Ligand-promoted, copper nanoparticles catalyzed one-pot synthesis of substituted benzoxazoles from 2-bromoanilines and acyl chlorides

Article abstract of DOI:10.1016/j.tetlet.2015.10.078

A facile, highly efficient, and practical one-pot synthetic strategy for benzoxazoles was developed by using copper nanoparticles as a catalyst with o-bromoanilines and acyl chlorides as starting materials. With the promotion of 1,10-phenanthroline ligand, the copper nanoparticles catalyst showed highly catalytic activity under mild conditions. This methodology is tolerant of a wide variety of functional groups and gives good to excellent yields in most examples. Furthermore, the solid catalyst could be recovered and reused conveniently several times with satisfactory yields.

Full text of DOI:10.1016/j.tetlet.2015.10.078

Tetrahedron Letters xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Ligand-promoted, copper nanoparticles catalyzed one-pot synthesis
of substituted benzoxazoles from 2-bromoanilines and acyl chlorides
⇑
Yong Wang, Chaolong Wu, Shoujie Nie, Dingjian Xu, Min Yu, Xiaoquan Yao
Department of Applied Chemistry, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
A facile, highly efficient, and practical one-pot synthetic strategy for benzoxazoles was developed by
using copper nanoparticles as a catalyst with o-bromoanilines and acyl chlorides as starting materials.
With the promotion of 1,10-phenanthroline ligand, the copper nanoparticles catalyst showed highly cat-
alytic activity under mild conditions. This methodology is tolerant of a wide variety of functional groups
and gives good to excellent yields in most examples. Furthermore, the solid catalyst could be recovered
and reused conveniently several times with satisfactory yields.
Received 4 September 2015
Revised 22 October 2015
Accepted 25 October 2015
Available online xxxx
Keywords:
Benzoxazoles
Ó 2015 Elsevier Ltd. All rights reserved.
Copper nanoparticles
Ligand-promoted
One-pot synthesis
As a kind of classic five-membered heterocyclic rings, benzoxa-
zoles have been extensively studied.1 Researches show that it is an
important structure unit in many compounds, such as natural
products,2 pharmaceutical and agrochemical compounds,3,4 fluo-
rescent materials,5 and other functional materials.6,7 Among the
various synthetic methodologies reported,8,9 the strategy with
2-haloanilides as starting material provides an effective and prac-
tical approach to the synthesis of benzoxazoles.9 In this methodol-
ogy, 2-haloanilides, which are usually prepared in advance from
acyl chlorides and o-haloanilines, followed a catalytic intramolec-
ular O-arylation to give the target molecule. Till now, many cata-
lysts have been reported, in which copper catalysts attracted the
most attention.9
Although these reactions provide efficient approaches to ben-
zoxazoles, harsh reaction conditions were usually required in most
examples (such as high temperature, long reaction times, low
yield, much excess strong bases, and so on). Furthermore, in most
of reported examples, the o-haloanilides have to be prepared pre-
viously, and there are only a few examples on the one-pot synthe-
sis of benzoxazoles from 2-haloaniline and acid chlorides. In 2008,
Batey and his co-workers reported an excellent example on the
one-pot synthesis of benzoxazoles with 2-haloanilines and acid
chlorides as starting materials. However, it was worthy to note that
extremely high temperature is necessary for good yields in this
example, and the promotion of microwave was required.9e
Therefore, a more effective, mild, and environmentally friendly
process is needed.
Recently, the synthesis and application of metal nanoparticles
have received considerable attention in view of their unique prop-
erties compared to the bulk metals. Metal nanoparticles have a
characteristic high surface area that translates into more active
sites per unit area, and can maximize the reaction rates and mini-
mize consumption of the catalyst.10 Copper nanoparticles (Cu NPs),
being cheap, with unusual properties and potential applications
are particular attractive and there are many excellent examples
reported on their utilization in organic reaction.11 In 2009, Pun-
niyamurthy’s group also reported an excellent example on using
nano CuO as an effective catalyst for the intramolecular coupling
of o-haloanilides,9f and a magnetic copper ferrite nanoparticles
catalyst was also reported for the reaction very recently.9i
However, in both of the examples, long reaction time at high
temperature was required, and o-haloanilides needed to be
prepared in advance.
