Chang, H. Jing, L. Jin, W. Qiu, J. Mol.
Catal. A: Chem. 2007, 264, 241; c) Y.-M. Shen, W.-L.
Duan, M. Shi, J. Org. Chem. 2003, 68, 1559.
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Adv. Synth. Catal. 2014, 356, 1 – 8
Ue Ryung Seo, Young Keun Chung*
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