De novo synthesis of imidazoles by visible-light-induced photocatalytic aerobic oxidation/[3+2] cycloaddition/aromatization cascade

Article abstract of DOI:10.1002/asia.201402443

A visible-light-induced photocatalytic aerobic oxidation/[3+2] cycloaddition/aromatization cascade between secondary amines and isocyanides has been successfully developed. The reaction provides a general and efficient access to diversely substituted imidazoles and imidazo[1,5-a]quinoxalin-4(5 H)-ones in good yields under mild conditions.

Full text of DOI:10.1002/asia.201402443

COMMUNICATION
DOI: 10.1002/asia.201402443
De Novo Synthesis of Imidazoles by Visible-Light-Induced Photocatalytic
Aerobic Oxidation/ACTHNUTRGNE[UNG 3+2] Cycloaddition/Aromatization Cascade
Qiao-Hui Deng,[a] You-Quan Zou,[a] Liang-Qiu Lu,[a] Zi-Long Tang,[b]
Jia-Rong Chen,*[a] and Wen-Jing Xiao*[a, b]
Abstract: A visible-light-induced photocatalytic aerobic oxi-
dation/ACHTUNGTRENNUNG[3+2] cycloaddition/aromatization cascade between
secondary amines and isocyanides has been successfully de-
veloped. The reaction provides a general and efficient
access to diversely substituted imidazoles and imidazoACHTUNGTRENNUNG
a]quinoxalin-4ACHTUNGTRENNUNG
tions.
Over the past several years, visible-light-induced photore-
dox catalysis has enjoyed a remarkable renaissance and
found wide applications in organic synthesis.[1] The genera-
tion of diverse, highly reactive intermediates with distinctive
properties by this strategy has provided a powerful platform
for the design of new synthetic transformations and the con-
cise synthesis of complex target molecules.[2] In this context,
a diverse range of nucleophilic a-amino radicals as well as
electrophilic iminium ions and imines have been successfully
generated in situ by the visible-light-induced photocatalytic
activation of the corresponding amine precursors.[3] Further
transformations of these intermediates have resulted in the
facile construction and derivation of various nitrogen-con-
taining compounds. In a seminal publication by Stephenson
and co-workers in 2010, a photocatalytic cross-coupling of
nitroalkanes of tetrahydroisoquinolines has been disclosed
(Scheme 1a).[4] Subsequently, the groups of Rueping, Li, and
Wu have elegantly described a series of visible-light-promot-
Scheme 1. Reaction design.
ed functionalizations of secondary amines, in which the tran-
sient formation of imines and their interception by various
nucleophiles are usually involved.[5] In 2011, we developed
a visible-light-induced photocatalytic cascade reaction of tet-
rahydroisoquinoline esters with electron-deficient alkenes
and alkynes, efficiently affording pyrroloACTHNUTRGNEUGN[2,1-a]isoquinoline
derivatives (Scheme 1b).[6] Despite these advances, to our
knowledge, the visible-light-induced photocatalytic sequen-
tial generation of imines and application of these reactive
intermediates to cycloaddition as “2-atom synthon” have
never been explored.
[a] Q.-H. Deng, Y.-Q. Zou, Dr. L.-Q. Lu, Dr. J.-R. Chen,
Prof. Dr. W.-J. Xiao
Key Laboratory of Pesticide&Chemical Biology
Ministry of Education
College of Chemistry
Central China Normal University
152 Luoyu Road, Wuhan, Hubei 430079 (China)
Collaborative Innovation Centre of Chemical Science and Engineer-
ing
Tianjin 300072 (China)
Fax : (+86)27-6786-2041
E-mail: chenjiarong@mail.ccnu.edu.cn
wxiao@mail.ccnu.edu.cn
Homepage: http://chem-xiao.ccnu.edu.cn
On the other hand, highly functionalized imidazoles rep-
resent an important class of heteroaromatic compounds with
broad applications in the construction of bioactive com-
pounds and pharmaceuticals as well as in asymmetric syn-
thesis.[7] Among them, the 1,5-disubstituted imidazole deriv-
atives are of great interest to both medicinal and synthetic
chemists because of their unique structure and biological
profile.[8] In addition, 1-arylimidazole-5-carboxylic esters
have been identified as important building blocks for the
synthesis of various herbicides, fungicides, and plant growth
regulators.[9,10] Not surprisingly, considerable research efforts
have been devoted towards the development of efficient
methods for their synthesis. Traditionally, the 1,5-disubstitut-
ed imidazole scaffolds can be prepared by transition metal-
catalyzed arylations of 1-aryl-1H-imidazoles with aryl hal-
[b] Prof. Dr. Z.-L. Tang, Prof. Dr. W.-J. Xiao
School of Chemistry and Chemical Engineering
Hunan University of Science and Technology
Xiangtan 411201 (China)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201402443.
