One-Pot Synthesis of p-Amino-Substituted Unsymmetrical Benzils and Benzil Derivatives

Article abstract of DOI:10.1002/adsc.201600389

An efficient iodine/copper(II) oxide co-promoted direct oxidative coupling of anilines and methyl aryl ketones has been developed for the synthesis of p-amino-substituted unsymmetrical benzils and their iodo-substituted derivatives. The chemoselectivity of the reactions can be easily controlled by adjusting the amount of iodine. This method exhibits good functional group tolerance for various substituents on the aromatic rings of the methyl aryl ketones. A possible mechanism for this reaction has been proposed based on control experiments. A couple of representative quinoxalines were synthesized from the benzil products in order to demonstrate the utility of this approach. (Figure presented.).

Full text of DOI:10.1002/adsc.201600389

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DOI: 10.1002/adsc.201600389
One-Pot Synthesis of p-Amino-Substituted Unsymmetrical
Benzils and Benzil Derivatives
Hongjin Zhang,a Xiangwei Ren,a Wentao Zhao,a,* Xiangyang Tang,a
and Guangwei Wanga,b,*
a
Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, Peopleꢀs Republic of China
Fax : (+86)-22-2740-3475; e-mail: wanggw@tju.edu.cn or wentao_zhao@tju.edu.cn
Tianjin Key Laboratory of Molecular Optoelectronic Science, Tianjin 300072, Peopleꢀs Republic of China
b
Received: April 12, 2016; Revised: November 6, 2016; Published online:&&
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201600389.
Abstract: An efficient iodine/copper(II) oxide co-
promoted direct oxidative coupling of anilines and
methyl aryl ketones has been developed for the syn-
thesis of p-amino-substituted unsymmetrical benzils
and their iodo-substituted derivatives. The chemo-
selectivity of the reactions can be easily controlled
by adjusting the amount of iodine. This method ex-
hibits good functional group tolerance for various
substituents on the aromatic rings of the methyl
aryl ketones. A possible mechanism for this reac-
tion has been proposed based on control experi-
ments. A couple of representative quinoxalines
were synthesized from the benzil products in order
to demonstrate the utility of this approach.
thesis of benzils with a free amine substituent are
very limited. In most cases, the synthesis of amine-
containing benzils occurs via functional group trans-
formations of the corresponding precursors by
making use of an amine precursor or a protected
amine. For example, the reduction of nitro-substituted
benzils,[7] the amination of halo-substituted benzils,[8]
or the removal of the amino protecting group can
lead to p-amino-substituted benzils [Eq. (6)].
There are only a few reported methods[9] that do
not require amine protection for the formation of
amine-containing diketones. For example, Cheng
et al. developed an oxidative process[9a] which con-
verts 1,2-diphenylalkynes to the corresponding dike-
tones in the presence of a free amine with moderate
yields. The Pd-catalyzed coupling of tetramethylam-
monium (pentacarbonyl)chromates with aryl iodides
in a CO atmosphere[9b] to give amine-containing ben-
zils has also been reported. However, this approach
has disadvantages such as the high cost and limited
availability of the substrates and catalysts. Thus the
Keywords: benzils; methyl aryl ketones; oxidative
coupling; quinoxalines; tandem reaction
1,2-Dicarbonyl derivatives are versatile structural straight-forward synthesis of amino-substituted benzil
motifs which are capable of undergoing various chem- derivatives is still a challenge to organic synthetic
ical transformations, especially for the synthesis of li- chemists and the development of an efficient ap-
gands[1] such as N-heterocyclic carbenes and diamines proach to access these compounds is highly desirable.
as well as biologically active heterocyclic com-
Recently, several iodine-mediated oxidative cou-
pounds[2] such as imidazoles and quinoxalines. In ad- plings of acetophenone with amines have been report-
dition, benzils and their derivatives exhibit various ed.[10] A plethora of aryl a-keto amides have been
biological activities such as carboxylesterase inhibi- conveniently synthesized by the oxidative coupling of
tion in mammals.[3] Some benzils are photosensitive styrene, phenylacetylene, or acetophenone with sec-
and can be used as photocurable coating agents.[4] As ondary amines.[11] However, only a few reports[10a,12]
shown in Scheme 1, benzils can be conveniently syn- have explored oxidative coupling reactions with pri-
thesized by oxidation of various precursors[5] such as mary amines. This is probably because the formation
2-hydroxy-1,2-diaryl-1-ethanones [Eq. (1)], 1,2-diaryl- of relative stable imine intermediate inhibits further
ACHTUNGTRENNUNGalkynes or alkenes [Eq. (2)], 1,2-diaryl-1-ethanones transformation of the intermediate to a-keto amides.
