Unexpected C=N bond formation via NaI-catalyzed oxidative de-tetra-hydrogenative cross-couplings between N,N-dimethyl aniline and sulfamides

Article abstract of DOI:10.1039/c5ra06773a

A direct and convenient C=N bond formation reaction was reported, which was a de-tetra-hydrogenative cross-coupling (DTCC) reaction between N,N-dimethyl aniline and sulfamide under transition-metal-free conditions, and to give sulfonyl amidine derivatives in moderate to high yields.

Full text of DOI:10.1039/c5ra06773a

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: X. Xu, Y. Zheng, J.
Mao, J. Chen, G. Rong, D. Liu, H. Yan and Y. Chi, RSC Adv., 2015, DOI: 10.1039/C5RA06773A.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

Page 1 of 6
RSC Advances
View Article Online
DOI: 10.1039/C5RA06773A
TOC
A direct de-tetra-hydrogenative cross-coupling reaction between Csp3–H bond and sulfamide under transition-metal-free
condition is reported to give corresponding amidines.

Please do not adjust margins
RSC Advances
Page 2 of 6
View Article Online
DOI: 10.1039/C5RA06773A
Journal Name
COMMUNICATION
Unexpected C=N bond formation via NaI-catalyzed oxidative de-
tetra-hydrogenative cross-couplings between N, N-dimethyl
aniline and sulfamides
Received 00th January 20xx,
Accepted 00th January 20xx
Yang Zheng,a Jincheng Mao,*ab Jie Chen,a Guangwei Rong,a Defu Liu,a Hong Yan,a Yongjian Chia and
Xinfang Xu*a
DOI: 10.1039/x0xx00000x
www.rsc.org/
A direct and convenient C=N bonds formation reaction was
reported, which was de-tetra-hydrogenative cross-coupling
Previous work
a
R1
R2
R3
R1
R4
R5
R6
R4
R5
R6
[O]
[Cat.]
(DTCC) reaction between N, N-dimethyl aniline and sulfamide
under transition-metal-free condition, and to give sulfonyl
amidine derivatives in moderate to high yield.
/
R2
R3
C
H
H
C
(1)
(2)
(3)
+
+
+
C
C
_
2 H
R1
H
H
H
[O]
[Cu]
_
/
R1
N
N
R2
N
N
4 H
The cross-dehydrogenative coupling (CDC) has been proved a
powerful strategy in organic synthesis to form the C-C and C-X
bonds in recent years (Scheme 1, eq 1).1 However, formation of
double bond by removing four hydrogen atoms via twice CDCs is
still a great challenge because it is difficult to further remove
additional two hydrogen atoms after the single bond was formed
through the first CDC reaction. Recently, Jiao2a and Shi2b have
independently reported the pioneering works in constructing N=N
bond to synthesize aromatic azo compounds with copper catalyst
(Scheme 1, eq 2). Then, You and co-workers reported another
example of formation the C=C bond by palladium catalyzed de-
tetra-hydrogenative cross coupling (Scheme 1, eq 3).3 These reports
illuminate a new strategy to construct double bonds via CDC
reactions. Inspired by these works, here, we wish to report our
recent result on C=N bond formation between Csp3–H bond and
sulfamide by one-step DTCC reaction under transition-metal-free
conditions (Scheme 1, eq 4).
R2
R3
H
R1
H
R3
R4
/
H
H
[Pd] [O]
R1
R2
C
C
C
C
_
4 H
R2
R4
H
This work
H
H
H
H
R2
[O]
NaI
_
/
H
N
R2
C
R1
N
(4)
+
C
4 H
R1
H
Scheme 1 Various dehydrogenative cross-coupling reactions.
-metal catalyst via the reaction between sulfonamide and
formamide. However, formamide is also used as the solvent to
insure good conversion. In addition, aromatic formamides could not
be involved into the substrate scope because they are usually solid.
R2
A
Sulfonyl amidines are very unique motifs, which are important in
A
N
R3
6a
R2
O
H
Method C
O
medicinal and synthetic chemistry.