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Wen-Jing Xiao, Jia-Rong Chen et al.
Table 1. Optimization of reaction conditions.[a]
ides[11,12] or by cycloadditions of corresponding tosylmethyl
isocyanides with imines.[13,14] However, many of these meth-
ods have been limited to specific substrate classes, harsh re-
action conditions, and sometimes long reaction times.[12,14]
Accordingly, it is still highly desirable to search for more ef-
ficient and operationally simple processes for the rapid syn-
thesis of diversely functionalized 1,5-disubstituted imidazole
derivatives.
As part of our ongoing research program on the synthesis
of biologically and synthetically important nitrogen-contain-
ing heterocycles by photocatalysis,[15] we recently achieved
a visible-light-induced phtotocatalytic aerobic oxidation/
TRENNUNG[3+2] cycloaddition/aromatization cascade between secon-
dary amines and isocyanides (Scheme 1c). In this Communi-
cation, we describe the corresponding preliminary results.
The photocatalytic reaction sequence that we have de-
signed is shown in Scheme 2. As described by Rueping and
ACHTUNG-
Entry
Photocatalyst
Base
Solvent
t [h]
Yield [%][b]
1
2
3
4
5
6
7
A
B
C
A
A
A
A
A
–
K2CO3
K2CO3
K2CO3
KOH
NaHCO3
K2CO3
K2CO3
K2CO3
K2CO3
–
DMF
DMF
DMF
DMF
DMF
DMSO
CH3CN
DMF
DMF
DMF
DMF
24
24
24
24
24
24
24
11
24
24
24
79
62
36
7
trace
33
49
8[c]
9[e]
10[f]
11[g]
82 (78[d]
trace
trace
0
)
A
A
K2CO3
[a] Unless noted otherwise, reactions were performed with 1a
(0.3 mmol), 2a (0.45 mmol), catalyst (1 mol%), base (0.6 mmol) in the
solvent (3.0 mL) under irradiation with an 18 W fluorescent bulb.
[b] Yield determined by GC using biphenyl as an internal standard.
[c] With 1.0 equiv of K2CO3. [d] Isolated yield. [e] Without photocatalyst.
[f] Without K2CO3. [g] Without visible light.
Scheme 2. Proposed mechanism.
some inorganic bases (KOH, NaHCO3) and solvents were
Li,[5] readily accessible secondary amines, such as glycine de-
rivatives 1, could undergo a photocatalytic oxidation to gen-
erate imine B in the presence of photocatalysts under the ir-
radiation of visible light. The imine B would react with the
isocyanides 2 through a formal [3+2] cycloaddition reaction
to afford the intermediate C, which then undergoes a proton
transfer/aromatization cascade to produce 1,5-disubstituted
imidazoles 3. In principle, this strategy would avoid the
preparation of moisture-sensitive imines and allow for effi-
cient incorporation of various functional groups into 1,5-po-
sitions on imidazole scaffolds.
also tested. It was found that the combination of Ir
ACHTUNGTRENNUNG(ppy)2
AHCTUNTGERN(GNUN bpy)PF6 with 1 equivalent of K2CO3 in DMF gave rise to
the optimal results and 3a was isolated in 78% yield
(Table 1, entry 8). To confirm that the reaction was indeed
mediated by visible-light-induced photocatalytic activation,
control experiments without photocatalyst, base or visible-
light were carried out. As expected, it was found that almost
no reaction occurred in the control reactions (Table 1, en-
tries 9–11).