[Eq. (3)], and 1,2-dihalogenated 1,2-diarylethanes During our investigations of a one-pot synthetic pro-
[Eq. (4)]. Recently, Su et al. reported an efficient syn- tocol for a-keto amides from alkenes or alkynes,[13]
thesis for benzil derivatives which uses phenylhydra- we found that, when aniline was used, p-amino-substi-
zine and phenyl substituted alkenes [Eq. (5)].[6] How- tuted benzil was obtained instead of the correspond-
ever, straightforward synthetic methods for the syn- ing a-keto amide. This result prompted us to further
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Scheme 1. Synthetic routes for p-amino-substituted benzils.
explore this unexpected result. In this work, a highly
efficient, one-pot, oxidative coupling of methyl aryl
ketones with anilines to synthesize p-amino-substitut-
ed benzils and their iodo derivatives is reported.[14]
During the initial studies, the reaction between ace-
tophenone and aniline was selected as the model re-
action for optimizing the reaction conditions. Aceto-
phenone (1a, 1.0 equiv.) reacted with aniline (2a,
1.2 equiv.) and I2 (1.2 equiv.) in DMSO at 1008C for
12 h to give p-amino-substituted benzil (3aa) as the
major product with a moderate yield (45%, Table 1,
entry 1). No a-keto amide product was detected. The
reaction conditions were then optimized by varying
the ratio of aniline to acetophenone, the amount of
iodine, and the reaction temperature and the results
are shown in Table 1. Increasing the amount of I2 to
1.6 equiv. improved the conversion yield but the iodo-
product 4aa was obtained as a side product (Table 1,
entry 2). Increasing the amount of aniline to 1.6 equiv.
reduced the amount of iodo-product 4aa (Table 1,
entry 4), but further increasing the amount of aniline
did not improve the yield of target product 3aa.
In order to reduce the amount of iodine, various
additives were investigated and these results are also
shown in Table 1. Initially CuO was chosen as the ad-
ditive due to its good oxidative ability.[15] When
1 equiv. of I2 was used, the iodo-product 4aa was ob-
tained as a major product (entry 5). When the
amount of I2 was decreased to 0.6 equiv., the major
product 3aa was obtained in 59% yield (entry 7). Fur-
ther decreasing the amount of iodine did not lead to
a better result (entry 8). Other oxidative additives
were also tested. Neither TBHP (tert-butyl hydroper-
Table 1. Optimization of the reaction conditions.
Entry I2 [equiv.] 2a [equiv.] Additive
Yield [%][a]
3aa
4aa
1
2
3
4
5
6
7
8
1.2
1.6
1.6
1.6
1
1.2
1.2
1.4
1.6
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
none
none
none
none
CuO
CuO
CuO
CuO
CuO
56 (45)
–
40 (30) 43 (31)
54 (43) 18 (11)
66 (53) trace
27 (18) 43 (38)
47 (36) 25 (16)
73 (59)
68 (54)
56 (43)
51 (37)
65 (52)
38 (24)
45 (31)
–
0.8
0.6
0.5
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
0.6
–
–
–
–
–
–
–
–
–
–
–
–
–
9[b]
10[c]
11[d]
12
13
14
15
16
17
18
19
CuO
CuO
TBHP
DTBP
Oxone
MnO2
CuBr2
CuCl2
trace
68 (54)
63 (50)
Cu(OAc)2 58 (44)
CuI 63 (51)
[a]
The yields were determined by GC analysis. The values
in parenthesis are the isolated yields.
The reaction temperature was 1208C.
The reaction temperature was 1408C.
The reaction temperature was 908C.