In comparison with most of the examples using surfactant-free
nanoparticles as catalysts, there are few examples reported about
the ligand effect on coinage metal nanoparticle-catalyzed reac-
tions. Recently, several ligand-promoted or ligand & support-
promoted, coinage nanoparticle-catalyzed reactions were reported
by our groups and others,12 in which the utilization of ligands
proved to be the key role to the reaction. Herein, we hope to utilize
this strategy to develop a highly efficient, ligand-promoted, Cu
NPs-catalyzed one-pot Domino reaction to prepare 2-substituted
benzoxazoles from o-bromoanilines and acyl chlorides. In the pres-
ence of 1,10-phenanthroline as ligand, excellent yields were
⇑
Corresponding author. Tel.: +86 25 52112902; fax: +86 25 52112626.
E-mail address: yaoxq@nuaa.edu.cn (X. Yao).
http://dx.doi.org/10.1016/j.tetlet.2015.10.078
0040-4039/Ó 2015 Elsevier Ltd. All rights reserved.
Please cite this article in press as: Wang, Y.; et al. Tetrahedron Lett. (2015), http://dx.doi.org/10.1016/j.tetlet.2015.10.078

2
Y. Wang et al. / Tetrahedron Letters xxx (2015) xxx–xxx
Scheme 2. Ligand-promoted, Cu NPs-catalyzed one-pot reaction of 2-chloroaniline
(5) and benzoyl chloride (2a).
Scheme 1. Ligand-promoted, Cu NPs-catalyzed one-pot synthesis of substituted
benzoxazoles.
obtained (entries 11–16).13 In addition, the desired product was
not detected when the reaction was carried out in toluene, DCM,
DCE, or THF solution (entries 17–20). Using DMF or water instead
also inhibited the catalytic activity of Cu NPs (entries 21 and 22).
On the other hand, in the absence of Cu NPs catalyst, a blanket
reaction was carried out and only stoichiometric o-bromoanilide
3a was recovered (entry 23).
Following the standard reaction conditions in entry 2,
Table 1 and 2-chloroaniline was also detected (Scheme 2).
Obviously, current copper catalyst showed less catalytic activity
to 2-chloroaniline.
With the optimized reaction conditions (10 mol % of Cu NPs,
10 mol % of 1,10-phen and 2 equiv of K2CO3 in 1.5 mL of MeCN at
90 °C under nitrogen), substrate scope was investigated by reacting
various aromatic acyl chlorides and anilines. Typical results are
listed in Table 2.
achieved in most cases under mild conditions in several hours
(Scheme 1).
The reaction of o-bromoaniline (1a) and benzoyl chloride (2a)
was selected as the prototype to start our investigation for the
optimized reaction conditions, and the data are summarized in
Table 1. When 1a (0.2 mmol) and 1.2 equiv of 2a were treated with
10 mol % of Cu NPs, 10 mol % of 1,10-phen and 2 equiv of K2CO3 in
1.5 mL of MeCN at 80 °C under nitrogen for 4 h, 3a and 4a were
obtained in 64% and 36% yields, respectively (Table 1, entry 1).
When the reaction was carried out at 90 °C, significantly shortened
reaction time was observed, and benzoxazole 4a was obtained in a
>99% of yield (Table 1, entry 2). Other bases, such as Cs2CO3, K3PO4,
and Na2CO3, were screened under the same condition, only
lower yields and worse selectivities were observed (entries 3–5
vs entry 2). A base-free condition was also detected, and only
2-bromoanilide 3a was isolated with
a stoichiometric yield
(entry 6). Changing the ligand from 1,10-phen to bipyridine,
triphenylphosphine all led to poor yields and selectivities (entries
7–8). Ligand-free condition was then tested, and only 13% of yield
was observed (entry 9). The Cu Nps-catalyzed reaction was also
carried out in air, and only 79% of 4a was obtained (entry 10).