With the optimal reaction conditions established, the
scope of this protocol was next investigated. This visible-
light photocatalytic cascade reaction seems quite tolerant
with respect to the ester moiety in the substrate 1. As shown
To examine the feasibility of the designed reaction, we in-
itially investigated the reaction of glycine-derived amine 1a
À
À
À
and tosylmethyl isocyanide 2a in the presence of Ir
A
N
in Scheme 3, variation of the CO2Et group to CO2Me,
À
À
CO2iPr, CO2Bn, and CO2tBu had no significant effect on
the reaction efficiency, and the reaction generally afforded
the corresponding products 3a-3e in good isolated yields
(Scheme 3, 52–86%). In addition, substituent variation at
the aromatic ring of arylglycine derivatives could also be
carried out. Note that electron-donating (Me, OMe) and
electron-withdrawing (Cl, Br) groups could be well incorpo-
rated on the benzene ring at ortho, meta and para positions,
thereby providing the corresponding imidazoles 3 f–3l in
51–82% yields. The substrate bearing the naphthyl group on
nitrogen could also participate in the reaction to give a mod-
erate yield of the product 3m. Importantly, in addition to
air using a fluorescent bulb (18 W) as the visible-light
source. To our delight, the reaction did indeed work, and
the desired product 1-arylimidazole-5-carboxylate 3a was
obtained in 79% yield (as assessed by GC) after 24 h
(Table 1, entry 1). Encouraged by this preliminary result,
other reaction parameters such as different photocatalysts,
bases, and solvents were then examined to increase the reac-
tion efficiency, and the representative results are highlighted
in Table 1.[16] A brief screen of commonly used photocata-
lysts showed that IrACHTNUTRGENN(UG ppy)2CAHTUNGTNER(NUGN bpy)PF6 was the best of choice
(Table 1, entries 1–3). With the use of IrACHTNUTRGENNUG(ppy)2ACHTUNGTNER(NUGN bpy)PF6,
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Wen-Jing Xiao, Jia-Rong Chen et al.
Scheme 4. Synthetic applications.
In summary, we have developed a visible-light-induced
photocatalytic aerobic oxidation/[3+2] cycloaddition/aroma-
AHCTUNGTRENNUNG
tization cascade between secondary amines and isocyanides.
The reaction provides a facile access to a series of biologi-
cally significant 1,5-disubstituted imidazoles. The readily
availability of the starting materials, simple operation, and
mild reaction conditions make this protocol attractive to
both organic and medicinal chemists. Further detailed mech-
anistic investigation of this reaction and applications to the
synthesis of other heterocycles are currently underway in
our laboratory.
Experimental Section
General procedure: Glycine derivative 1a (0.50 mmol, 96.62 mg), tosyl-
methyl isocyanide 2a (0.75 mmol, 146.43 mg), IrACTHNUTRGNEN(UG ppy)2ACHTUNGTRENNUNG(bpy)PF6
Scheme 3. Examination of the substrate scope. All yields given corre-
spond to isolated yields.
(0.005 mmol, 4.01 mg), K2CO3 (0.50 mmol, 68.96 mg) and dry DMF
(5.0 mL) were added to a 10 mL Schlenk tube equipped with a magnetic
stir bar. Subsequently, the reaction mixture was stirred under irradiation
with a 18 W fluorescent bulb under air. The reaction was monitored by
thin-layer chromatography (TLC, (petroleum ether/EtOAc 4:1). Upon
complete consumption of the starting materials, the reaction mixture was
quenched with distilled water (15.0 mL). The resultant mixture was ex-
tracted with Et2O, and the combined organic layers were dried over
Na2SO4. After removal of the solvent in vacuum, the residue was purified
by flash chromatography on silica gel (EtOAc/petroleum ether 1:4) to
give the desired product 3a as a white solid in 78% yield.
glycine-derived amines, a-amino-substituted ketones with
weak electron-donating (Me) or electron-withdrawing (Cl)
groups on the aromatic ring also proved to be suitable for
this transformation, and the corresponding products 3n–3p
were obtained in 42–59% yields. Furthermore, 1,4,5-trisub-
stituted imidazole 3q can also be synthesized in a yield of
45% with the use of a-tosylmethyl isocyanide (R3 =Me) as
the substrate. Attempts to vary the substituent at the C4-po-
sition in 1,4,5-trisubstituted imidazoles (with groups other
than methyl or H) failed, presumably due to steric hin-
drance.[17]
To demonstrate the preparative utility of this process, we
conducted the reaction between 1a (1.35 g) and 2a (2.05 g)
in the presence of IrACHTUNRTGENN(UG ppy)2ACHTUNTGNER(NGUN bpy)PF6 (1 mol%) on a gram
scale [Scheme 4, Eq. (1)]. Gratifyingly, the desired product
3a (1.21 g) was isolated in 75% yield. Perhaps more impor-
tantly, this photocatalytic cascade reaction has been success-
fully applied to the synthesis of the biologically useful 5-
Acknowledgements
We are grateful to the National Science Foundation of China (Nos.