[b]
[c]
[d]
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oxide) nor DTBP (di-tert-butyl peroxide) (entries 12 strates. Aryl methyl ketones with moderate or strong
and 13) gave better yields than CuO and the use of electron-withdrawing substituents (e.g., 4-Cl, 3-Cl, 2-
oxone resulted no desired product (entry 14). The Cl, 4-Br, and 4-NO2) on the phenyl rings were con-
metallic oxide MnO2 produced only trace amounts of verted into the corresponding benzil products in mod-
the desired product (entry 15). Other Cu salts were erate yields (52–62%, 3ba–3fa). In contrast, the aryl
also screened and the copper halides gave results sim- methyl ketone with an electron-donating group (4-
ilar to those for CuO (entries 16-19). A lower amount OMe) gave a lower yield (41%, 3ga). The steric effect
(0.6 equiv.) of CuO was also tested and a slightly was also investigated using substrates with substitu-
lower yield was obtained (66% vs. 73%).
tions at different positions of the phenyl ring (e.g., 2-
Different reaction temperatures were also investi- Me, 3-Me, 4-Me). These all gave moderate yields (53–
gated (Table 1, entries 7, and 9–11) and the best re- 58%, 3ha–3ka) indicating that the reaction is not sig-
sults were obtained at 1008C. Previously it had been nificantly affected by the steric properties of the aro-
shown that, at temperatures <708C, acetophenone matic ketone. In addition, 1- and 2-acetonaphthalene
(1a) is mainly converted to 2-(methylthio)-1,4-diphen- were converted to the expected products in moderate
yl-2-butene-1,4-dione in the presence of I2/CuO in yields (60–63%, 3la and 3ma). The optimized condi-
DMSO.[15a] This product is formed from the inter- tions were also applied to heteroaryl (such as pyridyl,
mediate 2-iodo-1-phenylethanone (1ac) and the in furanyl, and benzofuryl) ketones and the correspond-
situ generated dimethyl sulfide (DMS). Since DMS ing products were achieved in slightly lower yields
has a low boiling point (37.58C), a higher reaction (33–51%, 3na–3qa). Unfortunately, aliphatic methyl
temperature was used in these reactions in order to ketones including acetone, methyl ethyl ketone, and
decrease the amount of DMS in the reaction mixture methyl isopropyl ketone failed to give any of the ex-
and thus suppress the formation of these side prod- pected products.
ucts. Based on all these results, the optimized condi-
Subsequently, the scope of reaction for anilines was
tions were determined to be 1.6 equiv. of aniline to also investigated and these results are also shown in
acetophenone with CuO (1 equiv.) as the additive and Scheme 2. The anilines with electron-neutral groups
a reaction temperature of 1008C.
(e.g., 2-Me, 3-Me) gave the expected products in
With the optimized conditions in hand, the general- moderate yields (55–53%, 3ab–3ac). To further test if
ity and scope of the reaction were then investigated this transformation could occur at the ortho position
and the results are shown in Scheme 2. The reaction to the amino group in aniline, 4-methylaniline was
is applicable to a wide range of aromatic ketone sub- used under the same reaction conditions, but no cor-
Scheme 2. Scope of methyl ketones with anilines. Reaction conditions: 1 (1 mmol), 2 (1.2 mmol), and I2 (0.6 mmol) with CuO
(1 mmol) in DMSO (5 mL) at 1008C. The values in parenthesis are the isolated yields.
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responding o-acylated product was formed, indicating
In order to gain insights into the reaction mecha-
that this transformation does not occur at the ortho nism, several control experiments were conducted
position of the aniline. When an aniline bearing an and the results are shown in Scheme 4. According to
electron-withdrawing group (2-NO2) was applied to previously reported results,[15,17] acetophenone 1a can
this reaction, no expected products were obtained. easily be converted into 1ad and 1ae in high yields in
Therefore the electronic properties of the aniline play the presence of CuO, iodine, and DMSO [Scheme 4,
a key role in this reaction, and the reaction was not Eq. (1)]. When 1ad/1ae was combined with aniline 2a,
suitable for those anilines with electron-withdrawing and I2 in DMSO at 1008C, 3aa was obtained in 73%
substituents. N-Methylaniline was also investigated, yield [Eq. (2)]. This indicates that 1ad or 1ae might
but the major product was the diarylated product 6ab be the key intermediate for this reaction. On the
instead of the expected benzil product. Acetaniline other hand, at ambient temperature the reaction of
also was not suitable for this reaction.