Copper salts, such as CuCl, CuI, CuCl2, CuBr2, Cu(OAc)2, and Cu
(NO3)2, were also examined, and no satisfactory results were
It can be seen from Table 2 that most of the substrates gave the
corresponding products in excellent yields, except the examples
with 2-chlorobenzoyl chloride (2f) as starting material (Table 2,
entries 1–5, 7–11 and 13–17 vs entries 6, 12 and 18). The
substituents on o-bromoanilines, no matter whether it is elec-
tron-donating or electron-withdrawing, showed less effect on the
reaction. On the contrary, the substituent on aromatic acyl chlo-
Table 1
Optimization of the catalytic reaction conditionsa
Entry
Catalyst
Ligand
Base
Solvent
Temp (°C)
Time (h)
Yieldb (3a) (%)
Yieldb (4a) (%)
1
2
3
4
5
6
7
8
9
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
CuCl
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
2,20-bipy
PPh3
K2CO3
K2CO3
Cs2CO3
K3PO4
Na2CO3
Free
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
MeCN
Toluene
DCE
80
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
90
40
90
90
90
90
90
4
1
1
1
2
1
2
2
2
2
1
4
1
1
1
1
64
0
18
35
84
100
24
80
87
15
55
46
24
18
46
82
36
>99
72
65
16
N. D.
76
20
13
79
45
53
76
72
54
18
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
K2CO3
Free
10c
11
12
13
14
15
16
17
18
19
20
21
22
23
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phen
1,10-Phe
1,10-Phen
1,10-Phen
1,10-Phen
CuI
CuCl2
CuBr2
Cu(OAc)2
Cu(NO3)2
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
Cu-NPs
Free
1.5
2
>99
>99
100
100
92
Trace
Trace
N. D.
N. D.
8
DCM
THF
DMF
H2O
1.5
1.5
1.5
1.5
1
54
100
46
N. D.
MeCN
a
b
c
Reaction conditions: 1a (0.2 mmol), 2a (1.2 equiv), catalyst (10 mol %), ligand (10 mol %), base (2 equiv), solvent (1.5 mL), stirred under N2.
Isolated yields.
The reaction was carried out in air.
Please cite this article in press as: Wang, Y.; et al. Tetrahedron Lett. (2015), http://dx.doi.org/10.1016/j.tetlet.2015.10.078

Y. Wang et al. / Tetrahedron Letters xxx (2015) xxx–xxx
3
Table 2
Copper nanoparticles catalyzed one-pot reaction of o-bromoanilines and acyl chloridesa
Entry
1
R1
R2
Product
Time (h)
1
Yieldb (%)
>99
H (1a)
H (2a)
2
3
4
H
H
H
4-CH3 (2b)
4-OMe (2c)
4-Cl (2d)
1.5
2
99
98
1.5
>99
5
6
H
H
2-OMe (2e)
2-Cl (2f)
3
99
58
10
7
8
CH3 (1b)
CH3
H
1.5
2
>99
98
4-CH3
4-OMe
4-Cl
9
CH3
2
>99
96
10
CH3
2.5
11
12
CH3
CH3
2-OMe
2-Cl
2
96
54
10
13
14
15
16
F (1c)
H
2
96
98
98
93
F
F
F
4-CH3
4-OMe
4-Cl
2
2
3.5
17
F
2-OMe
2.5
97
(continued on next page)
Please cite this article in press as: Wang, Y.; et al. Tetrahedron Lett. (2015), http://dx.doi.org/10.1016/j.tetlet.2015.10.078

4
Y. Wang et al. / Tetrahedron Letters xxx (2015) xxx–xxx
Table 2 (continued)
Entry
R1
F
R2
Product
Time (h)
10
Yieldb (%)
49
18
2-Cl
a
Reaction conditions: o-bromoanilines (0.2 mmol), acyl chlorides (1.2 equiv), copper nanoparticles (10 mol %), 1,10-phen (10 mol %), K2CO3 (2 equiv), MeCN (1.5 mL),
stirred at 90 °C under N2.
b
Isolated yields.
Table 3
Copper nanoparticles catalyzed one-pot reaction of o-bromoanilines and acyl
chloridesa
Scheme 3. Ligand-promoted, Cu NPs-catalyzed one-pot reaction of 2-bromo-5-
methoxyaniline (6) and acyl chlorides.