In recent years, many
Method A
O
N
synthetic methods have been developed (Scheme 2), including Li
(Method A),4 Chang (Method B),5 Wan (Method C),6a and others’
work6b-6d. However, sulfonyl azide was employed in the first two
reports, which was expensive and potentially explosive. In addition,
the metal catalyst was essential in these transformations. In
method C, product A could be achieved in the absence of transition-
R3
H
N
N
N
S
Ar
Ar
S
NH2
R1
O
O
H
N
H
R2
B
Method B
This work
A
R3
a.Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry,
Chemical Engineering and Materials Science, Soochow University, Suzhou
215123, P. R. China, E-mail: xinfangxu@suda.edu.cn.
O
O
S
b.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,
Southwest Petroleum University, Chengdu, 610500, P. R. China, E-mail:
jcmao@suda.edu.cn
R2
Ar
S
N
Ar
N
B =
NR2
A =
N
O
R1
R3
O
† Footnotes relaꢀng to the ꢀtle and/or authors should appear here.
Electronic Supplementary Information (ESI) available: [details of any
supplementary information available should be included here]. See
DOI: 10.1039/x0xx00000x
Scheme 2 Synthesis of sulfonyl amidines.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 3 of 6
View Article Online
DOI: 10.1039/C5RA06773A
COMMUNICATION
Journal Name
Table 2 NaI-catalyzed DTCC reactions a
Herein, we developed a novel strategy to access to sulfonyl
amidines with N, N-dimethyl aniline and sulfonamide, which
provides a direct method to synthesize various sulfonyl amidines
containing the structure of aromatic rings.4-6 Comparing to the sp3
C–H amination7 and above mentioned reports, this method could
be considered as a- powerful alternative strategy in direct C=N bond
formation.
R1
O
O
Ph
R
The optimization of catalytic system was summarized in Table 1.
Initially, various readily available catalysts were investigated (Table
1, entries 1-8) and NaI was found to be the best one (Table 1, entry
1). When the amount of 2a was increased, the yield of this
conversion was obviously promoted (Table 1, entry 1 vs entry 15).
Notably, the oxidant plays an important role in this reaction. As
shown in Table 1, anhydrous TBHP (5-6 M in decane) as the oxidant
was proved to be the best (80%, Table 1, entry 16), which is better
than TBHP (in water) did (65%, Table 1, entry 15). When other
oxidants were used, 3a can not be obtained (Table 1, entries 9-14).
In order to improve the catalytic effect, various additives were
employed into the reaction (Table 1, entries 17-19) and 1,10-phen-
anthroline (Phen) was best (Table 1, entry 17). Althoguh similar
transofmations assisted by organocatalysts have been present via
the radical intermediate,8 and the detailed mechanism is not very
clean yet. However, from the comparion experiments of with and
without the ligand, it indicates that the ligand assists the first part
S
S
Ph
N
N
N
N
O
O
R1 = 4-Me, 3j, 70%
R1 = 4-OMe, 3k, 65%
R1 = 4-F, 3l, 53%
R1 = 3-Br, 3m, 70%
R1 = 4-Cl, 3n, 60%
R1 = 4-Br, 3o, 70%
R1 = 4-acetamido, 3p, 40%
R1 = 4-CF3, 3q, 67%
R1 = 4-NO2, 3r, 54%
R = H, 3a, 70%
R = 4-Me, 3b, 32%
R = 4-F, 3c, 32%
R = 3-Br, 3d, 46%
R = 4-Br, 3e, 53%
R = 3-Cl, 3f, 51%
R = 2-Cl, 3g, 28%
R = 4-Cl, 3h, 33%
R = 4-NO2, 3i, 54%
R2 = 2-naphthyl, 3s, 60%
R2 = 2,4,6-trimethylbenzene, 3t, 80%
R2 = 2-thienyl, 3u, 60%
O
R2
S
Ph
N
N
O
a Reaction conditions: 1 (0.5 mmol), 2 (2.1 mmol), NaI (20 mol %), TBHP
(in decane, 1.5 mmol), Phen (0.05 mmol), EtOAc (2.0 mL), 80 oC, 12 h, air.