aniline and a mixture of 1ad and 1ae (which were
During the above optimization of the one-pot reac- generated in situ from acetophenone 1a) afforded 5aa
tion conditions, o-iodoaniline 4aa was obtained as as the major product [Eq. (3)]. When I2 was added to
a minor product, which could serve as an important 5aa, it was further converted to 3aa with high yield in
building block for heterocyclic compounds.[16] There- DMSO at 1008C. In the absence of I2, only a trace
fore, reaction parameters were optimized for the syn- amount of 3aa was obtained. These results imply that
thesis of various iodo-derivatives. Based on the 3aa might be produced through intermediate 5aa and
screening experiments (see the Supporting Informa- that iodine plays a vital role in the formation of 3aa.
tion), increasing the amount of I2 to 3 equiv. improved
the yield of iodinated product to 53%.
There are two possible pathways for the formation
of intermediate 5aa and they are shown in Scheme 5.
The scope of the reaction for iodo-products was Path I is via the formation of imine 1af from the alde-
then investigated using these conditions (Scheme 3). hyde and aniline followed by a Friedel–Crafts reac-
Once again, the methyl ketones bearing electron-defi- tion with a second molecule of aniline. Path II is
cient groups were prone to give higher yields than the through a Friedel–Crafts reaction of aniline followed
ketones with electron-rich groups (e.g., 53%, 4fa vs. by a nucleophilic substitution with a second molecule
37%, 4ga). The acetonaphthalenes were also success- of aniline. In order to clarify which pathway domi-
fully converted to the expected products in moderate nates, imine 1af was synthesized through a known
yields (61–58%, 4ia–4ja). In addition, 3-pyridyl method[18] and then reacted with aniline. At room
methyl ketone could also give the corresponding temperature, 5aa was formed in very low yield but at
product with satisfactory yield (43%, 4ka).
an elevated temperature (1008C) a trace amount of
3aa was formed [Scheme 4, Eqs. (4) and (5)]. There-
fore, the formation of compound 5aa is probably
mainly via path II. In the presence of excessive
iodine, the iodo-product 4aa was formed from 3aa
[Scheme 4, Eq. (6)].
Based on the control experiments and previous re-
ports,[19]
a plausible mechanism is proposed in
Scheme 6. Initially, acetophenone 1a is converted into
intermediate A in the presence of I2/CuO and DMSO
by a Kornblum oxidation. As reported by Yin et al,[15]
CuO and DMSO can convert in situ generated HI
into iodine and realize a catalytic cycle for regenera-
tion of the iodine. Then a Friedel–Crafts-type reaction
between intermediate A and aniline affords com-
pound B which could be further converted to benzil
3aa through intermediate 5aa in the presence of
iodine. Although the conversion of 5aa to 3aa with
imine C as the intermediate has been confirmed, the
direct oxidation of B to 3aa cannot be ruled out.
When the amount of I2 is in excess, 3aa is further
transformed into the iodo-product 4aa.
As to the major formation of product 6ab from N-
methylaniline, it might involve a second Friedel–
Crafts reaction of intermediate Bꢀ with N-methylanili-
ne.[19b] The different reaction modes of aniline and N-
methylaniline are due to the nucleophilic competition
Scheme 3. Scope of iodo-products. Reaction conditions:
1 (1 mmol), 2a (1.2 mmol), and I2 (3 mmol) with CuO
(1 mmol) in DMSO (5 mL) at 1008C. The values in paren-
thesis are the isolated yields.
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Scheme 4. Control experiments for insights into the mechanism.
a by-product and in very low yield (<10%). In con-
trast, the N-methyl group is a better donating group
and less nucleophilic, which renders the second Frie-
del–Crafts reaction more favorable.
