A protic ionic liquid catalyzes CO2 conversion at atmospheric pressure and room temperature: Synthesis of quinazoline-2,4(1H,3H)-diones

Article abstract of DOI:10.1002/anie.201400521

The chemical fixation of CO₂ under mild reaction conditions is of significance from a sustainable chemistry viewpoint. Herein a CO ₂-reactive protic ionic liquid (PIL), [HDBU⁺][TFE ^-], was designed by neutralization of the superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with a weak proton donor trifluoroethanol (TFE). As a bifunctional catalyst for simultaneously activating CO₂ and the substrate, this PIL displayed excellent performance in catalyzing the reactions of CO₂ with 2-aminobenzonitriles at atmospheric pressure and room temperature, thus producing a series of quinazoline-2,4(1H,3H)-diones in excellent yields. No pressure: The reaction of CO₂ with various 2-aminobenzonitriles was achieved at atmospheric pressure and room temperature by using the bifunctional protic ionic liquid [HDBU⁺][TFE^-], thus producing the title compounds in excellent yields. The ionic liquid serves as both the catalyst and solvent, and activates both CO₂ and the substrates simultaneously. DBU=1,8-diazabicyclo[5.4.0]undec-7-ene, TFE=trifluoroethanol.

Full text of DOI:10.1002/anie.201400521

Angewandte
Chemie
DOI: 10.1002/anie.201400521
Heterocycles
A Protic Ionic Liquid Catalyzes CO2 Conversion at Atmospheric
Pressure and Room Temperature: Synthesis of Quinazoline-2,4-
(1H,3H)-diones**
Yanfei Zhao, Bo Yu, Zhenzhen Yang, Hongye Zhang, Leiduan Hao, Xiang Gao, and
Zhimin Liu*
Abstract: The chemical fixation of CO2 under mild reaction
conditions is of significance from a sustainable chemistry
viewpoint. Herein a CO2-reactive protic ionic liquid (PIL),
[HDBU+][TFEÀ], was designed by neutralization of the
superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with
a weak proton donor trifluoroethanol (TFE). As a bifunctional
catalyst for simultaneously activating CO2 and the substrate,
this PIL displayed excellent performance in catalyzing the
reactions of CO2 with 2-aminobenzonitriles at atmospheric
pressure and room temperature, thus producing a series of
quinazoline-2,4(1H,3H)-diones in excellent yields.
version of CO2 at atmospheric pressure and room temper-
ature is still a challenge.
Ionic liquids (ILs) composing of organic cations and
inorganic/organic anions have unique features such as high
thermal and chemical stability, negligible vapor pressure, easy
recyclability, and tunable properties, which have been applied
in many areas.[6] Specifically, task-specific ILs have displayed
superior performance for CO2 capture and conversion
through careful design and choice of novel component ions
to endow them with unique properties.[4c,d,h,7] For example,
superbase-derived protic ionic liquids (PILs) were presented
to be excellent media for rapid and reversible capture of CO2
under mild reaction conditions.[7b] CO2 could react with PILs
to form liquid carbonate, carbamate, or phenolate salts, which
might result in activation of CO2, thus rendering the chemical
transformation of CO2 under mild reaction conditions.
