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S. Zhou et al. / Dyes and Pigments 86 (2010) 123e128
2.3.5. 3-(20-benzothiazolyl)-7-(diethylamino)-2H-1-benzopyran-2-
one (4e)
R
O
O
N
Yield 60%; orange solid; mp 213e215 ꢁC; 1H NMR (500 MHz,
: 8.91 (s, 1H, 4-H), 8.02 (d, J ¼ 8.2 Hz, 1H, 70-H), 7.94 (d,
X
CDCl3)
d
J ¼ 7.9 Hz, 1H, 40-H), 7.50e7.48 (m, 2H, 50-H, 60-H), 7.36 (t, J ¼ 7.6 Hz,
1H, 5-H), 6.67 (dd, J6,5 ¼ 8.9 Hz and J6,8 ¼ 2.3 Hz, 1H, 6-H), 6.57 (d,
J ¼ 2.2 Hz, 1H, 8-H), 3.46 (q, J ¼ 7.1 Hz, 4H, NCH2CH3), 1.26 (t,
J ¼ 7.1 Hz, 6H, NCH2CH3); ESI-MS: 351.6 [M þ H]þ; HR-ESI-MS for
C20H19N2O2S: Found: 351.1170; Calcd. 351.1162.
X=O, S, N
Fig. 1. Typical coumarin fluorescent dyes.
2.2. Synthesis of 2-benzothiazolyl phenol (B)
2.3.6. 3-(50-chloro-20-benzothiazolyl)-2H-1-benzopyran-2-one (4f)
Yield 58%; yellow solid; mp 271e273 ꢁC; 1H NMR (500 MHz,
A mixture of salicylaldehyde (2 mmol), ethyl cyanoacetate
(2 mmol) and o-aminophenol (2 mmol) in n-butanol (20 mL)
containing benzoic acid (0.6 mmol) was refluxed for 7 h. After the
solution was cooled, the solid was filtered and washed with water
affording a pale yellow solid. Yield 65%; mp 132e133 ꢁC; 1H NMR
CDCl3)
d
: 9.08 (s, 1H, 4-H), 8.07 (d, J ¼ 1.9 Hz, 1H, 40-H), 7.90 (d,
J ¼ 8.5 Hz, 1H, 70-H), 7.75 (d, J ¼ 7.7 Hz, 1H, 5-H), 7.67 (t, J ¼ 8.6 Hz,
1H, 7-H), 7.46 (d, J ¼ 8.3 Hz, 1H, 60-H), 7.42e7.39 (m, 2H, 6-H, 8-H);
EI-MS: 313.1 [M]þ; HR-EI-MS for C16H8ClNO2S: Found: 312.9963;
Calcd. 312.9964.
(500 MHz, CDCl3)
d
: 12.50 (s, 1H, ArOH), 7.97(d, J ¼ 8.2 Hz,1H, 70-H),
7.89 (d, J ¼ 7.5 Hz, 1H, 40-H), 7.67 (d, J ¼ 7.8 Hz, 1H, 60-H), 7.49 (t,
J ¼ 8.1 Hz, 1H, 50-H), 7.41e7.36 (m, 2H, 3-H, 5-H), 7.10 (d, J ¼ 8.3 Hz,
2.3.7. 6-chloro-3-(50-chloro-20-benzothiazolyl)-2H-1-
benzopyran-2-one (4g)
1H, 4-H), 6.95 (t, J ¼ 7.7 Hz, 1H, 6-H); 13C NMR (500 MHz, CDCl3)
d:
Yield 48%; yellow solid; mp 296e297 ꢁC; 1H NMR (500 MHz,
169.4, 158.0, 151.9, 132.7, 132.6, 128.4, 126.7, 125.5, 122.2, 121.5,
CDCl3)
d
: 8.99 (s, 1H, 4-H), 8.08 (d, J ¼ 2.0 Hz, 1H, 40-H), 7.89 (d,
119.5, 117.9, 116.8; ESI-MS: 228.0 [M þ H]þ.