Isolated yield based on 1.
of the transformation, from materials to C.9
Table 1 Optimization of the reaction conditionsa
Under the optimized conditions, the substrates generality was
tested, and the results are shown in Table 2. Electron-donating
group (such as methyl) on the aniline gave slightly low yield (Table 2,
3b). While electron-withdrawing groups (such as fluoro, chloro,
bromo and nitro groups) on the aniline had different influence, and
yields of corresponding products 3 were obtained ranging from 28%
to 54%. Among these substitutents, bromo and nitro groups were
better than others (Table 2, 3d, 3e and 3i). m-Chloro group on the
aniline could also lead to the relatively good yield (Table 2, 3f). All in
all, we can see that N,N-dimethyl anilines without any substituents
on the aromatic ring gave the highest yield.
Yieldb
Entry
Cat.
Oxidant
Additive
(%)
40
1
2
NaI
—
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
TBHP
O2
—
—
ND
3
KI
—
35
4
TBAI
I2
—
31
Subsequently, the protocol was applied to the reaction with a
range of sulfonamides. To our delight, moderate to good yields
were acquired. Both electron-donating groups and electron-
withdrawing groups on the aromatic ring could be well tolerated
under this conditions (Table 2, 3j-3t). It is noteworthy that
heterocycle sulfonamides could give 3u with satisfying yield (60%).
To gain insight into the reaction mechanism, some additional
experiments have been performed as shown in Scheme 3. The
model reaction between 1a and 2a was performed under higher
temperature (110 oC) in the absence of Phen. 3a was obtained
together with many byproducts, which were generated from 2a
itself (Scheme 3, eq 1).10 This promoted us to conduct more
reactions between 1a and various anilines. When N-methyl aniline
was used instead of 2a, 3a could also be obtained with lower yield
and N-demethyl analog of 3a was not detected (Scheme 3, eq 2).
Then we tried to use aniline as the substrate. However, 3a or N-
demethyl analog of 3a was not acquired (Scheme 3, eq 3). In view
of above experiments, we can see that the methyl group of 3a
probably did not come from TBHP,11 and it is probably from N-
methyl aniline. 21b Next, benzyl-N,N-dimethylamine was employed.
5
—
11
6
PhI(OAc)2
CuI
—
trace
trace
trace
ND
7
—
8
FeCl3
NaI
—
9
—
10
11
12
13
14
15 c
16c,d
17 c,d
18 c,d
19 c,d
NaI
K2S2O8
H2O2
TBPB
DDQ
DCP
—
trace
ND
NaI
—
NaI
—
ND
NaI
—
ND
NaI
—
ND
NaI
TBHP
TBHP
TBHP
TBHP
TBHP
—
—
65
NaI
80
NaI
Phen
90(70)e
86(67)e
82(62)e
NaI
1H-Benzotriazole
TMEDA
NaI
a
Reaction conditions: benzene sulfonamide (1a, 0.5 mmol), N,N-dimethyl
aniline (2a, 0.7 mmol), catalyst (20 mol%), TBHP (70% aqueous solution,
1.5 mmol), additive (0.05 mmol, if added), toluene (2.0 mL), 110 oC, 12 h,
air; LC yield using an internal standard; c 2a (2.1 mmol), EtOAc (2.0 mL)
b
as the solvent, 80 C; TBHP (5-6 M in decane, 1.5 mmol); e Isolated yields
o
d
are given in parentheses.
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 4 of 6
View Article Online
DOI: 10.1039/C5RA06773A
Journal Name
COMMUNICATION
Scheme 5. Investigation of the reaction mechanism.
Therefore, it was assumed that the mechanism of the reaction
may proceed in a different pathway in our protocol. In
addition, it was found that with the base could not afford 3a
,
either. This may prove that it was not a schiff base-involved
reaction. Besides, the desired product was not detected when
the reaction was carried out in the presence of I2 and NaOH,
which could generate the hypoiodite species in situ and
catalyze the C–H functionalization.13a,13b Next, radical
scavengers like TEMPO or BHT (butylated hydroxytoluene) was
added to the reaction, and the reaction was inhibited (Scheme
5, eq 2). This suggested that the transformation probably
proceeded through a radical progress.