To demonstrate the importance and applicability of
this strategy, further transformations of the resulting
p-amino-substituted benzil derivatives were per-
formed. Quinoxalines occur widely in biologically
active compounds, functional materials, and drug mol-
ecules.[20] As illustrated in Scheme 7, quinoxalines 7a
and 7b were successfully synthesized from p-amino-
substituted benzils 3aa and 3ca with high efficiencies
(a 53% overall yield from the corresponding aceto-
phenones was achieved in two steps). Further trans-
formations of the iodo-benzil derivatives were also
achieved. For example, indole-quinoxaline derivative
8 was obtained in a 39% overall yield from acetophe-
none in three steps. This concise and highly efficient
method should be very useful for the synthesis of var-
ious p-amino-substituted benzils that are needed in
biological and pharmaceutical screening procedures.
In conclusion, a novel method has been developed
for the synthesis of p-amino-substituted unsymmetric
benzils and their derivatives from methyl aryl ketones
Scheme 5. Possible pathways for the formation of 5aa.
between the aromatic C-4 and the amino nitrogen. and anilines in the presence of I2, CuO, and DMSO.
For aniline, the amine is less steric hindered, so the These reactions proceed under mild conditions and
double alkylation product 6aa was formed only as are simple, efficient, and exhibit good functional
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Scheme 6. Plausible reaction pathways.
Experimental Section
Synthesis of 1-(4-Aminophenyl)-2-phenylethane-1,2-
dione (3aa); Representative Procedure I
A mixture of acetophenone 1a (120 mg, 1 mmol), CuO
(80 mg, 1 mmol) and iodine (152 mg, 0.6 mmol) in anhy-
drous DMSO (5 mL) was stirred at 1008C until 1a had dis-
appeared (monitored by thin layer chromatography). To the
above reaction mixture was added dropwise aniline 2a
(112 mg, 1.2 mmol) at room temperature and the solution
was then stirred at 1008C for 12 h. The reaction was
quenched with water, and then extracted with EtOAc (3ꢂ
20 mL). The combined organic layers were washed with sa-
turated Na2S2O3 solution, dried over anhydrous Na2SO4, and
concentrated. The residue was purified by column chroma-
tography on silica gel (petroleum ether/EtOAc=5:1) to
afford the desired product 3aa as a yellow solid; yield:
1
135 mg (59%); mp 128–1298C. H NMR (400 MHz, CDCl3):
d=7.96 (d, J=7.2 Hz, 2H), 7.77 (d, J=8.6 Hz, 2H), 7.62 (t,
J=7.4 Hz, 1H), 7.48 (t, J=7.7 Hz, 2H), 6.63 (d, J=8.8 Hz,
2H), 4.39 (s, 2H); 13C NMR (150 MHz, CDCl3): d=195.5,
192.7, 152.9, 134.6, 133.5, 132.7, 129.9, 128.9, 123.3, 114.0.
Scheme 7. Synthesis of quinoxaline derivatives.
Acknowledgements
group compatibility. The method may proceed via
a mechanism involving Kornblum oxidation, Friedel–
Crafts alkylation, oxidative dehydrogenation, and hy-
drolysis tandem processes. However, further studies
are needed to more fully elucidate the reaction mech-
anism. These studies along with the further develop-
ment of the synthetic applications of this strategy are
underway in our laboratory.
We thank the National Basic Research Program of China
(No. 2015CB856500) and the Natural Science Foundation of
Tianjin (No. 16 JCYBJC20100) for support of this research.
References
[1] a) L. Benhamou, E. Chardon, G. Lavigne, S. Bellemin-
Laponnaz, V. Cꢃsar, Chem. Rev. 2011, 111, 2705;
Adv. Synth. Catal. 0000, 000, 0 – 0
6
ꢁ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÞÞ
These are not the final page numbers!

COMMUNICATIONS
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b) E. J. Corey, D.-H. Lee, S. Sarshar, Tetrahedron:
Asymmetry 1995, 6, 3.
Ahmed, R. A. Vishwakarma, Org. Lett. 2014, 16, 1152;
d) R. Deshidi, M. Kumar, S. Devari, B. A. Shah, Chem.
Commun. 2014, 50, 9533.
[2] a) S. E. Wolkenberg, D. D. Wisnoski, W. H. Leister, Y.
