F. Yao et al. / Journal of Organometallic Chemistry 723 (2013) 137e142
139
3H), 7.34 (d, J ¼ 8.8 Hz, 2H); 13C NMR (100 MHz, CDCl3):
2.2.22. N-(5-Chlorobenzo[d][1,3]oxathiol-2-ylidene)-4-
d
¼ 21.0, 111.1, 122.2, 122.3, 122.4, 127.9, 129.7, 130.2, 134.6,
methylbenzenamine, 3v
146.5, 148.3, 161.2.
White solid [37], mp 120e122 ꢀC. 1H NMR (400 MHz, CDCl3):
¼ 2.35 (s, 3H), 6.94 (d, J ¼ 8.0 Hz, 2H), 7.10e7.23 (m, 5H); 13C NMR
d
2.2.14. N-(5-methylbenzo[d][1,3]oxathiol-2-ylidene)
cyclohexanamine, 3n
(100 MHz, CDCl3):
d
¼ 21.0, 112.1, 120.6, 121.9, 124.6, 127.2, 129.7,
130.3, 134.8, 145.0, 148.9, 159.0.
White solid [10], mp 73e75 ꢀC. 1H NMR (400 MHz, CDCl3):
d
¼ 1.26e1.50 (m, 5H), 1.59e1.64 (m, 1H), 1.76e1.82 (m, 4H), 2.32 (s,
3H), 2.80e2.85 (m, 1H), 6.93e7.04 (m, 2H), 7.09 (s, 1H); 13C NMR
(100 MHz, CDCl3):
2.2.23. N-(5-Chlorobenzo[d][1,3]oxathiol-2-ylidene)-4-
methoxybenzenamine, 3w
d
¼ 20.9, 24.5, 25.5, 33.1, 63.4, 110.6, 122.3, 122.6,
White solid [37], mp 100e102 ꢀC. 1H NMR (400 MHz, CDCl3):
127.4, 133.6, 148.2, 156.4.
d
¼ 3.81 (s, 3H), 6.93 (d, J ¼ 8.8 Hz, 2H), 7.01 (d, J ¼ 8.8 Hz, 2H), 7.13
(d, J ¼ 8.4 Hz, 1H), 7.18 (d, J ¼ 8.4 Hz, 1H), 7.24 (s, 1H); 13C NMR
2.2.15. N-(5-tert-Butylbenzo[d][1,3]oxathiol-2-ylidene)
benzenamine, 3o
(100 MHz, CDCl3):
d
¼ 55.4, 112.1, 114.9, 121.8, 121.9, 124.5, 127.2,
129.6, 140.7, 148.9, 157.1, 158.9.
White solid [10], mp 56e58 ꢀC. 1H NMR (400 MHz, CDCl3):
d
¼ 1.30 (s, 9H), 7.06 (d, J ¼ 7.6 Hz, 2H), 7.16 (t, J ¼ 8.0 Hz, 2H), 7.25
2.2.24. N-(5-Chlorobenzo[d][1,3]oxathiol-2-ylidene)-4-
nitrobenzenamine, 3x
(d, J ¼ 8.0 Hz, 1H), 7.27 (s, 1H), 7.38 (t, J ¼ 7.6 Hz, 2H); 13C NMR
(100 MHz, CDCl3):
124.9, 129.6, 148.0, 148.1, 148.3, 160.7.
d
¼ 31.4, 34.8, 110.7, 118.9, 120.9, 122.3, 124.3,
Yellow solid [37], mp 171e173 ꢀC. 1H NMR (400 MHz, DMSO-d6):
d
¼ 7.29 (d, J ¼ 7.6 Hz, 2H), 7.35e7.43 (m, 2H), 7.74 (s, 1H), 8.25 (d,
J ¼ 8.4 Hz, 2H); 13C NMR (100 MHz, DMSO-d6):
d
¼ 112.7, 122.0,
2.2.16. N-(5-tert-Butylbenzo[d][1,3]oxathiol-2-ylidene)-4-
methylbenzenamine, 3p
122.7, 123.9, 125.4, 127.6, 129.0, 144.2, 148.8, 152.8, 160.9.
White solid [10], mp 81e83 ꢀC. 1H NMR (400 MHz, CDCl3)
2.2.25. N-(5-Chlorobenzo[d][1,3]oxathiol-2-ylidene)-4-
chlorobenzenamine, 3y
d
¼ 1.30 (s, 9H), 2.35 (s, 3H), 6.97 (d, J ¼ 8.0 Hz, 2H), 7.14 (d,
J ¼ 8.0 Hz, 1H), 7.18 (d, J ¼ 7.6 Hz, 2H), 7.24 (d, J ¼ 8.0 Hz,
1H), 7.26 (s, 1H); 13C NMR (100 MHz, CDCl3)
21.0, 31.5, 34.8,
White solid [37], mp 116e118 ꢀC. 1H NMR (400 MHz, CDCl3):
d
d
¼ 6.98 (d, J ¼ 8.0 Hz, 2H), 7.15 (d, J ¼ 8.8 Hz, 1H), 7.23 (d, J ¼ 8.8 Hz,
110.7, 118.9, 120.8, 122.4, 124.2, 130.2, 134.4, 145.5, 147.9, 148.2,
160.4.
1H), 7.27 (s, 1H), 7.34 (d, J ¼ 8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3):
d
¼ 112.3, 122.0, 122.3, 124.2, 127.4, 129.9, 130.1, 130.5, 146.1, 148.9,
160.1.