Inspired by this progress, we designed a CO2-reactive PIL
using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a super-
base and trifluoroethanol (TFE) as a proton donor, denoted
as [HDBU+][TFEÀ]. This PIL could adsorb CO2 with
maximum molar ratio CO2/IL of 1.01 at atmospheric pressure
and room temperature (see the Supporting Information), thus
suggesting that it was a good absorbent for CO2 with a capacity
comparable to those reported PILs.[7b]
C
hemical conversion of CO2 is an alternative for CO2
utilization, and has been paid much attention in the past
decades.[1] In comparison with toxic phosgene and CO, CO2 is
an abundant, easily available, environmentally friendly, and
renewable C1 building block. However, CO2 conversion is
limited because of its inherent thermodynamic stability, thus
resulting in low reactivity. In this context, the key issue to
convert CO2 into useful chemicals under mild reaction
conditions will inevitably rely on its activation. Therefore,
effective catalytic systems are highly required. So far, many
efficient catalysts have been developed for CO2 conversion
into high-value chemicals such as methanol,[2] formic acid,[3]
and others.[4] However, high temperature and pressure are
generally needed. In recent years, researchers have paid much
attention to chemically converting CO2 under mild reaction
conditions, especially at atmospheric pressure and room
Quinazoline-2,4(1H,3H)-diones can serve as intermedi-
ates for the synthesis of pharmaceuticals.[8] The reaction of
CO2 with 2-aminobenzonitriles is an atom-economical route
for the synthesis of these compounds, and it has been widely
investigated using various catalysts including DBU,[9]
Cs2CO3,[10] MgO-ZrO2,[11] [Bmim]OH,[12] N-methyl-tetrahy-
temperature.[5] Kimura et al. reported [(n-C4H9)4N]2 [WO4]2À
+
as a bifunctional catalyst which could catalyse the reactions of
CO2 with various aromatic diamines at atmospheric pressure
around 1008C.[5g] More recently, cobalt-coordinated conju-
gated microporous polymers were reported to function as
heterogeneous catalysts for the reaction of CO2 with propyl-
ene oxide at atmospheric pressure and room temperature.[5h]
Though much progress has been made, the chemical con-
+
dropyrimidine,[13] guanidines,[14] [(n-C4H9)4N]2 [WO4]2À,[5g,15]
and 1-butyl-3-methylimidazolium acetate ([Bmim]Ac).[16]
However, in these studies a high CO2 pressure and tem-
perature were generally required. In this work, we have
found that by using [HDBU+][TFEÀ] as the catalyst and
solvent, the CO2 reaction with 2-aminobenzonitriles at
atmospheric pressure and room temperature produces
a
series of quinazoline-2,4(1H,3H)-diones in excellent
yields. Moreover, the IL could be easily recovered and
reused without activity loss.
[*] Dr. Y. F. Zhao, B. Yu, Dr. Z. Z. Yang, Dr. H. Y. Zhang, L. D. Hao,
X. Gao, Prof. Z. M. Liu
[HDBU+][TFEÀ] was synthesized by neutralization of
DBU and TFE, as illustrated in Scheme 1. The character-
ization for this IL is given in the Supporting Information, and
Institute of Chemistry, Chinese Academy of Sciences
No. 2, Zhongguancun Beiyijie, Beijing 100190 (China)
E-mail: liuzm@iccas.ac.cn
1
the H NMR data (Figure S1) and FTIR (Figure S2) analysis
[**] This work was financially support by the National Natural Science
Foundation of China (Nos. 21125314, 21021003).
confirm its formation. For comparison, other three ILs with
different cations and anions, including, [HDBU+]-
[CH3COOÀ], [HTMG+][TFEÀ], and [Et-DBU+][TFEÀ]
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201400521.
Angew. Chem. Int. Ed. 2014, 53, 1 – 5
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

.
Angewandte
Communications
Table 2: Synthesis of various quinazoline-2,4 (1H,3H)-diones.[a]
Scheme 1. Preparation of [HDBU+][TFEÀ].
Entry
1[c]
Substrate
Product
Yield [%][b]
Table 1: Reaction of 2-aminobenzonitrile with CO2 catalyzed by different
97
IL catalysts.[a]
Entry
Catalyst/Solvent
Yield [%][b]
1
2
3
4
–
0
[HDBU+][TFEÀ]
[HDBU+][CH3COOÀ]
[HTMG+][TFEÀ]
[Et-DBU+] [TFEÀ]
97
15
67
7[c]
90
2
68[d]
5
6[d]
[(n-C4H9)4N]2 [WO4]2À
+
[a] Reaction conditions: 2-aminobenzonitrile (1 mmol), catalyst
(3 mmol), CO2 (0.1 MPa), 303 K, 24 h. [b] Yield of isolated product.
[c] determined by LC analysis. [d] DMSO (1 mL), catalyst (0.02 mmol),
CO2 (0.1 MPa), 373 K, 120 h.[5g]
3
92
4
96[d]
(TMG = 1,1,3,3-tetramethylguanidine), were synthesized (see
the Supporting Information).