Entry R1
R2
Product
Time
(h)
Yieldb
(%)
ride, especially on ortho-position, showed significant influence on
the reaction (entries 5 vs 6, 11 vs 12, and 17 vs 18). It is also worthy
to note that the Cu NPs catalyst showed excellent catalytic activi-
ties in most of examples under the mild conditions, in which
most of reactions finished in ca. 1–3 h except the reactions with
2-chlorobenzoyl chloride as substrate (entries 6, 12 and 18).14
Some aliphatic, vinylic, and heterocyclic acyl chlorides were
also screened to further investigate the scope of the reaction and
the data are summarized in Table 3. For most substrates, the
one-pot reaction finished rapidly and resulted in excellent yields.
Cinnamoyl chlorides treated with 1a, 1b, and 1c gave the corre-
sponding product in 99%, 99%, and 98% of yields, respectively
(Table 3, entries 1, 5 and 9). Interestingly, the long chain aliphatic
acyl chloride (2i) gave 97–99% yields with substituted o-bromoani-
lines in 2 h (entries 3, 7 and 11), while only mediate yields were
observed with acetyl chloride (2h) as substrate even after much
longer reaction time (entries 2, 6 and 10). Furoic acid chloride
was also tested and showed excellent reactivity in the catalytic
one-pot reaction (Table 3, entries 4, 8, and 12).
A methoxy-substituted aniline, 2-bromo-5-methoxyaniline (6)
was also utilized in the one-pot reaction. It can be seen from
Scheme 3 that the electron-rich substrate showed lower reactivi-
ties than other anilines we once used, and the reaction with ben-
zoyl chloride gave the best yield at 100 °C after 3 h.15
One of the advantages of heterogeneous catalysts is their easy
separation from the reaction mixture. The Cu NPs catalyst could
be separated and recovered conveniently by centrifugation from
the reaction mixture, and then, fresh substrates and base were
added to set up a new reaction. Following this procedure, the cat-
alyst was recycled effectively, and the results are summarized in
Table 4. We found that the copper nanoparticles catalyst could
be reused 2–3 times without appreciable loss in yields (Table 4).
The slightly decreased catalytic activity might be due to the con-
glomeration and/or the loss of the nanoparticle catalyst.16
H
1
PhCH@CH
(2g)
3
99
69c
99c
99
(1a)
2
3
4
5
H
CH3 (2h)
5
n-C11H23
(2i)
H
H
1
2-Furyl
(2j)
0.5
2
CH3
(1b)
PhCH@CH
CH3
99
6
7
CH3
CH3
CH3
6
63c
98c
93
n-C11H23
2-Furyl
2
8
0.75
4
9
F (1c) PhCH@CH
98
10
11
12
F
F
F
CH3
8
54c
97c
89
n-C11H23
2-Furyl
1.5
1
At last, as a practical one-pot approach to the synthesis of ben-
zoxazoles, a gram-scale reaction of 1a and 2a was also examined.
6 mmol of 1a reacted with 7.2 mmol of 2a in 15 mL of MeCN,
and 93% of 4a was achieved (Scheme 4).
In conclusion, a facile, efficient, and practical one-pot synthetic
strategy for benzoxazoles was developed by using copper nanopar-
ticles as catalyst with o-bromoanilines and acyl chlorides as
a
Reaction conditions: o-bromoanilines (0.2 mmol), acyl chlorides (1.2 equiv),
copper nanoparticles (10 mol %), 1,10-phen (10 mol %), K2CO3 (2 equiv), MeCN
(1.5 mL), stirred at 90 °C under N2.
b
Isolated yields.
At 100 °C.
c
Please cite this article in press as: Wang, Y.; et al. Tetrahedron Lett. (2015), http://dx.doi.org/10.1016/j.tetlet.2015.10.078

Y. Wang et al. / Tetrahedron Letters xxx (2015) xxx–xxx
5
Table 4
2758–2761; (e) Pan, J.; Liu, G. Y.; Cheng, J.; Chen, X. J.; Ju, X. L. Eur. J. Med. Chem.
2010, 45, 967–972; (f) Bu, X. Y.; Chen, J. J.; Deady, L. W.; Denny, W. A.