According to prior reports14 and above observation, a
plausible reaction mechanism is proposed in Scheme 6. In the
first step, TBHP was resolved to generate tert-butoxyl radical
and hydroxyl ion in associate with reduction of iodine ion.13
Scheme 3. Investigation of reactions between 1a and different amines.
To our surprise,the dephenylation coupling product N,N-dimethyl-
N‘-phenylsulfonyl)formimid-amide was afforded in 45% yield
(Scheme 3, eq 4).12 Other substrate were also tested, including N,N-
diethylaniline,
N-ethyl-N-methylaniline,
triethylamine,
and
trimethylamine, however, only very lower or no conversion was
observed. 9
Subsequently, aniline and benzamide were employed as the
substrates to react with 2a. However, the desired product could not
be generated under the standard condition when aniline was
employed as the substrate (Scheme 4, eq 1). And when benzamide
reacted with 2a, two products were afforded and the ratio was 3:2,
which determined by NMR. Interestingly, unexpected N-
methylformanilide was found here while it was not detected in the
model reaction between 1a and 2a (Scheme 4, eq 2). Without using
Phen, only N-[(methylanilino)methyl]benzamide was obtained with
higher yield of 34% (Scheme 4, eq 3).
Based on Wan’s work,6a 2a was possibly oxidized to N-methyl-N-
formyl-aniline by TBHP and then participated in the reaction. So we
directly used N-methyl-N-formyl-aniline as the substrate, and less
amount of desired product 3a was obtained (Scheme 5, eq 1).
Then tert-butoxyl radical abstracted a hydrogen atom from
2
to generate radical A, which subsequently formed iminium ion
B
through single electron transfer (SET) with iodine, and this
process was well studied and accepted in general15-21
Afterwards, benzene sulfonamide as a unique nucleophile
reagent16 attacked 17-26followed by deprotonation to form
B, C,
which was confirmed by HRMS and proton NMR.9 Sequentially
further oxidized by TBHP to produce the desired product
3 2,3,27
.
Scheme 6. Possible reaction pathways.
To our knowledge, various catalytic systems were developed
for synthesis of iminium ions from N,N-dialkylanilines. The
scope of catalysts includes Ru, 17 Rh,18 Ir,19 Cu,20 Fe,21 Mo,22
Au,23 Re,24 V25 and other complexes.26 However, NaI-catalyzed
reaction between N,N-dialkylaniline and TMSCN to transform
Scheme 4. Investigation of the reactions between 2a and aniline or
benzamide.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 5 of 6
View Article Online
DOI: 10.1039/C5RA06773A
COMMUNICATION
Journal Name
Cho and S. K. Han, J. Am. Chem. Soc., 2006, 128
12366−12367; (c) E. J. Yoo, I. Bea, S. H. Cho, H. Han and S.
Chang, Org. Lett., 2006, , 1347−1350; (d) J. Kim, S. Y. Lee, J.
,
iminium ions has never been reported. To our delight, 45%
yield of the target product was obtained as shown in Scheme
8
7, which will suggest that the corresponding iminium ion
the possible intermediate. 19,21,26
B was
Lee, Y. Do and S. Chang, J. Org. Chem., 2008, 73, 9454–9457.
(a) S. Chen, Y. Xu and X. Wan, Org. Lett., 2011, 13
6
7
,
6152−6155; (b) N. Liu, B.-Y. Tang, Y. Chen and L. He, Eur. J.
Org. Chem., 2009, 2059–2062; (c) Z. Niu, S. Lin, Z. Dong, H.
Sun, F. Liang and J. Zhang, Org. Biomol. Chem., 2013, 11
,
2460–2465; (d) N. Chandna, N. Chandak, P. Kumar, J. K.
Kapoor and P. K. Sharma, Green Chem., 2013, 15, 2294–
2301.