J ¼ 8.6 Hz, 1H, 700-H), 7.72 (d, J ¼ 2.4 Hz, 1H, 5-H), 7.60 (dd,
0
0
0
J6 ,7 ¼ 8.7 Hz and J6 ,4 ¼ 2.4 Hz, 1H, 60-H), 7.43e7.40 (m, 2H, 7-H, 8-
H); EI-MS: 347.1 [M þ H]þ; HR-EI-MS for C16H8Cl2NO2S: Found:
346.9580; Calcd. 346.9575.
2.3. General procedure for the synthesis of compounds 4ae4j
A mixture of salicylaldehyde (2 mmol), ethyl 2-cyanoacetate
(4 mmol) and o-aminophenol (2 mmol) in ethanol (20 mL) con-
taining piperidine (0.3 mmol) was refluxed for 7 h. After the solu-
tion was cooled, the solid was filtered, washed with water and then
recrystallized from DMF-H2O to afford the solid 4ae4j.
2.3.8. 6-bromo-3-(50-chloro-20-benzothiazolyl)-2H-1-
benzopyran-2-one (4h)
Yield 50%; yellow solid; mp 295e297 ꢁC; 1H NMR (500 MHz,
CDCl3)
d
: 8.99 (s, 1H, 5-H), 8.08 (d, J ¼ 1.9 Hz, 1H, 4-H), 7.91 (d,
J ¼ 8.5 Hz, 1H, 70-H), 7.88 (d, J ¼ 2.3 Hz, 1H, 40-H), 7.74 (dd,
J7,8 ¼ 8.8 Hz and J7,5 ¼ 2.3 Hz, 1H, 7-H), 7.42 (dd, J6’,7’ ¼ 8.6 Hz and
J6’,4’ ¼ 1.9 Hz, 1H, 60-H), 7.35 (d, J ¼ 8.8 Hz, 1H, 8-H); EI-MS: 391.1,
393.1[M þ H]þ; HR-EI-MS for C16H8BrClNO2S: Found: 390.9065,
392.9041; Calcd. 390.9069, 392.9069.
2.3.1. 3-(20 -benzothiazolyl)-2H-1-benzopyran-2-one (4a)
Yield 68%; yellow solid; mp 221e223 ꢁC; 1H NMR (500 MHz,
CDCl3)
d
: 9.09 (s, 1H, 4-H), 8.10 (d, J ¼ 8.2 Hz, 1H, 70-H), 8.00 (d,
J ¼ 7.7 Hz, 1H, 40-H), 7.75 (d, J ¼ 7.8 Hz, 1H, 5-H), 7.65(t, J ¼ 8.5 Hz,
1H, 7-H), 7.55 (t, J ¼ 8.2 Hz,1H, 60-H), 7.46e7.38 (m, 3H, 6-H, 8-H, 50-
H); ESI-MS: 280.5 [M þ H]þ; HR-ESI-MS for C16H10NO2S: Found:
280.0443, Calcd. 280.0432.
2.3.9. 3-(50-chloro-20-benzothiazolyl)-7-methoxy-2H-1-
benzopyran-2-one (4i)
Yield 80%; yellow solid; mp 279e280 ꢁC; 1H NMR (500 MHz,
2.3.2. 3-(20-benzothiazolyl)-6-chloro-2H-1-benzopyran-2-one (4b)
Yield 49%; yellow solid; mp 250e252 ꢁC; 1H NMR (500 MHz,
CDCl3)
d
: 9.02 (s, 1H, 4-H), 8.04 (d, J ¼ 2.0 Hz, 1H, 40-H), 7.87 (d,
J ¼ 8.4 Hz, 1H, 700-H), 7.64 (d, J ¼ 8.7 Hz, 1H, 5-H), 7.38 (dd,
0
0
0
CDCl3)
d
: 9.01 (s, 1H, 4-H), 8.12 (d, J ¼ 8.2 Hz, 1H, 70-H), 8.00 (d,
J6 ,7 ¼ 8.6 Hz and J6 ,4 ¼ 1.9 Hz, 1H, 60-H), 6.97 (dd, J6,5 ¼ 8.7 Hz and
J6,8 ¼ 2.3 Hz, 1H, 6-H), 6.93 (d, J ¼ 2.3 Hz, 1H, 8-H), 3.94 (s, 3H,
CH3O); ESI-MS: 344.5 [M þ H]þ; HR-ESI-MS for C17H11ClNO3S:
Found: 344.0140; Calcd. 344.0143.