Wang, Z. Zhao, C. W. Lindsley, Org. Lett. 2004, 6,
1453; b) S. Samanta, D. Roy, S. Khamarui, D. K. Maiti,
Chem. Commun. 2014, 50, 2477; c) D. Kumar, K. Seth,
D. N. Kommi, S. Bhagat, A. K. Chakraborti, RSC Adv.
2013, 3, 15157; d) M. Tingol, M. Mazzella, B. Panunz,
A. Tuzi, Eur. J. Org. Chem. 2011, 399.
[11] C. D. Risi, G. P. Pollini, V. Zanirato, Chem. Rev. 2016,
116, 3241.
[12] a) C. Zhang, N. Jiao, J. Am. Chem. Soc. 2010, 132, 28;
b) Z. Zhang, J. Su, Z. Zha, Z. Wang, Chem. Commun.
2013, 49, 8982; c) R. Deshidi, S. Devari, B. A. Shah,
Eur. J. Org. Chem. 2015, 1428; d) A. Sagadevan, A. Ra-
gupathi, C.-C. Lin, J. R. Hwu, K. C. Hwang, Green
Chem. 2015, 17, 1113; e) C. Zhang, X. Zong, L. Zhang,
N. Jiao, Org. Lett. 2012, 14, 3280.
[3] a) R. M. Wadkins, J. L. Hyatt, X. Wei, K. J. P. Yoon, M.
Wierdl, C. C. Edwards, C. L. Morton, J. C. Obenauer,
K. Damodaran, P. Beroza, M. K. Danks, P. M. Potter, J.
Med. Chem. 2005, 48, 2906; b) B. M. Young, J. L.
Hyatt, D. C. Bouck, T. Chen, P. Hanumesh, J. Price,
V. A. Boyd, P. M. Potter, T. R. Webb, J. Med. Chem.
2010, 53, 8709.
[13] X. Ren, G. Wang, X. Tang, W. Zhao, Chin. J. Org.
Chem. 2015, 35, 1733.
[14] During revision of this manuscript, a related work was
published: a) X. Wu, Q. Gao, X. Geng, J. Zhang, Y.-D.
Wu, A.-X. Wu, Org. Lett. 2016, 18, 2507; b) J.-C. Xiang,
Y. Cheng, M. Wang, Y.-D. Wu, A.-X. Wu, Org. Lett.
2016, 18, 4360.
[15] a) G. Yin, B. Zhou, X. Meng, A. Wu, Y. Pan, Org. Lett.
2006, 8, 2245; b) M. Gao, Y. Yang, Y.-D. Wu, C. Deng,
W.-M. Shu, D.-X. Zhang, L.-P. Cao, N.-F. She, A. Wu,
Org. Lett. 2010, 12, 4026.
[16] a) D. Ma, Q. Geng, H. Zhang, Y. Jiang, Angew. Chem.
2010, 122, 1313; Angew. Chem. Int. Ed. 2010, 49, 1291;
b) H. Deng, Z. Li, F. Ke, X. Zhou, Chem. Eur. J. 2012,
18, 4840; c) Q. Xing, H. Lv, C. Xia, F. Li, Chem. Eur. J.
2015, 21, 8591.
[17] a) Q. Gao, X. Wu, Y. Li, S. Liu, X. Meng, A. Wu, Adv.
Synth. Catal. 2014, 356, 2924; b) X. Wu, Q. Gao, S. Liu,
A. Wu, Org. Lett. 2014, 16, 2888; c) Y. Zhu, M. Liu, F.
Jia, J. Yuan, Q. Gao, M. Lian, A. Wu, Org. Lett. 2012,
14, 3392; d) K. K. D. R. Viswanadham, M. P. Reddy, P.
Sathyanarayana, O. Ravi, R. Kant, S. R. Bathula,
Chem. Commun. 2014, 50, 13517.
ˇ
ˇ
[4] a) B. Husꢄr, S. Commereuc, I. Lukꢄc, S. Chmela, J. M.
Nedelec, M. Baba, J. Phys. Chem. B. 2006, 110, 5315;
ˇ
ˇ
ˇ
ˇ
b) C. Kꢅsa, J. Mosnꢄcek, I. Lukꢄc, P. Hrdlovic, S.
Chmela, W. D. Habicher, J. Appl. Polym. Sci. 2006, 100,
4420.