The reaction of CO2 with 2-aminobenzonitrile was carried
out in the absence and presence of the as-synthesized ILs, and
the results are listed in Table 1. This reaction did not proceed
in the absence of any catalyst. To our delight, [HDBU+]-
[TFEÀ] as the catalyst showed high efficiency for this reaction
(see Figures S3 and S4 in the Supporting Information), thus
producing quinazoline-2,4(1H,3H)-dione in 97% yield, with-
out any byproducts, within 24 hours (Table 1, entry 2). More-
over, [HDBU+][TFEÀ] served as a solvent, which allowed the
reaction to proceed more rapidly than the reported sys-
tems.[5g] For comparison, three other ILs were examined for
catalyzing this reaction. It was indicated that they were also
effective, however, they showed lower activities (Table 1,
entries 3–5). The differences in their chemical structures may
be responsible for their activities. [HDBU+][CH3COOÀ],
having the same cation as [HDBU+][TFEÀ], afforded a much
lower product yield (15%), thus indicating that the anions of
the PILs influence the activities of the catalysts. Additionally,
[HTMG+][TFEÀ] and [Et-DBU+][TFEÀ], which have the
same anion as [HDBU+][TFEÀ], also gave lower product
yields (67 and 7%, respectively), thus suggesting that the
cations of the ILs affected the activities of the catalysts as
well. From the above findings, it can be inferred that both the
cations and anions of these ILs played important role in the
reaction.
5
92
6
90
7
95
8[e]
95
[a] Reaction conditions: Reactant (1 mmol), [HDBU+][TFEÀ] (6 mmol),
CO2 (0.1 MPa), 303 K, 24 h. [b] Yield of isolated product. [c] [HDBU+]-
[TFEÀ] (3 mmol). [d] Determined by LC analysis. [e] [HDBU+][TFEÀ] used
for the fifth time.
24 hours. For example, 2-amino-4,5-dimethoxybenzonitrile
The [HDBU+][TFEÀ]-catalyzed system could be applied
to various 2-aminobenzonitriles reacting with CO2 at atmos-
pheric pressure and room temperature (Table 2). It was
demonstrated that all reactions proceeded smoothly, thus
producing the corresponding quinazoline-2,4(1H,3H)-diones.
With the exception of 4-methyl-2-aminobenzonitrile (Table 2,
entry 2), the other 2-aminobenzonitriles, having substituents
including methoxy, fluoro, chloro, and bromo groups, gen-
erated the corresponding products in excellent yields within
afforded a 96% yield of 6,7-dimethoxyquinazoline-2,4-
(1H,3H)-dione (Table 2, entry 3), which is a key intermediate
in the synthesis of Prazosin, IAAP, and Doxazosin.[8b] The
above results indicate that the substituents in the phenyl ring
of 2-aminobenzonitriles have little effect on the reactivity
with CO2, and [HDBU+][TFEÀ] was highly efficient for
catalyzing these reactions.
In addition, the reusability of [HDBU+][TFEÀ] was
evaluated for the synthesis of quinazoline-2,4(1H,3H)-dione
2
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 1 – 5
These are not the final page numbers!

Angewandte
Chemie
from CO2 and 2-aminobenzonitrile. It was demonstrated that
the product yield almost remained unchanged as the same IL
was used for five reactions (Table 2, entry 8), thus suggesting
the designed IL maintained its original performance and was
recyclable.
To explore the reaction mechanism, the interactions of
[HDBU+][TFEÀ] with CO2 and substrate were examined by
NMR spectroscopy and IR analysis. The absorption of CO2 by
[HDBU+][TFEÀ] was examined by FTIR and NMR analyses.
In the 13C NMR spectrum, a new signal appeared at d =
167.7 ppm (Figure 1), which was attributed to the carbonyl
Figure 2. 15N NMR spectrum of [HDBU+][TFEÀ] and 2-aminobenzo-
nitrile, with and without [HDBU+][TFEÀ] ([D6]DMSO, 298 K).
hydrogen bonding between [HDBU+] and the substrate was
very important for the synthesis of quinazoline-2,4(1H,3H)-
dione from CO2 reacting with 2-aminobenzonitrile. In addi-
tion, the 13C NMR signal, assigned to C1 in [TFEÀ], shifted
downfield from d = 58.94 to 58.98 ppm as the IL was mixed
with 2-aminobenzonitrile (see Figure S7 in the Supporting
Information), further indicating the formation of hydrogen
bonding between [TFEÀ] and the substrate. The above results
indicated that both the cation and anion of the IL could form
hydrogen bonds with the substrate, and could weaken the
Figure 1. 13C NMR spectrum of pure [HDBU+][TFEÀ] and the intermedi-
ate derived from exposure of [HDBU+][TFEÀ] to CO2 (0.1 MPa; D2O,
0.6 mL, 298 K).