Tetrahedron 2002, 175–181; (g) Grobler, J. A.; Dornadula, G.; Rice, M. R.;
Simcoe, A. L.; Hazuda, D. J.; Miller, M. D. J. Biol. Chem. 2007, 282, 8005–8010.
4. (a) Rasmussen, K.; Hsu, M. A.; Yang, Y. L. Neuropsychopharmacology 2007, 32,
786–792; (b) Yildiz-Oren, I.; Yalcin, I.; Aki-Sener, E.; Ucarturk, N. Eur. J. Med.
Chem. 2004, 39, 291–298; (c) Van Zandt, M. C.; Jones, M. L.; Gunn, D. E.; Geraci,
L. S.; Jones, J. H.; Sawicki, D. R.; Sredy, J.; Jacot, J. L.; DiCioccio, A. T.; Petrova, T.;
Mitschler, A.; Podjarny, A. D. J. Med. Chem. 2005, 48, 3141–3152; (d) Sweis, R. F.;
Hunt, J. A.; Kallashi, F.; Hammonda, M. L.; Chen, Y.; Eveland, S. S.; Guo, Q.;
Hyland, S. A.; Milot, D. P.; Cumiskey, A. M.; Latham, M.; Rosa, R.; Peterson, L.;
Sparrow, C. P.; Wright, S. D.; Anderson, M. S.; Sinclair, P. J. Bioorg. Med. Chem.
Lett. 2011, 21, 1890–1895; (e) Easmon, J.; Pürstinger, G.; Thies, K. S.; Heinisch,
G.; Hofmann, J. J. Med. Chem. 2006, 49, 6343–6350.
5. (a) Chen, C. J.; Wu, Y. C.; Sheu, H. S.; Lee, G. H.; Lai, C. K. Tetrahedron 2011, 67,
114–124; (b) Taki, M.; Wolford, J. L.; O’Halloran, T. V. J. Am. Chem. Soc. 2004,
126, 712–713; (c) Cellier, M.; Fabrega, O. J.; Fazackerley, E.; James, A. L.; Orenga,
S. Bioorg. Med. Chem. 2011, 19, 903–2910; (d) Tanaka, K.; Kumagai, T.; Aoki, H.;
Deguchi, M.; Iwata, S. J. Org. Chem. 2001, 66, 7328–7333.
6. (a) Hodgkin, J. H.; Liu, M. S.; Dao, B. N.; Maradel, J.; Hill, A. J. Eur. Polym. J. 2011,
47, 394–400; (b) Liu, J. G.; Nakamura, Y.; Ogura, T.; Shibasaki, Y.; Ando, S.;
Ueda, M. Chem. Mater. 2008, 20, 273–281; (c) Ogoshi, T.; Miyake, J.; Chujo, Y.
Macromolecules 2005, 38, 4425–4431; (d) Bourbigot, S.; Flambard, X. Fire Mater.
2002, 26, 155–168; (e) Martínez, K. T.; Villar-Rodil, S.; Paredes, J. I.; Alonso, A.
M.; Tascón, J. M. D. Chem. Mater. 2003, 15, 4052–4059; (f) Wu, C. C.; Tsay, P. Y.;
Cheng, H. Y.; Baib, S. J. J. Appl. Phys. 2004, 95, 15.
Recycling of the copper nanoparticle catalysta
b
Run
Reaction time (h)
Yield (%)
1
2
3
4
1
2
6
>99
97
93
20
74
a
Reaction conditions: o-bromoanilines (1 mmol), acyl chlorides (1.2 equiv), Cu
NPs (10 mol %), 1,10-phen (10 mol %), K2CO3 (2 equiv), MeCN (5 mL), stirred at 90 °C
under N2.
b
Isolated yields.
7. (a) Liao, C. C.; Wang, C. S.; Sheu, H. S.; Lai, C. K. Tetrahedron 2008, 64, 7977–
7985; (b) Wu, I. T.; Chaing, P. Y.; Chang, W. J.; Sheu, H. S.; Lee, G. H.; Lai, C. K.
Tetrahedron 2011, 67, 358–7369.