For C-H amination, see: (a) J.-L. Liang, S.-X. Yuan, J.-S. Huang,
W.-Y. Yu and C.-M. Che, Angew. Chem. Int. Ed., 2002, 41
Scheme 7. Control experiment..
,
3465−3468; (b) K. W. Fiori and J. D. Bois, J. Am. Chem. Soc.,
2007, 129, 562−568; (c) C. Liang, F. Collet, F. Robert-Peillard,
P. Muller, R. H. Dodd and P. Dauban, J. Am. Chem. Soc., 2008,
130, 343−350; (d) J. A. Jordan-Hore, C. C. C. .Johansson, M.
Gulias, E. M. Beck and M. J. Gaunt, J. Am. Chem. Soc., 2008,
130, 16184−16186; (e) Y. M. Badiei, A. Dinescu, X. Dai, R. M.
Palomino, F. W. Heinemann, T. R. Cundari and T. H. Warren,
Angew. Chem. Int. Ed., 2008, 47, 9961–9964; (f) M. J. B.
Aguila, Y. M. Badiei and T. H. Warren, J. Am. Chem. Soc.,
2013, 135, 9399−9406; (g) E. S. Jang, C. L. McMullin, M. Käß,
K. Meyer, T. R. Cundari and T. H. Warren, J. Am. Chem. Soc.,
2014, 136, 10930−10940.
Conclusions
In summary, we have discovered a transition-metal-free method
for directly constructing new C=N bonds through oxidative DTCC
reactions, which provide a novel strategy to generate sulfonyl
amidines with N,N-dimethyl aniline and sulfonamide. And this
effecitve process use commercially available and abundant
substrates as starting materials and was catalyed by inexpensive
NaI. It could be expect that this unanticipated finding would have a
broader role on dehydrogenative cross-coupling by removing four
hydrogen atoms in one-pot. The further application of our method
for biologically active molecules synthesis is underway in our
laboratory.
8
9
(a) C.-L. Sun, H. Li, D.-G. Yu, M. Yu, X. Zhou, X.-Y. Lu, K.
Huang, S.-F. Zheng, B.-J. Li and Z.-J. Shi, Nat. Chem., 2010, 2,
1044-1049; (b) W. Liu, H. Cao, H. Zhang, H. Zhang, K. H.
Chung, C. He, H. Wang, F. Y. Kwong and A. Lei, J. Am. Chem.
Soc., 2010, 132, 16737-16740; (c) G. Deng, K. Ueda, S.
Yanagisawa, K. Itami and C. Li, Chem. Eur. J., 2009, 15, 333-
337; (d) S. Yanagisawa, K. Ueda, T. Taniguchi and K. Itami,
Org. Lett., 2008, 10, 4673-4676.
Acknowledgements
See Supporting Information for details.
10 (a) X. Ling, Y. Xiong, R. Huang, X. Zhang, S. Zhang and C.
Chen, J. Org. Chem., 2013, 78, 5218−5226; (b) S. Murata, M.
Miura and M. Nomura, J. Chem. Soc., Chem. Commun., 1989,
116-118; (c) S. Murata, M. Miura and M. Nomura, J. Org.
Chem., 1989, 54, 4700-4702; (d) X. Chen, T. Chen, Y. Xiang, Y.
Zhou, D. Han, L.-B. Han and S.-F. Yi, Tetrahedron Lett., 2014,
4572-4575; (e) T. Sakakibara, S. Karasumaru and I. Kawano, J.
Am. Chem. Soc., 1985, 107, 6417-6419; (f) L.-T. Li, J. Huang,
H.-Y. Li, L.-J. Wen, P. Wang and B. Wang, Chem. Commun.,
2012, 48, 5187-5189; (g) C. D. Prasad, S. J. Balkrishna, A.
Kumar, B. S. Bhakuni, K. Shrimali, S. Biswas and S. Kumar, J.
Org. Chem., 2013, 78, 1434-1443.