J ¼ 7.9 Hz, 1H, 40-H), 7.71 (d, J ¼ 2.3 Hz, 1H, 5-H), 7.60e7.56 (m, 2H,
50-H, 60-H), 7.46 (t, J ¼ 7.5 Hz, 1H, 7-H), 7.40 (d, J ¼ 8.8 Hz, 1H, 8-H);
ESI-MS: 314.2 [M þ H]þ; HR-ESI-MS for C16H9ClNO2S: Found:
314.0034, Calcd. 314.0037.
2.3.10. 3-(50-chloro-20-benzothiazolyl)-7-(diethylamino)-2H-1-
benzopyran-2-one (4j)
2.3.3. 3-(20-benzothiazolyl)-6-bromo-2H-1-benzopyran-2-one (4c)
Yield 47%; yellow solid; mp 279e280 ꢁC; 1H NMR (500 MHz,
Yield 58%; orange solid; mp 259e261 ꢁC; 1H NMR (500 MHz,
CDCl3)
d
: 9.00 (s, 1H, 5-H), 8.10 (d, J ¼ 8.2 Hz, 1H, 70-H), 8.00 (d,
CDCl3)
d
: 8.90 (s, 1H, 4-H), 7.99 (d, J ¼ 1.9 Hz, 1H, 40-H), 7.83 (d,
J ¼ 8.0 Hz, 1H, 40-H), 7.86 (s, 1H, 4-H), 7.74 (d, J ¼ 8.5 Hz, 1H, 7-H),
7.56 (t, J ¼ 7.4 Hz, 1H, 60-H), 7.46 (t, J ¼ 7.4 Hz, 1H, 50-H), 7.35(d,
J ¼ 8.8 Hz, 1H, 8-H); ESI-MS: 358.4, 360.4 [M þ H]þ; HR-ESI-MS for
C16H9BrNO2S: Found: 357.9516, 359.9504; Calcd. 357.9537,
359.9537.
J ¼ 8.5 Hz, 1H, 700-H), 7.50 (d, J ¼ 9.0 Hz, 1H, 5-H), 7.33 (dd,
0
0
0
J6 ,7 ¼ 8.5 Hz and J6 ,4 ¼ 2.0 Hz, 1H, 60-H), 6.69 (dd, J6,5 ¼ 9.0 Hz and
J6,8 ¼ 2.5 Hz,1H, 6-H), 6.57 (d, J ¼ 2.4 Hz,1H, 8-H), 3.47 (q, J ¼ 7.1 Hz,
4H, NCH2CH3), 1.26 (t, J ¼ 7.1 Hz, 6H, NCH2CH3); ESI-MS: 385.1
[M þ H]þ; HR-ESI-MS for C20H18ClN2O2S: Found: 385.0764; Calcd.
385.0772.
2.3.4. 3-(20-benzothiazolyl)-7-methoxy-2H-1-benzopyran-
2-one (4d)
3. Results and discussion
Yield: 68%; yellow solid; mp 232e235 ꢁC; 1H NMR(500 MHz,
CDCl3)
d
: 9.04 (s, 1H, 4-H), 8.07 (d, J ¼ 8.2 Hz, 1H, 70-H), 7.98 (d,
3.1. One-pot synthesis of 3-(20-benzothiazolyl)coumarins
J ¼ 7.8 Hz, 1H, 40-H), 7.65 (d, J ¼ 8.7 Hz, 1H, 5-H), 7.53 (t, J ¼ 7.1 Hz,
1H, 60-H), 7.42 (t, J ¼ 7.0 Hz, 1H, 50-H), 6.98e6.96 (m, 1H, 6-H), 6.93
(s, 1H, 8-H), 3.94 (s, 3H, CH3O); ESI-MS: 310.5 [M þ H]þ; HR-ESI-MS
for C17H12NO3S: Found: 310.0525; Calcd. 310.0532.
We have ever reported the preparation of 3-(20-benzoxazolyl)
coumarins in good yields by three-component one-pot synthesis
under the catalysis of benzoic acid [19]. In the following work to