[5] a) M. Weiss, M. Appel, J. Am. Chem. Soc. 1948, 70,
366; b) W. Ren, Y. Xia, S. J. Ji, Y. Zhang, X. Wan, J.
Zhao, Org. Lett. 2009, 11, 1841; c) H. Min, T. Palani, K.
Park, J. Hwang, S. Lee, J. Org. Chem. 2014, 79, 6279;
d) S. Chen, Z. Liu, E. Shi, L. Chen, W. Wei, H. Li, Y.
Cheng, X. Wan, Org. Lett. 2011, 13, 2274; e) B.
Schmidt, S. Krehl, S. Hauke, J. Org. Chem. 2013, 78,
5427; f) E. J. Corey, J. P. Schaefer, J. Am. Chem. Soc.
1960, 82, 918; g) J.-W. Yu, S. Mao, Y.-Q. Wang, Tetrahe-
dron Lett. 2015, 56, 1575; h) D. Villemin, M. Hammadi,
Synth. Commun. 1995, 25, 3145; i) C. Zhang, X. Wang,
N. Jiao, Synlett 2014, 25, 1458; j) W. Ren, J. Liu, L.
Chen, X. Wan, Adv. Synth. Catal. 2010, 352, 1424.
[6] Y. Su, X. Sun, G. Wu, N. Jiao, Angew. Chem. 2013, 125,
9990; Angew. Chem. Int. Ed. 2013, 52, 9808.
[18] a) E. Fraser, W. Paterson, G. R. Proctor, J. Chem. Soc.
1963, 5107; b) M.-Q. Jia, S.-L. You, ACS Catal. 2013, 3,
622.
[7] R. V. Jagadeesh, A.-E. Surkus, H. Junge, M.-M. Pohl, J.
Radnik, J. Rabeah, H. Huan, V. Schꢆnemann, A.
Brꢆckner, M. Beller, Science 2013, 342, 1073.
[19] a) Q. Gao, S. Liu, X. Wu, A. Wu, Org. Lett. 2014, 16,
4582; b) Y. Zhu, F. Jia, M. Liu, L. Wu, Q. Cai, Y. Gao,
A. Wu, Org. Lett. 2012, 14, 5378; c) Q. Gao, X. Wu, S.
Liu, A. Wu, Org. Lett. 2014, 16, 1732.
[20] a) H.-C. Chen, Y.-H. Chen, C.-C. Liu, Y.-C. Chien, S.-
W. Chou, P.-T. Chou, Chem. Mater. 2012, 24, 4766;
b) D. W. Chang, H. J. Lee, J. H. Kim, S. Y. Park, S.-M.
Park, L. Dai, J.-B. Baek, Org. Lett. 2011, 13, 3880; c) R.
Rajule, V. C. Bryant, H. Lopez, X. Luo, A. Natarajan,
Bioorg. Med. Chem. 2012, 20, 2227.
[8] a) K. Tiefenbacher, H. Dube, D. Ajami, D. Rebek Jr,
Chem. Commun. 2011, 47, 7341; b) H. Xu, C. Wolf,
Chem. Commun. 2009, 3035.
[9] a) X. Cheng, X. Li, W. Wan, W. Hao, L. Hai, Y. Wu,
Chem. Res. Chin. Univ. 2015, 31, 53; b) H. Sakurai, K.
Tanabe, K. Narasaka, Chem. Lett. 2000, 168.
[10] a) W. Wei, Y. Shao, H. Hu, F. Zhang, C. Zhang, Y. Xu,
X. Wan, J. Org. Chem. 2012, 77, 7157; b) X. Zhang, L.
Wang, Green Chem. 2012, 14, 2141; c) N. Mupparapu,
S. Khan, S. Battula, M. Kushwaha, A. P. Gupta, Q. N.
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COMMUNICATIONS
8 One-Pot Synthesis of p-Amino-Substituted Unsymmetrical
Benzils and Benzil Derivatives
Adv. Synth. Catal. 2017, 359, 1 – 8
Hongjin Zhang, Xiangwei Ren, Wentao Zhao,*
Xiangyang Tang, Guangwei Wang*
Adv. Synth. Catal. 0000, 000, 0 – 0
8
ꢁ 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÞÞ
These are not the final page numbers!