We gratefully acknowledge the grants from the Research Grant
under the SA/China Agreement on Cooperation in Science and
Technology, the Scientific Research Foundation for the Returned
Overseas Chinese Scholars, State Education Ministry; the Priority
Academic Program Development of Jiangsu Higher Education
Institutions; and the Key Laboratory of Organic Synthesis of Jiangsu
Province.
Notes and references
11 (a) Q. Xia, X. Liu, Y. Zhang, C. Chen and W. Chen, Org. Lett.,
2013, 15, 3326−3329; (b) Y. Zhu, H. Yan, L. Lu, D. Liu, G. Rong
and J. Mao, J. Org. Chem., 2013, 78, 9898−9905; (c) Y. Zhang,
J. Feng and C.-J. Li, J. Am. Chem. Soc., 2008, 130, 2900-2901;
1
(a) C.-J. Li, Acc. Chem. Res., 2009, 42, 335−344; (b) C. Liu, H.
Zhang, W. Shi and A. Lei, Chem. Rev., 2011, 111, 1780−1824;
(c) C. S. Yeung and V. M. Dong, Chem. Rev., 2011, 111
,
1215−1292; (d) C.-L. Sun, B.-J. Li and Z.-J. Shi, Chem. Rev.,
2011, 111, 1293−1314; (e) C. Zhang, C. Tang and N. Jiao,
Chem. Soc. Rev., 2012, 41, 3464–3484; (f) S. A. Girard, T.
Knauber and C.-J. Li, Angew. Chem. Int. Ed., 2013, 52, 2-29; (g)
(d) Z. Xu, C. Yan and Z.-Q. Liu, Org. Lett., 2014, 16
5670−5673.
12 Y. Zhang, H. Fu, Y. Jiang and Y. Zhao, Org. Lett., 2007,
,
9
,
3813−3816.
13 (a) W. Wei, C. Zhang, Y. Xu and X. Wan, Chem. Commun.,
2011, 47, 10827–10829; (b) L.-T. Li, H.-Y. Li, L.-J. Xing, L.-J.
J. Zhou, C. Jin, X. Li and W. Su, RSC Adv., 2015,
7236; (h) B. Dadpou and D. Nematollahi, RSC Adv., 2014,
50365-50368; (i) A. Sagar, S. Vidyacharan and D. S. Sharada,
RSC Adv , 2014, , 37047-37050; (j) C. Zheng and S. You, RSC
Adv., 2014, , 6173-6214.
5, 7232-
4,
Wen, P. Wang and B. Wang, Org. Biomol. Chem., 2012, 10
,
.
4
9519–9522; (c) E. Shi, Y. Shao, S. Chen, H. Hu, Z. Liu, J. Zhang
and X. Wan, Org. Lett., 2012, 14, 3384-3387; (d) W.-P. Mai,
H.-H. Wang, Z.-C. Li, J.-W. Yuan, Y.-M. Xiao, L.-R. Yang, P.
Mao and L.-B. Qu, Chem. Commun., 2012, 48, 10117–10119;
(e) S. Tang, Y. Wu, W. Liao, R. Bai, C. Liu and A. Lei, Chem.
Commun., 2014, 50, 4496−4499; (f) D. Zhao, T. Wang, Q.
Shen and J.-X. Li, Chem. Commun., 2014, 50, 4302−4304.
14 (a) Y. Yan, Y. Zhang, C. Feng,; Z. Zha and Z. Wang, Angew.
Chem. Int. Ed., 2012, 51, 8077−8081; (b) Y. Yan, Y. Zhang, Z.
Zha and Z. Wang, Org. Lett., 2013, 15, 2274−2277; (c) D.
4
2
(a) C. Zhang and N. Jiao, Angew. Chem. Int. Ed., 2010, 49
6174–6177; (b) Y. Zhu and Y. Shi, Org. Lett., 2013, 15
1942−1945.
,
,
3
4
G. Li, S. Qian, C. Wang and J. You, Angew. Chem. Int. Ed.,
2013, 52, 7837–7840.
(a) X. Xu, X. Li, L. Ma, N. Ye and B. Weng, J. Am. Chem. Soc.,
2008, 130, 14048–14049; (b) X. Xu, Z. Ge, D. Cheng, C. Lu, Q.