21232003, 21272087, and 21202053) and the National Basic Research Pro-
gram of China (2011CB808603) for support of this research. Y.-Q. Zou.
thanks the Excellent Doctorial Dissertation Cultivation Grant from Cen-
tral China Normal University (CCNU13T04094, 2013YBZD22).
Keywords: cascade · cycloaddition · imidazoles · oxidation ·
photochemistry
methylimidazo
ACHTUNGTRENNUNG[1,5-a]quinoxalin-4ACTHUNGTRENNUNG
methoxybenzyl) imidazo [1,5-a]quinoxalin-4ACHTUNGTRENNUNG
[Scheme 4, Eq. (2)]. Removal of the p-methoxybenzyl
(PMB) protecting group of 5b according to a literature pro-
cedure would deliver the corresponding imidazoACTHNUTRGNE[UNG 1,5-a]qui-
[1] For selected reviews, see: a) K. Zeitler, Angew. Chem. Int. Ed. 2009,
48, 9785–9789; Angew. Chem. 2009, 121, 9969–9974; b) T. P. Yoon,
M. A. Ischay, J. Du, Nat. Chem. 2010, 2, 527–532; c) J. M. R. Nar-
ayanam, C. R. J. Stephenson, Chem. Soc. Rev. 2011, 40, 102–113;
d) J. W. Tucker, C. R. J. Stephenson, J. Org. Chem. 2012, 77, 1617–
noxalin-4-one 6, which is a novel protein tyrosine kinase
(PTK) inhibitor candidate.[18]
3
&
&
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ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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www.chemasianj.org
Wen-Jing Xiao, Jia-Rong Chen et al.
1622; e) J. Xuan, W.-J. Xiao, Angew. Chem. Int. Ed. 2012, 51, 6828–
6838; Angew. Chem. 2012, 124, 6934–6944; f) N. Zheng, S. Maity,
Synlett 2012, 1851–1856; g) Y. Xi, H. Yi, A. Lei, Org. Biomol.
Chem. 2013, 11, 2387–2403; h) C. K. Prier, D. A. Rankic, D. W. C.
MacMillan, Chem. Rev. 2013, 113, 5322–5363; i) T. Koike, M. Akita,
Top. Catal. 2014, 1, DOI: 10.1007s11244-014-0259-7; j) D. M. Schultz,
T. P. Yoon, Science 2014, 343, DOI: 10.1126/science.1239176;
k) M. N. Hopkinson, B. Sahoo, J.-L. Li, F. Glorius, Chem. Eur. J.
2014, 20, 3874–3886.
[9] a) T. Maier, R. Schmierer, K. Bauer, H. Bieringer, H. Buerstell, B.
Sachse, US Patent 4820335A, April 11, 1989; Chem. Abstr. 1989,
111, 19494–19501; b) T. Maier, R. Schmierer, K. Bauer, H. Biering-
er, H. Buerstell, B. Sachse, DE 3217094A1, November 10, 1983;
Chem. Abstr. 1984, 100, 85699–85724.
[10] a) R. Schmiere, H. Mildenberger, H. Buerstell, DE 3614364A1, Oc-
tober 29, 1987; Chem. Abstr. 1988, 108, 37838–37849; b) E. F.
Schulze, H. Buerstell, E. Hacker, EP 0167776A1, January 15, 1986;
Chem. Abstr. 1986, 104, 125061–125074.
[2] Y.-Q. Zou, J.-R. Chen, W.-J. Xiao, Angew. Chem. Int. Ed. 2013, 52,
11701–11703; Angew. Chem. 2013, 125, 11917–11919.
[11] a) D. Alberico, M. E. Scott, M. Lautens, Chem. Rev. 2007, 107, 174–
238; b) I. V. Seregin, V. Gevorgyan, Chem. Soc. Rev. 2007, 36, 1173–
1193; c) F. Bellina, S. Cauteruccio, R. Rossi, Curr. Org. Chem. 2008,
12, 774–790.
[12] F. Bellina, S. Cauteruccio, L. Mannina, R. Rossi, S. Viel, J. Org.
Chem. 2005, 70, 3997–4005.
[3] For selected reviews, see: a) L. Shi, W. Xia, Chem. Soc. Rev. 2012,
41, 7687–7697; b) J. Hu, J. Wang, T. H. Nguyen, N. Zheng, Beilstein
J. Org. Chem. 2013, 9, 1977–2001; c) J. Xie, H.-M. Jin, P. Xu, C.-J.
Zhu, Tetrahedron Lett. 2014, 55, 36–48; for selected examples on
photochemical oxidations of amines and their synthetic applications,
see: d) D. B. Freeman, L. Furst, A. G. Condie, C. R. Stephenson,
Org. Lett. 2012, 14, 94–97; e) M. Rueping, S. Zhu, R. M. Koenigs,
Chem. Commun. 2011, 47, 12709–12711; f) M. Rueping, S. Zhu,
R. M. Koenigs, Chem. Commun. 2011, 47, 8679–8681; g) M. Ruep-
ing, C. Vila, R. M. Koenigs, K. Poscharny, D. C. Fabry, Chem.