2.2.17. N-(5-tert-Butylbenzo[d][1,3]oxathiol-2-ylidene)-4-
methoxybenzenamine, 3q
2.3. Recycling of ionic liquid and catalytic system
White solid [10], mp 99e101 ꢀC. 1H NMR (400 MHz, CDCl3)
d 1.31
(s, 9H), 3.81 (s, 3H), 6.92 (d, J ¼ 8.8 Hz, 2H), 7.02 (d, J ¼ 8.8 Hz, 2H),
After completion of the reaction, the reaction mixture was
cooled to 25 ꢀC and extracted with diethyl ether (3 ꢁ 10 mL). The
remaining oily ionic liquid containing CuI/1,10-phenanthroline
complex was concentrated in vacuo (5.0 torr/r.t. for 1 h) and
a second amount of reactants were added and the process was
repeated up to 3 times. After third cycle, the ionic liquid was
washed with distilled water (2 ꢁ 10 mL), dried in vacuo (5.0 Torr/
80 ꢀC for 1 h) and recycled for another three times without addition
of CuI and 1,10-phenanthroline.
7.14 (d, J ¼ 8.8 Hz, 1H), 7.25 (d, J ¼ 8.4 Hz, 1H), 7.27 (s, 1H); 13C NMR
(100 MHz, CDCl3)
d 31.4, 34.7, 55.4, 110.6, 114.8, 118.9, 122.0, 122.3,
124.2, 141.2, 147.9, 148.2, 156.9, 160.3.
2.2.18. N-(5-tert-Butylbenzo[d][1,3]oxathiol-2-ylidene)-4-
nitrobenzenamine, 3r
Yellow solid [37], mp 134e136 ꢀC. 1H NMR (400 MHz, CDCl3):
d
¼ 1.33 (s, 9H), 7.18e7.36 (m, 5H), 8.26 (d, J ¼ 8.8 Hz, 2H); 13C NMR
(100 MHz, CDCl3):
125.5, 144.6, 148.2, 148.7, 153.7, 162.1.
d
¼ 31.4, 34.8, 111.0, 119.1, 121.7, 122.3, 124.8,
3. Results and discussion
2.2.19. N-(5-tert-Butylbenzo[d][1,3]oxathiol-2-ylidene)-4-
chlorobenzenamine, 3s
Our choice of solvent was the readily prepared and hydrophobic
1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]).
In our preliminary experiments, the reaction of 2-iodophenol with
phenyl isothiocyanate was chosen as a model reaction. The influ-
ences of various reaction parameters such as copper salts, ligands,
and bases on the reaction were tested and the results are
summarized in Table 1. Among the copper salts such as CuI, CuBr,
CuCl, Cu2O, CuCl2, CuSO4 and Cu(OAc)2 screened in the reaction, CuI
was found to be the most effective catalyst, leading to the desired
product in 97% yield (Table 1, entry 1). In a blank experiment, the
reaction did not occur in the absence of copper catalyst (entry 12).
And then, we investigated the influences of various ligands such as
White solid [37], mp 94e96 ꢀC. 1H NMR (400 MHz, CDCl3)
d 1.23
(s, 9H), 6.92 (d, J ¼ 8.8 Hz, 2H), 7.07 (d, J ¼ 8.4 Hz, 1H), 7.17e7.25 (m,
4H); 13C NMR (100 MHz, CDCl3)
d
30.4, 33.7, 109.7,117.9, 121.0, 121.3,
123.4, 128.7, 129.0, 145.5, 147.1, 160.2.
2.2.20. N-(5-tert-Butylbenzo[d][1,3]oxathiol-2-ylidene)
cyclohexanamine, 3t
White solid [10], mp 52e54 ꢀC. 1H NMR (400 MHz, CDCl3):
d
¼ 1.29 (s, 9H), 1.31e1.52 (m, 4H), 1.59e1.65 (m, 2H), 1.76e1.83
(m, 4H), 2.81e2.87 (m, 1H), 7.04 (d, J ¼ 8.4 Hz, 1H), 7.20 (d,
J ¼ 8.8 Hz, 1H), 7.31 (s, 1H); 13C NMR (100 MHz, CDCl3):
d
¼ 24.5,
1,10-phenanthroline,
L-proline, N,N-dimethylglycine, glycine and
25.6, 31.5, 33.1, 34.7, 63.3, 110.4, 118.9, 122.4, 124.0, 147.2, 148.0,
156.5.
acac on the model reaction.
L
-Proline, glycine and acac were not
suitable for this process. N,N-Dimethylglycine was good, but 1,10-
phenanthroline was the best choice. Hardly any desired product
was observed without a ligand (entry 13). Among the bases
examined, Cs2CO3 was found to be the most effective (Table 1, entry
1), K2CO3 and K3PO4 also afforded good yields (Table 1, entries 14
and 16), but Na2CO3 was substantially less effective (Table 1, entry
15). Therefore, the optimized conditions for this tandem reaction
2.2.21. N-(5-Chlorobenzo[d][1,3]oxathiol-2-ylidene)benzenamine, 3u
White solid [10], mp 106e108 ꢀC. 1H NMR (400 MHz, CDCl3):
d
¼ 7.04 (d, J ¼ 7.6 Hz, 2H), 7.12e7.25 (m, 4H), 7.38 (t, J ¼ 7.6 Hz, 2H);
13C NMR (100 MHz, CDCl3):
¼ 112.2, 120.8, 121.9, 122.8, 124.5,
125.2, 127.3, 129.7, 147.6, 148.9, 159.4.
d