carbon atom of the carbonate and suggests that CO2 was
activated by the anion [TFEÀ], thus forming a carbonate
intermediate. This intermediate in agreement with those
previously reported.[7b] In our previous work we found that
[HDBU+] could activate CO2 at 9 MPa and thus had
a
13C NMR signal at d = 172.3 ppm,[4h] however, in this work
N H bond in NH2 of 2-aminobenzonitrile, thus facilitating
À
the absence of this signal implies that at atmospheric pressure
[HDBU+] could not activate CO2. In the FTIR spectrum
a new band appeared at 1702 cmÀ1 (see Figure S5 in the
Supporting Information), which is assigned to the stretching
the nucleophilic attack of the NH2 group in 2-aminobenzoni-
trile on the carbon atom of the activated CO2. From the above
analysis, it can be deduced that the IL can serve as a bifunc-
tional catalyst for simultaneously activating CO2 and the
substrate at atmospheric pressure and room temperature.
On the basis of the experimental results and previous
reports,[5g,9–16] a possible mechanism for the [HDBU+][TFEÀ]-
catalyzed reaction of CO2 with 2-aminobenzonitrile to give
quinazoline-2,4(1H,3H)-dione (E) is proposed (Scheme 2). In
[HDBU+][TFEÀ], 2-aminobenzonitrile is activated by hydro-
gen bonding with both the cation and anion of the IL to form
the intermediate A, while CO2 is activated by the anion
[TFEÀ] to form the intermediate B. The nucleophilic nitrogen
atom of A attacks the carbon atom of B to form the
intermediate C, with subsequent nucleophilic cyclization of C
to produced D, which is subsequently converted into E after
regeneration of [HDBU+][TFEÀ].
=
vibration of the C O bond of carbonate, thus confirming the
formation of carbonate and the 13C NMR data. This carbon-
ate may be the key intermediate for the CO2 conversion.
The 1H, 13C, and 15N NMR analyses for [HDBU+][TFEÀ],
2-aminobenzonitrile, and their mixture were carried out. The
1H NMR signal of the NH2 of 2-aminobenzonitrile in the
mixture shifted from d = 5.98 (the shift of NH2 in pure 2-
aminobenzonitrile) to 6.03 ppm, and showed broadening (see
Figure S6 in the Supporting Information), thus suggesting the
hydrogen bonding between the IL and the substrate. In
contrast, all the 15N NMR signals assigned to the N atoms of
the IL and 2-aminobenzonitrile shifted accordingly upon the
mixing these two compounds (Figure 2). Specifically, the
15N NMR signals for NH2 of 2-aminobenzonitrile and for NH
of [HDBU+] shifted significantly, thus indicating the hydro-
gen bonding between [HDBU+] and the substrate. Consider-
ing that [Et-DBU+][TFEÀ] afforded a much lower yield of
quinazoline-2,4(1H,3H)-dione as compared with [HDBU+]
[TFEÀ] (Table 1, entries 2 and 5), it can be deduced that the
In summary, a bifunctional IL catalyst, [HDBU+][TFEÀ],
was designed by neutralization of a superbase (DBU) and
a weak proton donor (trifluoroethanol), and found to activate
CO2 and 2-aminobenzonitriles simultaneously to produce
quinazoline-2,4(1H,3H)-diones in excellent yields under
atmospheric pressure at room temperature. In addition, this
Angew. Chem. Int. Ed. 2014, 53, 1 – 5
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

.
Angewandte
Communications
Beller, Angew. Chem. 2013, 125, 9747; Angew. Chem. Int. Ed.
2013, 52, 9568; g) S. Kikuchi, K. Sekine, T. Ishida, T. Yamada,
Angew. Chem. 2012, 124, 7095; Angew. Chem. Int. Ed. 2012, 51,
6989; h) B. Yu, H. Y. Zhang, Y. F. Zhao, S. Chen, J. L. Xu, L. D.
Hao, Z. M. Liu, ACS Catal. 2013, 3, 2076; i) B. Yu, Y. F. Zhao,
H. Y. Zhang, J. L. Xu, L. D. Hao, X. Gao, Z. M. Liu, Chem.
Commun. 2014, 50, 2330.