Commun. 2011, 47, 2360–2362; h) M. Rueping, D. Leonori, T. Pois-
son, Chem. Commun. 2011, 47, 9615–9617; i) M. Rueping, R. M.
Koenigs, K. Poscharny, D. C. Fabry, D. Leonori, C. Vila, Chem. Eur.
J. 2012, 18, 5170–5174; j) M. Rueping, J. Zoller, D. C. Fabry, K. Pos-
charny, R. M. Koenigs, T. E. Weirich, J. Mayer, Chem. Eur. J. 2012,
18, 3478–3481; k) D. P. Hari, B. Kçnig, Org. Lett. 2011, 13, 3852–
3855; l) F. Su, S. C. Mathew, L. Mçhlmann, M. Antonietti, X. Wang,
S. Blechert, Angew. Chem. Int. Ed. 2011, 50, 657–660; Angew.
Chem. 2011, 123, 683–686; m) Z. Xie, C. Wang, K. E. deKrafft, W.
Lin, J. Am. Chem. Soc. 2011, 133, 2056–2059; n) Y. Miyake, K. Na-
kajima, Y. Nishibayashi, J. Am. Chem. Soc. 2012, 134, 3338–3341;
o) Q.-Y. Meng, J.-J. Zhong, Q. Liu, X.-W. Gao, H.-H. Zhang, T. Lei,
Z.-J. Li, K. Feng, B. Chen, C.-H. Tung, L.-Z. Wu, J. Am. Chem. Soc.
2013, 135, 19052–19055.
[13] For selected reviews, see: a) U. Schçllkopf, Angew. Chem. Int. Ed.
Engl. 1977, 16, 339–348; Angew. Chem. 1977, 89, 351–360; b) D.
Hoppe, Angew. Chem. Int. Ed. Engl. 1974, 13, 789–804; Angew.
Chem. 1974, 86, 878–893; c) A. Dçmling, I. Ugi, Angew. Chem. Int.
Ed. 2000, 39, 3168–3210; Angew. Chem. 2000, 112, 3300–3344;
d) A. Dçmling, Chem. Rev. 2006, 106, 17–18; e) A. V. Gulevich,
A. G. Zhdanko, R. V. Orru, V. G. Nenajdenko, Chem. Rev. 2010,
110, 5235–5331; f) J.-P. Zhu, Eur. J. Org. Chem. 2003, 1133–1144;
g) D. Van Leusen, A. M. Van Leusen, Org. React. 2001, 57, 417–666;
h) I. Kumar, RSC Adv. 2014, 4, 16397–16408.
[14] a) B. C. Chen, M. S. Bednarz, R. Zhao, J. E. Sundeen, P. Chen, Z.
Shen, A. P. Skoumbourdis, J. C. Barrish, Tetrahedron Lett. 2000, 41,
5453–5456; b) A. M. van Leusen, J. Wildeman, O. H. Oldenziel, J.
Org. Chem. 1977, 42, 1153–1159; c) J. Sisko, A. J. Kassick, M. Mel-
linger, J. J. Filan, A. Allen, M. A. Olsen, J. Org. Chem. 2000, 65,
1516–1524.
[15] For a recent review, see: a) J. Xuan, L.-Q. Lu, J.-R. Chen, W.-J.
Xiao, Eur. J. Org. Chem. 2013, 6755–6770; For related examples
from our group, see: b) J. Xuan, Y. Cheng, J. An, L.-Q. Lu, X.-X.
Zhang, W.-J. Xiao, Chem. Commun. 2011, 47, 8337–8339; c) J.
Xuan, Z.-J. Feng, S.-W. Duan, W.-J. Xiao, RSC Adv. 2012, 2, 4065–
4068.
[4] A. G. Condie, J. C. Gonzalez-Gomez, C. R. J. Stephenson, J. Am.
Chem. Soc. 2010, 132, 1464–1465.