8. Some selected recent examples: (a) Wang, Y.; Sarris, K.; Sauer, D. R.; Djuric, S.
W. Tetrahedron Lett. 2006, 47, 4823–4826; (b) Yang, Y. H.; Shi, M. Tetrahedron
2006, 62, 2420–2427; (c) Downer-Riley, N. K.; Jackson, Y. A. Tetrahedron 2007,
63, 10276–10281; (d) Seijas, J. A.; Vázquez-Tato, M. P.; Carballido-Reboredo, M.
R.; Crecente-Campo, J.; Romar-López, L. Synlett 2007, 313–316; (e) Lim, H. J.;
Myung, D.; Lee, I. Y. C.; Jung, M. H. J. Comb. Chem. 2008, 10, 501–503; (f) Ueda,
S.; Nagasawa, H. Angew. Chem. Int. Ed. 2008, 47, 6411–6413; (g) Chen, W. H.;
Pang, Y. Tetrahedron Lett. 2009, 50, 6680–6683; (h) Li, K. L.; Du, Z. B.; Guo, C. C.;
Chen, Q. Y. J. Org. Chem. 2009, 74, 3286–3292; (i) Huang, J.; Chan, J.; Chen, Y.;
Borths, C. J.; Baucom, K. D.; Larsen, R. D.; Faul, M. M. J. Am. Chem. Soc. 2010, 132,
3674–3675; (j) Bose, D. S.; Idrees, M. Synthesis 2010, 398–402; (k) Boissarie, P.
J.; Hamilton, Z. E.; Lang, S.; Murphy, J. A.; Suckling, C. J. Org. Lett. 2011, 13,
6184–6187; (l) Guru, M. M.; Ali, M. A.; Punniyamurthy, T. J. Org. Chem. 2011, 76,
5295–5308; (m) Guru, M. M.; Ali, M. A.; Punniyamurthy, T. Org. Lett. 2011, 13,
1194–1197; (n) Chen, C.-Y.; Andreani, T.; Li, H. Org. Lett. 2011, 13, 6300–6303;
(o) Riadi, Y.; Mamouni, R.; Azzalou, R.; Haddad, M. E.; Routier, S.; Guillaumet,
G.; Lazar, S. Tetrahedron Lett. 2011, 52, 3492–3495; (p) Reddy, M. B. M.; Nizam,
A.; Pasha, M. A. Synth. Commun. 2011, 41, 1838–1842; (q) Bastug, G.; Eviolitte,
C.; Markó, I. E. Org. Lett. 2012, 14, 3502–3505; (r) Gorepatil, P. B.; Mane, Y. D.;
Ingle, V. S. Synlett 2013, 2241–2244; (s) Alla, S. K.; Sadhu, P.; Punniyamurthy, T.
J. Org. Chem. 2014, 79, 7502–7511; (t) Cao, X.; Cheng, X.; Bai, Y.; Liu, S.; Deng,
G.-J. Green Chem. 2014, 16, 4644–4648.
9. (a) Park, Y. T.; Jung, C. H.; Kim, K. W. J. Org. Chem. 1999, 64, 8546–8556; (b)
Evindar, G.; Batey, R. A. J. Org. Chem. 2006, 71, 1802–1808; (c) Barbero, N.;
Carril, M.; SanMartin, R.; Domínguez, E. Tetrahedron 2007, 63, 10425–10432;
(d) Bonnamour, J.; Bolm, C. Org. Lett. 2008, 10, 2665–2667; (e) Viirre, R. D.;
Evindar, G.; Batey, R. A. J. Org. Chem. 2008, 73, 3452–3459; (f) Saha, P.; Ramana,
T.; Purkait, N.; Ali, M. A.; Paul, R.; Punniyamurthy, T. J. Org. Chem. 2009, 74,
8719–8725; (g) Saha, P.; Ali, M. A.; Ghosh, P.; Punniyamurthy, T. Org. Biomol.
Chem. 2010, 8, 5692–5699; (h) Majumdar, K. C.; Ganai, S.; Nandi, R. K.; Ray, K.
Tetrahedron Lett. 2012, 53, 1553–1557; (i) Yang, D.; Zhu, A.; Wei, W.; Jiang, M.;
Zhang, N.; Ren, D.; You, J.; Wang, H. Synlett 2014, 729–735.