[5] a) C. J. Whiteoak, N. Kielland, V. Laserna, E. C. Escudero-
Adꢀn, E. Martin, A. W. Kleij, J. Am. Chem. Soc. 2013, 135, 1228;
b) M. S. Jeletic, M. T. Mock, A. M. Appel, J. C. Linehan, J. Am.
Chem. Soc. 2013, 135, 11533; c) A. H. Liu, R. Ma, C. Song, Z. Z.
Yang, A. Yu, Y. Cai, L. N. He, Y. N. Zhao, B. Yu, Q. W. Song,
Angew. Chem. 2012, 124, 11468; Angew. Chem. Int. Ed. 2012, 51,
11306; d) K. Sasano, J. Takaya, N. Iwasawa, J. Am. Chem. Soc.
2013, 135, 10954; e) A. Schꢁfer, W. Saak, D. Haase, T. Mꢂller,
Angew. Chem. 2012, 124, 3035; Angew. Chem. Int. Ed. 2012, 51,
2981; f) B. Chatelet, L. Joucla, J. P. Dutasta, A. Martinez, K. C.
Szeto, V. Dufaud, J. Am. Chem. Soc. 2013, 135, 5348; g) T.
Kimura, K. Kamata, N. Mizuno, Angew. Chem. 2012, 124, 6804;
Angew. Chem. Int. Ed. 2012, 51, 6700; h) Y. Xie, T. T. Wang,
X. H. Liu, K. Zou, W. Q. Deng, Nat. Commun. 2013, 4, 1960;
i) W. Y. Gao, Y. Chen, Y. H. Niu, K. Williams, L. Cash, P. J.
Perez, L. Wojtas, J. F. Cai, Y. S. Chen, S. Q. Ma, Angew. Chem.
2014, 126, 2653; Angew. Chem. Int. Ed. 2014, 53, 2615.
[6] a) J. L. Song, H. L. Fan, J. Ma, B. X. Han, Green Chem. 2013, 15,
2619; b) G. K. Cui, J. J. Zheng, X. Y. Luo, W. J. Lin, F. Ding,
H. R. Li, C. M. Wang, Angew. Chem. 2013, 125, 10814; Angew.
Chem. Int. Ed. 2013, 52, 10620.
Scheme 2. Possible reaction pathway.
IL could be easily recovered and reused without loss in its
activity. We believe that this kind of highly efficient, greener,
and stable bifunctional IL catalytic system is promising for
chemical fixation of CO2 and generation of various useful
chemicals under mild reaction conditions.
Received: January 17, 2014
Published online: && &&, &&&&
[7] a) C. M. Wang, X. Y. Luo, H. M. Luo, D. E. Jiang, H. R. Li, S.
Dai, Angew. Chem. 2011, 123, 5020; Angew. Chem. Int. Ed. 2011,
50, 4918; b) C. M. Wang, H. M. Luo, D. E. Jiang, H. R. Li, S. Dai,
Angew. Chem. 2010, 122, 6114; Angew. Chem. Int. Ed. 2010, 49,
5978; c) G. Gurau, H. Rodrꢃguez, S. P. Kelley, P. Janiczek, R. S.
Kalb, R. D. Rogers, Angew. Chem. 2011, 123, 12230; Angew.
Chem. Int. Ed. 2011, 50, 12024.
[8] a) T. P. Tran, E. L. Ellsworth, M. A. Stier, J. M. Domagala,
H. D. H. Showalter, S. J. Gracheck, M. A. Shapiro, T. E. Joan-
nides, R. Singh, Bioorg. Med. Chem. Lett. 2004, 14, 4405;
b) M. B. Andrus, S. N. Mettath, C. Song, J. Org. Chem. 2002, 67,
8284.
[9] a) T. Mizuno, N. Okamoto, T. Ito, T. Miyata, Tetrahedron Lett.
2000, 41, 1051; b) T. Mizuno, T. Iwai, Y. Ishino, Tetrahedron Lett.
2004, 45, 7073.
[10] Y. P. Patil, P. J. Tambade, S. R. Jagtap, B. M. Bhanage, Green
Chem. Lett. Rev. 2008, 1, 127.
[11] Y. P. Patil, P. J. Tambade, K. D. Parghi, R. V. Jayaram, B. M.
Bhanage, Catal. Lett. 2009, 133, 201.
[12] Y. P. Patil, P. J. Tambade, K. M. Deshmukh, B. M. Bhanage,
Catal. Today 2009, 148, 355.