[5] a) S. Zhu, M. Rueping, Chem. Commun. 2012, 48, 11960–11962;
b) Z.-Q. Wang, M. Hu, X.-C. Huang, L.-B. Gong, Y.-X. Xie, J.-H. Li,
J. Org. Chem. 2012, 77, 8705–8711; c) X.-W. Gao, Q.-Y. Meng, M.
Xiang, B. Chen, K. Feng, C.-H. Tung, L.-Z. Wu, Adv. Synth. Catal.
2013, 355, 2158–2164.
[16] Please see the Supporting Information for more details on optimiza-
tion studies.
[17] a) F. De Moliner, C. Hulme, Tetrahedron Lett. 2012, 53, 5787–5790;
b) R. Wang, X.-P. Xu, H. Meng, S.-Y. Wang, S.-J. Ji, Tetrahedron
2013, 69, 1761–1766.
[6] Y.-Q. Zou, L.-Q. Lu, L. Fu, N.-J. Chang, J. Rong, J.-R. Chen, W.-J.
Xiao, Angew. Chem. Int. Ed. 2011, 50, 7171–7175; Angew. Chem.
2011, 123, 7309–7313.
[7] For selected reviews, see: a) F. Bellina, R. Rossi, Adv. Synth. Catal.
2010, 352, 1223–1276; b) S. Kamijo, Y. Yamamoto, Chem. Asian J.
2007, 2, 568–578; c) C. Lovely, H. Du, Y. He, R. Sivappa, Synlett
2006, 7, 0965–0992; d) F. Bellina, S. Cauteruccio, R. Rossi, Tetrahe-
dron 2007, 63, 4571–4624.
[8] a) L. Wang, K. W. Woods, Q. Li, K. J. Barr, R. W. McCroskey, S. M.
Hannick, L. Gherke, R. B. Credo, Y. H. Hui, K. Marsh, R. Warner,
J. Y. Lee, N. Zielinski-Mozng, D. Frost, S. H. Rosenberg, H. L.
Sham, J. Med. Chem. 2002, 45, 1697–1711; b) F. Bellina, S. Cauter-
uccio, S. Monti, R. Rossi, Bioorg. Med. Chem. Lett. 2006, 16, 5757–
5762; c) F. Bellina, S. Cauteruccio, A. Di Fiore, R. Rossi, Eur. J.
Org. Chem. 2008, 5436–5445.
[18] a) E. J. Jacobsen, L. S. Stelzer, K. L. Belonga, D. B. Carter, W. B. Im,
V. H. Sethy, A. H. Tang, P. F. VonVoigtlander, J. D. Petke, J. Med.
Chem. 1996, 39, 3820–3836; b) D. D. Davey, P. W. Erhardt, E. H.
Cantor, S. S. Greenberg, W. R. Ingebretsen, J. Wiggins, J. Med.
Chem. 1991, 34, 2671–2677; c) V. Colotta, L. Cecchi, D. Catarzi, G.
Filacchioni, C. Martini, P. Tacchi, A. Lucacchini, Eur. J. Med. Chem.
1995, 30, 133–139; d) J. Ohmori, M. Shimizu-Sasamata, M. Okada,
S. Sakamoto, J. Med. Chem. 1997, 40, 2053–2063; e) P. Chen, J. C.
Barrish, E. Iwanowicz, J. Lin, M. S. Bednarz, B.-C. Chen, Tetrahe-
dron Lett. 2001, 42, 4293–4295; f) B.-C. Chen, R. Zhao, M. S. Bed-
narz, B. Wang, J. E. Sundeen, J. C. Barrish, J. Org. Chem. 2004, 69,
977–979.
Received: March 27, 2014
Published online: && &&, 0000
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ÝÝ These are not the final page numbers!

COMMUNICATION
Photocatalysis
Qiao-Hui Deng, You-Quan Zou,
Liang-Qiu Lu, Zi-Long Tang,
Jia-Rong Chen,*
Wen-Jing Xiao*
&&&& — &&&&
A cascade of change: A visible-light-
induced photocatalytic aerobic oxida-
a general and efficient access to
diversely substituted imidazoles and
imidazoACTHNGUTRENN[UG 1,5-a]quinoxalin-4ACHTUNGRTEN(NUNG 5H)-ones
in good yields under very mild condi-
tions.
De Novo Synthesis of Imidazoles by
Visible-Light-Induced Photocatalytic
Aerobic Oxidation/ACTHNUGRTNEUNG[3+2] Cycloaddi-
tion/
N
cascade between secondary amines
and isocyanides has been successfully
developed. The reaction provides
tion/Aromatization Cascade
5
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Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ÞÞ