2
520
G. Satish et al. / Tetrahedron Letters 53 (2012) 2518–2521
Table 1
Formation of 2-N-substituted benzothiazoles by reacting with 2-iodobenzamine with
carbon disulfide and N-nucleophiles
Entry Reactant = I
Reactant = II
Product
Yieldc
%)
(
NH2
N
N
70a
79a
1
N
H
S
I
NH2
N
S
2
N
H
N
I
NH2
I
N
N
69a
45a
75a
79a
3
4
5
6
N
H
F3C
S
F3C
Figure 2. TEM images of (a) native CuO nanoparticles, (b) CuO nanoparticles after
three cycles.
NH2
N
S
N
N
H
I
NH2
N
N
Conclusion
N
H
S
F
F
I
NH2
N
S
In conclusion, we have developed a nanocrystalline CuO cata-
lyzed coupling of 2-iodoaniline, carbon disulfide, and nitrogen
nucleophile under ligand-free conditions in good yields. This new
coupling reaction underlines the potential of using nanocrystalline
CuO as userfriendly, inexpensive, and efficient catalyst for the cou-
pling of C–S. The catalyst can be easily recovered and reused.
HN
N
BOC
N
N BOC
I
NH2
N
S
NH
N
80b
7
I
NH2
NH2
N
N
S
8
9
0
1
N
55a
75b
70a
70a
N
H
Acknowledgments
I
NH2
2
H N
N
S
We are grateful to CSIR, New Delhi, for research fellowships to
G.S., K.H.V.R., K.K. and to the UGC, New Delhi, for fellowship to K.R.
NH
I
NH2
N
N
1
1
Supplementary data
N
H
S
I
NH2
I
N
N
N
H
S
Cl
S
Cl
NH2
I
N
S
N
S
1
2
70a
N
H
References and notes
a
1. For a brief review, see: (a) Armstrong, A.; Collins, J. C. Angew. Chem. 2010, 122,
2
Reaction conditions: A mixture of 2-iodoaniline (0.5 mmol), CS (0.6 mmol), an
2332; (b) Armstrong, A.; Collins, J. C. Angew. Chem., Int. Ed. 2010, 49, 2282.
N-nucleophile (0.6 mmol), CuO nanoparticles (0.5 mmol), and KOH (1.5–2 mmol) in
2.
HIV = human immunodeficiency virus: Massari, S.; Daelemans, D.; Barreca, M.
L.; Knezevich, A.; Sabatini, S.; Cecchetti, V.; Marcello, A.; Pannecouque, C.;
Tabarrini, O. J. Med. Chem. 2010, 53, 641.
DMSO (3 mL) was stirred at 110 °C for 6 h.
b
2
Reaction conditions: A mixture of an N-nucleophile (0.6 mmol), CS (0.6 mmol),
KOH (1.5–2 mmol) at 0 °C at 3 h after that 2-iodoaniline (0.5 mmol), CuO nano-
particles (0.5 mmol), in DMSO (3 mL) was stirred at 110 °C for 6 h.
3
4
5
.
.
.
PPAR = peroxisome proliferator-activated receptor: Itai, A.; Muto, S.;
Tokuyama, R.; Fukazawa, H.; Ohara, T.; Kato, T. WO 2007023882, 2007.
Black, L. A.; Cowart, M. D.; Gfesser, G. A.; Wakefield, B. D.; Altenbach, R. J.; Liu,
H.; Zhao, C.; Hsieh, G. C. WO 2009085945, 2009.
c
Isolated yields.
Tehim, A.; Herbert, B.; Nguyen, T. M.; Xie, W.; Gauss, C. M. WO 2004029050,
2
004.
Table 2
a
6. Soneda, T.; Takeshita, H.; Kagoshima, Y.; Yamamoto, Y.; Hosokawa, T.; Konosu,
T.; Masuda, N.; Uchida, T.; Achiwa, I.; Kuroyanagi, J.; Fujisawa, T.; Yokomizo, A.;
Noguchi, T. WO 2009084614, 2009.
7. (a) Stewart, G. W.; Baxter, C. A.; Cleator, E.; Sheen, F. J. J. Org. Chem. 2009, 74,
3229; (b) Caleta, I.; Kralj, M.; Marjanovic, M.; Bertosa, B.; Tomic, S.; Pavlovic, G.;
Karminski Zamola, G. J. Med. Chem. 2009, 52, 1744. and references therein.
Recyclability of CuO nanoparticles
NH2
+
I
N
S
NH2
CS2
+
NH
o
KOH DMSO 6h, 110 C
8
.
Saha, P.; Ramana, T.; Purkait, N.; Ali, M. A.; Paul, R.; Punniyamurthy, T. J. Org.
Chem. 2009, 74, 8719.
(a) Cho, S. H.; Kim, J. Y.; Lee, S. Y.; Chang, S. Angew. Chem. 2009, 121, 9291; (b)
Cho, S. H.; Kim, J. Y.; Lee, S. Y.; Chang, S. Angew. Chem., Int. Ed. 2009, 48, 9127;
Recycles
Yieldb (%)
Catalyst recovery (%)
9.
Native
2
3
80
77
75
97
95
92
(
c) Monguchi, D.; Fujiwara, T.; Mori, A. Org. Lett. 2009, 11, 1607.
0. For a brief review, see: Armstrong, A.; Collins, J. C. Angew. Chem. 2010, 122,
332.
1
1
1
1
2
a
2
Reaction conditions: A mixture of an N-nucleophile (0.6 mmol), CS (0.6 mmol),
1. (a) Joyce, L. L.; Batey, R. A. Org. Lett. 2009, 11, 2792; (b) Inamoto, K.; Hasegawa,
C.; Hiroya, K.; Doi, T. Org. Lett. 2008, 10, 5147.
2. Ma, D.; Lu, X.; Shi, L.; Zhang, H.; Jiang, Y.; Liu, X. Angew. Chem., Int. Ed. 2011, 50,
1118–1121.
KOH (1.5–2 mmol) at 0 °C for 3 h after that 2-iodoaniline (0.5 mmol), CuO nano-
particles (0.5 mmol), in DMSO (3 mL) was stirred at 110 °C for 6 h.
b
Isolated yield.
3. (a) Swapna, K.; Murthy, S. N.; Nageswar, Y. V. D. Eur. J. Org. Chem. 2010, 6, 678;
(
1
b) Swapna, K.; Murthy, S. N.; Nageswar, Y. V. D. Eur. J. Org. Chem. 2011, 10,
940; (c) Murthy, S. N.; Madhav, B.; Reddy, V. P.; Nageswar, Y. V. D. Eur. J. Org.
CuO nanoparticles were analyzed by TEM analysis. It was observed
from the TEM studies that the used CuO nanoparticles were intact
in size and shape even after three cycles as compared to the native
catalyst (Fig. 2).
Chem. 2009, 34, 5902; (d) Reddy, K. H. V.; Reddy, V. P.; Shankar, J.; Madhav, B.;
Kumar, B. S. P. A.; Nageswar, Y. V. D. Tetrahedron Lett. 2011, 52, 2679; (e) Reddy,
K. H. V.; Reddy, V. P.; Madhav, B.; Shankar, J.; Nageswar, Y. V. D. Synlett 2011,
1268; (f) Reddy, K. H. V.; Reddy, V. P.; Kumar, A. A.; Kranthi, G.; Nageswar, Y. V.