Scheme 4. Gram-scale reaction of 1a and 2a.
starting materials. With the promotion of 1,10-phen, Cu NPs
showed highly catalytic activity under mild conditions. This
methodology is tolerant of a wide variety of functional groups
and gives good to excellent yields for most examples. Furthermore,
the solid catalyst could be recovered and reused conveniently for
several times with satisfactory yields. The detailed mechanism,
the effect of particle size and particle support as well as the scope
of the reaction are currently under further investigations.
Acknowledgments
We are grateful to the financial support from National Natural
Science Foundation of China (21172107 to XY), A project funded
by the Priority Academic Program Development of Jiangsu higher
education institutions.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.tetlet.2015.10.
078.
10. For selected reviews, see: (a) Schauermann, S.; Nilius, N.; Shaikhutdinov, S.;
Freund, H.-J. Acc. Chem. Res. 2013, 46, 1673–1681; (b) Yasukawa, T.; Miyamura,
H.; Kobayashi, S. Chem. Soc. Rev. 2014, 43, 1450–1461; (c) Hervés, P.; Pérez-
Lorenzo, M.; Liz-Marzán, L. M.; Dzubiella, J.; Lu, Y.; Ballauff, M. Chem. Soc. Rev.
2012, 41, 5577–5587; (d) Dhakshinamoorthy, A.; Garcia, H. Chem. Soc. Rev.
2012, 41, 5262–5284.
11. For example, see: (a) Wang, F.; Shi, R.; Liu, Z.-Q.; Shang, P.-J.; Pang, X.; Shen, S.;
Feng, Z.; Li, C.; Shen, W. ACS Catal. 2013, 3, 890–894; (b) Marella, R. K.; Neeli, C.
K. P.; Kamaraju, S. R. R.; Burri, D. R. Catal. Sci. Technol. 2012, 2, 1833–1838; (c)
Ahammed, S.; Saha, A.; Ranu, B. C. J. Org. Chem. 2011, 76, 7235–7239; (d)
Alonso, F.; Moglie, Y.; Radivoy, G.; Yus, M. J. Org. Chem. 2013, 78, 5031–5037;
(e) Honraedt, A.; Callonnec, F. L.; Grognec, E. L.; Fernandez, V.; Felpin, F.-X. J.
Org. Chem. 2013, 78, 4604–4609; (f) Alonso, F.; Moglie, Y.; Radivoy, G.; Yus, M. J.
Org. Chem. 2011, 76, 8394–8405; (g) Deka, P.; Deka, R. C.; Bharali, P. New J.
Chem. 2014, 38, 1789–1793; (h) Kim, J. H.; Chung, Y. K. Chem. Commun. 2013,
49, 11101–11103.
References and notes
1. For example: (a) Chen, C. P.; Chen, Y. J. Tetrahedron Lett. 2004, 45, 113–115; (b)
Alagille, D.; Baldwina, R. M.; Tamagnan, G. D. Tetrahedron Lett. 2005, 46, 1349–
1351; (c) Yao, W.; Huang, D. J. Org. Lett. 2010, 12, 736–738; (d) Li, Y. M.; Xie, Y.
S.; Zhang, R.; Jin, K.; Wang, X. N.; Duan, C. Y. J. Org. Chem. 2011, 76, 5444–5449;
(e) Leng, Y. Y.; Yang, F.; Zhu, W. G.; Wu, Y. J.; Li, X. Org. Biomol. Chem. 2011, 9,
5288–5296; (f) Chen, W.; Wang, M.; Li, P. H.; Wang, L. Tetrahedron 2011, 67,
5913–5919.
2. (a) Davidson, J. P.; Corey, E. J. J. Am. Chem. Soc. 2003, 125, 13486–13489; (b)
Rodríguez, A. D.; Ramírez, C.; Rodríguez, I. I.; González, E. Org. Lett. 1999, 1,
527–530; (c) Kusumi, T.; Ooi, T.; Walchli, M. R.; Kakisawa, H. J. Am. Chem. Soc.
1988, 110, 2954–2958; (d) Don, M. J.; Shen, C. C.; Lin, Y. L.; Syu, W. J.; Ding, Y.
H.; Sun, C. M. J. Nat. Prod. 2005, 68, 1066–1070.