Zhang, N. Yao and X. Li, Org. Lett., 2010, 12, 897−899.
5
(a) I. Bea, H. Han and S. Chang, J. Am. Chem. Soc., 2005, 127,
2038−2039; (b) S. Chang, M. Lee, D. Y. Jung, E. J. Yoo, S. H.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
RSC Advances
Page 6 of 6
View Article Online
DOI: 10.1039/C5RA06773A
Journal Name
COMMUNICATION
Zhao, T. Wang, Q. Shen and J.-X. Li, Chem. Commun., 2014,
50, 4302−4304.
Fares and M. Klussmann, J. Am. Chem. Soc., 2011, 133,
8106−8109; (j) M. Ghobrial, M. Schnurch and M. D.
15 (a) M. O. Ratnikov and M. P. Doyle, J. Am. Chem. Soc., 2013,
135, 1549–1557; (b) S.-I. Murahashi, N. Komiya and H. Terai,
Angew. Chem. Int. Ed., 2005, 44, 6931 –6933; (c) S.-I.
Mihovilovic, J. Org. Chem., 2011, 76, 8781−8793; (k) E. Boess,
,
C. Schmitz and M. Klussmann, J. Am. Chem. Soc., 2012, 134
5317−5325.
Murahashi, N. Komiya, H. Terai and T. Nakae, J. Am. Chem. 21 (a) W. Han and A. R. Ofial, Chem. Commun., 2009, 5024–
Soc., 2003, 125, 15312-15313; (d) S.-I. Murahashi, T. Nakae,
H. Terai and N. Komiya,J. Am. Chem. Soc., 2008, 130, 11005–
11012.
5026; (b) H. Li, Z. He, X. Guo, W. Li, X. Zhao and Z. Li, Org.
Lett., 2009, 11, 4176−4179; (c) C. M. R. Volla and P. Vogel,
Org. Lett., 2009, 11, 1701−1704; (d) P. Liu, C.-Y. Zhou, S.
Xiang and C.-M. Che, Chem. Commun., 2010, 46, 2739–2741;
(e) G. Kumaraswamy, A. N. Murthy and A. Pitchaiah, J. Org.
Chem., 2010, 75, 3916–3919; (f) Y. Li, F. Jia and Z. Li, Chem.
Eur. J., 2013, 19, 82–86; (g) Y. Li, L. Ma, F. Jia and Z. Li, J. Org.
Chem., 2013, 78, 5638−5646.
16 (a) V. Petrov, V. Petrova, G. V. Girichev, H. Oberhammer, N. I.
Giricheva and S. Ivanov, J. Org. Chem., 2006, 71, 2952-2956;
(b) G. Pelletier and D. A. Powell, Org. Lett., 2006,
6031−6034; (c) X.-Q. Yu, J.-S. Huang, X.-G. Zhou and C.-M.
Che, Org. Lett., 2000, , 2233−2236; (d) S.-M. Au, J.-S. Huang,
8,
2
C.-M. Che and W.-Y. Yu, J. Org. Chem., 2000, 65, 7858-7864; 22 K. Alagiri and K. R. Prabhu, Org. Biomol. Chem., 2012, 10,
835−842.
(e) A. Mielgo and C. Palomo, Chem. Asian J., 2008,
922−948.
3
,
23 Y. Zhang, H. Peng, M. Zhang, Y. Cheng and C. Zhu, Chem.
Commun., 2011, 47, 2354−2356.
17 (a) S.-I. Murahashi, N. Komiya, H. Terai and T. Nakae, J. Am.
Chem. Soc.
Komiya and H. Terai, Angew. Chem. Int. Ed., 2005, 44, 6931–
6933; (c) S.-I. Murahashi, T. Nakae, H. Terai and N. Komiya, J. 25 (a) S. Singhal, S. L. Jain and B. Sain, Chem. Commun., 2009,
,
2003, 125, 15312−15313; (b) S.-I. Murahashi, N. 24 A. Lin,; H. Peng, A. Abdukader and C. Zhu, Eur. J. Org. Chem.,
2013, 7286–7290.