[13] D. Nagai, T. Endo, J. Polym. Sci. Part A 2009, 47, 653.
[14] J. Gao, L. N. He, C. X. Miao, S. Chanfreau, Tetrahedron 2010, 66,
4063.
[15] T. Kimura, H. Sunaba, K. Kamataand, N. Mizuno, Inorg. Chem.
2012, 51, 13001.
Keywords: carbon dioxide fixation · heterocylces · ionic liquids ·
reaction mechanism · synthetic methods
.
[1] a) M. Y. He, Y. H. Sun, B. X. Han, Angew. Chem. 2013, 125,
9798; Angew. Chem. Int. Ed. 2013, 52, 9620; b) D. J. Dare-
nsbourg, Chem. Rev. 2007, 107, 2388.
[2] a) F. L. Liao, Y. Q. Huang, J. W. Ge, W. R. Zheng, K. Tedsree, P.
Collier, X. L. Hong, S. C. Tsang, Angew. Chem. 2011, 123, 2210;
Angew. Chem. Int. Ed. 2011, 50, 2162; b) S. Wesselbaum, T.
Stein, J. Klankermayer, W. Leitner, Angew. Chem. 2012, 124,
7617; Angew. Chem. Int. Ed. 2012, 51, 7499.
[3] a) D. Preti, C. Resta, S. Squarcialupi, G. Fachinetti, Angew.
Chem. 2011, 123, 12759; Angew. Chem. Int. Ed. 2011, 50, 12551;
b) Z. F. Zhang, Y. Xie, W. J. Li, S. Q. Hu, J. L. Song, T. Jiang,
B. X. Han, Angew. Chem. 2008, 120, 1143; Angew. Chem. Int. Ed.
2008, 47, 1127; c) S. Wesselbaum, U. Hintermair, W. Leitner,
Angew. Chem. 2012, 124, 8713; Angew. Chem. Int. Ed. 2012, 51,
8585.
[4] a) S. H. Kim, K. H. Kim, S. H. Hong, Angew. Chem. 2014, 126,
790; Angew. Chem. Int. Ed. 2014, 53, 771; b) B. Yu, H. Y. Zhang,
Y. F. Zhao, S. Chen, J. L. Xu, C. L. Huang, Z. M. Liu, Green
Chem. 2013, 15, 95; c) Y. Xie, K. L. Ding, Z. M. Liu, J. J. Li,
G. M. An, R. T. Tao, Z. Y. Sun, Z. Z. Yang, Chem. Eur. J. 2010,
16, 6687; d) Y. Xie, Z. F. Zhang, T. Jiang, J. L. He, B. X. Han,
T. B. Wu, K. L. Ding, Angew. Chem. 2007, 119, 7393; Angew.
Chem. Int. Ed. 2007, 46, 7255; e) T. Ohishi, L. Zhang, M.
Nishiura, Z. Hou, Angew. Chem. 2011, 123, 8264; Angew. Chem.
Int. Ed. 2011, 50, 8114; f) Y. H. Li, X. J. Fang, K. Junge, M.
[16] W. J. Lu, J. Ma, J. Y. Hu, J. L. Song, Z. F. Zhang, G. Y. Yang,
B. X. Han, Green Chem. 2014, 16, 221.
4
www.angewandte.org
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2014, 53, 1 – 5
These are not the final page numbers!

Angewandte
Chemie
Communications
Heterocycles
Y. F. Zhao, B. Yu, Z. Z. Yang, H. Y. Zhang,
L. D. Hao, X. Gao,
Z. M. Liu*
&&&& — &&&&
No pressure: The reaction of CO2 with
various 2-aminobenzonitriles was ach-
ieved at atmospheric pressure and room
temperature by using the bifunctional
protic ionic liquid [HDBU+][TFEÀ], thus
producing the title compounds in excel-
lent yields. The ionic liquid serves as both
A Protic Ionic Liquid Catalyzes CO2
Conversion at Atmospheric Pressure and
Room Temperature: Synthesis of
Quinazoline-2,4(1H,3H)-diones
the catalyst and solvent, and activates
both CO2 and the substrates simultane-
ously. DBU=1,8-diazabicyclo-
[5.4.0]undec-7-ene, TFE=trifluoroetha-
nol.
Angew. Chem. Int. Ed. 2014, 53, 1 – 5
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!