3. (a) Morningstar, M. L.; Roth, T.; Farnsworth, D. W.; Smith, M. K.; Watson, K.;
Buckheit, R. W.; Das, K.; Zhang, W. Y.; Arnold, E.; Julias, J. G.; Hughes, S. H.;
Michejda, C. J. J. Med. Chem. 2007, 50, 4003–4015; (b) Temiz-Arpacı, Ö.;
Özdemira, A.; Yalcın, I.; Yıldız, I.; Akı-Sener, E.; Altanlar, N. Arch. Pharm. Chem.
Life Sci. 2005, 338, 105–111; (c) Brown, R. N.; Cameron, R.; Chalmers, D. K.;
Hamilton, S.; Luttick, A.; Krippner, G. Y.; McConnell, D. B.; Nearn, R.;
Stanislawski, P. C.; Tucker, S. P.; Watson, K. G. Bioorg. Med. Chem. Lett. 2005,
15, 2051–2055; (d) Razavi, H.; Palaninathan, S. K.; Powers, E. T.; Wiseman, R. L.;
Purkey, H. E.; Mohamedmohaideen, N. N.; Deechongkit, S.; Chiang, K. P.;
Dendle, M. T. A.; Saccettini, J. C.; Kelly, W. Angew. Chem., Int. Ed. 2003, 42,
12.
A phosphine ligand-stablized Au(0) nanoparticle-catalyzed diboration: (a)
Ramirez, J.; Sanau, M.; Fernandez, E. Angew. Chem., Int. Ed. 2008, 47, 5194–
5197; An asymmetric example: (b) Gross, E.; Liu, J. H.; Alayoglu, S.; Marcus, M.
A.; Fakra, S. C.; Toste, F. D.; Somorjai, G. A. J. Am. Chem. Soc. 2013, 135, 3881–
3886; Recently, we also reported some examples about ligand-promoted, silver
or copper nanoparticals-catalyzed reactions, see: (c) Yu, M.; Lin, M.; Han, C.; Li,
Z.; Li, C.-J.; Yao, X. Tetrahedron Lett. 2010, 51, 6722–6725; (d) Han, C.; Yu, M.;
Sun, W.; Yao, X. Synlett 2011, 2363–2368; (e) Yu, M.; Wang, Y.; Sun, W.; Yao, X.
Adv. Synth. Catal. 2012, 354, 71–76; (f) Sun, W.; Wang, Y.; Wu, X.; Yao, X. Green
Please cite this article in press as: Wang, Y.; et al. Tetrahedron Lett. (2015), http://dx.doi.org/10.1016/j.tetlet.2015.10.078

6
Y. Wang et al. / Tetrahedron Letters xxx (2015) xxx–xxx
Chem. 2013, 15, 2356–2360; (g) Xu, S.; Zeng, S.; Wang, Y.; Yu, M.; Zhu, L.; Yao, regular heating condition, in which 12–24 h were usually required at higher
X. Chin. J. Org. Chem. 2015, 35, 827–834; (h) Lv, W.; Tian, J.; Deng, N.; Wang, Y.;
Zhu, X.; Yao, X. Tetrahedron Lett. 2015, 56, 1312–1315.
13. In Batey and his co-workers reported examples, with CuI & 1,10-phen as
catalyst, 10% of 3e and 80% of 4e were observed after 24 h reaction at 95 °C.
See: Ref. 9e.
temperature. See: ref. 9.
15. On the other hand, methyl 4-amino-3-bromobenzoate was also detected as an
electron-poor substrate reacting with 2a. However, only ca. 20% amide was
isolated and most of methyl 4-amino-3-bromobenzoate seemed decomposed.
16. Yan, W.; Wang, R.; Xu, Z.; Xu, J.; Lin, L.; Shen, Z.; Zhou, Y. J. Mol. Catal. A: Chem.
2006, 255, 81–85. A TEM image for the recovered Cu NPs was also provided in
SI. Serious conglomeration of nanoparticles can be observed.
14. To the best of our knowledge, this result might be one of the shortest reaction
time reported for the intramolecular O-arylation of o-haloanilides under
Please cite this article in press as: Wang, Y.; et al. Tetrahedron Lett. (2015), http://dx.doi.org/10.1016/j.tetlet.2015.10.078