Am. Chem. Soc., 2008, 130, 11005−11012; (d) A. G. Condie, J.
C. Gonzalez-Gomez and C. R. J. Stephenson, J. Am. Chem.
Soc., 2010, 132, 1464-1465; (e) M.-Z. Wang, C.-Y. Zhou, M.-K.
Wong and C.-M. Che, Chem. Eur. J., 2010, 16, 5723−5725; (f)
2371-2372; (b) A. Sud, D. Sureshkumarz and M. Klussmann,
Chem. Commun., 2009, 3169–3171; (c) K. Alagiri, G. S. R.
Kumara and K. R. Prabhu, Chem. Commun., 2011, 47
11787−11789.
,
M. Rueping, C. Vila, R. M. Koenigs, K. Poscharny and D. C. 26 (a) J. Dhineshkumar, M. Lamani, K. Alagiri and K. R. Prabhu,
Fabry, Chem. Commun., 2011, 47, 2360−2362.
18 A. J. Catino, J. M. Nichols, B. J. Nettles and M. P. Doyle, J. Am.
Chem. Soc., 2006, 128, 5648−5649.
Org. Lett., 2013, 15, 1092–1095; (b) C. Zhang, C. Liu, Y. Shao,
X. Bao and X. Wan, Chem. Eur. J., 2013, 19, 17917−17925; (c)
A. Tanoue, W.-J. Yoo and S. Kobayashi, Org. Lett., 2014, 16
,
19 R. Magnus, S. Zhu and R. M. Koenigs, Chem. Commun., 2011,
47, 12709-12711.
2346−2349; (d) H. Ueda, K. Yoshida and H. Tokuyama, Org.
Lett., 2014, 16, 4194−4197; (e) Z.-Q. Lao, W.-H. Zhong, Q.-H.
20 (a) Z. Li and C.-J. Li, J. Am. Chem. Soc., 2004, 126
,
Lou, Z.-J. Li and X.-B. Meng, Org. Biomol. Chem., 2012, 10
7869–7871; (f) A. Kumar, M. K. Gupta, M. Kumar and D.
Saxena, RSC Adv., 2013, , 1673-1678; (g) E. Manoni, A.
Gualandi, L. Mengozzi, M. Bandini and P. G. Cozzi, RSC Adv.,
2015, , 10546-10550; (h) H.-M. Huang, J.-R. Gao, Q. Ye, W.-
B. Yu, W.-J. Sheng and Y.-J. Li, RSC Adv., 2014, , 15526-
15533; (i) D. B. Ramachary, R. Sakthidevi and P. S. Reddy, RSC
Adv., 2013, , 13497–13506.
,
11810−11811; (b) Z. Li, D. S. Bohle and C.-J. Li, Proc. Natl.
Acad. Sci. U. S. A., 2006, 103, 8928−8933; (c) L. Zhao and C.-J.
Li, Angew. Chem. Int. Ed., 2008, 47, 7075–7078; (d) Y. Shen,
M. Li, S. Wang, T. Zhan, Z. Tan and C.-C. Guo, Chem.
Commun., 2009, 953–955; (e) X. Xu and X. Li, Org. Lett.,
2009, 11, 1027−1029; (f) L. Zhao, B. Oliver and C.-J. Li, Proc.
Natl. Acad. Sci. U. S. A., 2009, 106, 4106−4611; (g) J. Xie and
3
5
4
3
Z.-Z. Huang, Angew. Chem. Int. Ed., 2010, 49, 10181−10185; 27 (a) L. Zhao, O. Baslea and C.-J. Li, Proc. Natl. Acad. Sci. U. S. A.,
2009, 106, 4106–4111; (b) L. Zhao and C.-J. Li, Angew. Chem.
Int. Ed., 2008, 47, 7075–7078.
(h) F. Yang, J. Li, J. Xie and Z.-Z. Huang, Org. Lett., 2010, 12,
5214−5217; (i) E. Boess, D. Sureshkumar, A. Sud, C. Wirtz, C.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins