J = 7.4), 6.72 (s, 2H), 6.64-6.58 (m, 3H), 6.20 (s, 1H), 3.70 (s,
3H); 13C NMR (75 MHz, CDCl3): d 159.1, 155.8, 154.7, 136.7,
130.9, 129.8, 129.5, 127.9, 127.6, 127.0, 127.0, 126.3, 124.3, 123.6,
121.8, 120.0, 119.4, 119.2, 119.1, 112.8, 110.9, 109.7, 106.0, 55.4,
32.9. MS (ESI): m/z 493 [M - 1]+. Anal. calcd. for C34H26N2O2:
C, 82.57; H, 5.30; N, 5.66. Found: C, 82.69; H, 5.19; N, 5.52.
9-Methoxy-12-(p-tolylthio)-12H-benzo[a]xanthene (20d). As
described for 12a, 11d (100 mg, 0.35 mmol), 4-methylbenzenethiol
(43 mg, 0.35 mmol) and Sc(OTf)3 (10 mol%) furnished 20d (71%,
98 mg) as a colorless solid. M.p. 145–146 ◦C. IR (KBr): 3014,
2360, 1619, 759, 670 cm-1. 1H NMR (300 MHz, CDCl3): d 8.29 (d,
1H, J = 8.1), 7.86 (d, 1H, J = 8.3), 7.73 (d, 1H, J = 8.7), 7.68-7.64
(m, 1H), 7.51-7.46 (m, 1H), 7.24 (s, 1H), 7.07 (d, 1H, J = 9.1), 6.86
(d, 2H, J = 7.5), 6.71 (d, 1H, J = 6.1), 6.61 (d, 2H, J = 7.9), 6.50
(s, 1H) 6.05 (s, 1H), 3.84 (s, 3H), 2.29 (s, 3H). MS (ESI): m/z 261.
Anal. calcd. for C25H20 O2S: C, 78.09; H, 5.24. Found: C, 77.94;
H, 5.38.
((4-Methoxy-2-(naphthalen-2-yloxy)phenyl)methylene)bis((3-
methoxyphenyl)sulfane) (19d). Isolated as a colorless liquid by
silica gel column chromatography (3% ethyl acetate in hexane)
1
of the crude product. IR (KBr): 1614, 760, 678 cm-1. H NMR
(300 MHz, CDCl3): d 7.86-7.82 (m, 2H), 7.78-7.71 (m, 2H), 7.52-
7.42 (m, 2H), 7.25-7.11 (m, 4H), 6.98 (d, 2H, J = 7.7), 6.92-
6.91 (m, 2H), 6.78-6.75 (m, 3H), 6.43 (d, 1H, J = 2.5), 6.10 (s,
1H), 3.72 (s, 3H), 3.67 (s, 6H); 13C NMR (75 MHz, CDCl3): d
160.3,159.5, 154.6, 154.3, 136.0, 134.2, 130.2, 130.1, 129.8, 129.5,
127.6, 127.2, 126.5, 124.8, 124.1, 123.0, 119.5, 116.7, 114.1, 113.7,
109.9, 104.7, 55.4, 55.1, 52.5. MS (ESI): m/z 261, 262. Anal. calcd.
for C32H28S2O4: C, 71.08; H, 5.22. Found: C, 71.21; H, 5.09.
9-Methoxy-12-(3-methoxyphenylthio)-12H -benzo[a]xanthene
(20e). As described for 12a, 11d (100 mg, 0.35 mmol), 3-
methoxybenzenethiol (49 mg, 0.35 mmol) and Sc(OTf)3(10 mol%)
furn◦ished 20e (76%, 109 mg) as a colorless solid. M.p. 176–
177 C. IR (KBr): 2360, 1617, 762, 679 cm-1. 1H NMR (300 MHz,
CDCl3): d 8.27 (d, 1H, J = 8.5), 7.85 (d, 1H, J = 7.7), 7.72 (d,
1H, J = 9.2), 7.66-7.61 (m, 1H), 7.51-7.48 (m, 1H), 7.30 (d, 1H,
J = 8.5), 7.06 (d, 1H, J = 8.9), 6.92 (d, 1H, J = 7.3), 6.82-6.76
(m, 1H), 6.72 (dd, 1H, J1 = 2.5, J2 = 8.2), 6.47 (d, 1H, J = 2.5),
6.35-6.30 (m, 1H), 6.16-6.14 (m, 1H), 6.12 (s, 1H), 3.81 (s, 3H),
3.40 (s, 3H). MS (ESI): m/z 261. Anal. calcd. for C25H20 O3S: C,
74.98; H, 5.03. Found: C, 75.11; H, 4.91.
12-(3-Methoxyphenylthio)-12H-benzo[a]xanthene (20a). As
described for 12a, 11b (100 mg, 0.40 mmol), 3-methoxy-
benzenethiol (56 mg, 0.40 mmol) and Sc(OTf)3 (10 mol%)
furn◦ished 20a (79%, 117 mg) as a colorless solid. M.p. 161–
162 C. IR (KBr): 2358, 1605, 761, 691 cm-1. 1H NMR (300 MHz,
CDCl3): d 8.31 (d, 1H, J = 8.5), 7.87 (d, 1H, J = 8.0), 7.75 (d,
1H, J = 8.9), 7.72-7.67 (m, 1H), 7.54-7.49 (m, 1H), 7.43 (dd, 1H,
J1 = 1.4, J2 = 7.6), 7.28-7.23 (m, 1H), 7.18-7.12 (m, 1H), 7.09 (d,
1H, J = 8.9), 6.98-6.93 (m, 2H), 6.83 (dd, 1H, J1 = 1.7, J2 = 8.3),
6.34 (d, 1H, J = 7.5), 6.17 (t, 1H, J = 1.8), 6.15 (s, 1H), 3.48 (s,
3H); 13C NMR (75 MHz, CDCl3): d 158.9, 151.8, 150.4, 131.8,
130.7, 130.6, 129.5, 129.4, 129.0, 128.8, 128.7, 128.2, 126.9, 124.4,
123.5, 122.9, 121.3, 120.5, 117.4, 116.2, 115.9, 112.1, 54.9, 44.9.
MS (ESI): m/z 231, 369 [M - 1]+. Anal. calcd. for C24H18O2S: C,
77.81; H, 4.90. Found: C, 77.92; H, 5.02.
2-(12H-Benzo[a]xanthen-12-ylthio)pyridine (20f). As des-
cribed for 12a, 11b (100 mg, 0.40 mmol), pyridine-2-thiol (44 mg,
0.40 mmol) and Sc(OTf)3 (50 mol%) furnished 20f (58%, 77 mg)
as a colorless semisolid. IR (KBr): 2358, 1621, 759 cm-1. 1H NMR
(300 MHz, CDCl3): d 8.39 (d, 1H, J = 8.5), 7.86 (d, 2H, J = 8.6),
7.72 (d, 1H, J = 7.6), 7.63 (d, 1H, J = 7.1), 7.52–6.72 (m, 9H),
6.54 (d, 1H, J = 7.1). MS (ESI): m/z 231 [M - 110]+. Anal. calcd.
for C22H15NOS: C, 77.39; H, 4.43, N, 4.10. Found: C, 77.51; H,
4.27; N, 3.98.
12-(Phenylthio)-12H-benzo[a]xanthene (20b). As described for
12a, 11b (100 mg, 0.40 mmol), benzenethiol (44 mg, 0.40 mmol)
and Sc(OTf)3 (10 mol%) furnished 20a (72%, 98 mg) as a colorless
solid. M.p. 199–200 ◦C. IR (KBr): 3015, 2361, 1609, 771, 691 cm-1.
1H NMR (300 MHz, CDCl3): d 8.32 (d, 1H, J = 8.3), 7.87 (d, 1H,
J = 8.1), 7.75 (d, 1H, J = 8.9), 7.71-7.67 (m, 1H), 7.54-7.49 (m,
1H), 7.41-7.38 (m, 1H), 7.29-7.22 (m, 2H), 7.16-7.02 (m, 4H), 6.95
(d, 1H, J = 8.0), 6.70 (d, 2H, J = 7.6), 6.13 (s, 1H); 13C NMR
(75 MHz, CDCl3): d 151.7, 150.4, 136.8, 132.4, 130.9, 130.7, 130.6,
130.1, 129.4, 129.4, 128.9, 128.7, 128.2, 128.1, 126.9, 124.4, 123.5,
122.9, 121.3, 117.4, 115.9, 112.1, 44.8. MS (ESI): m/z 231. Anal.
calcd. for C23H16OS: C, 81.14; H, 4.74. Found: C, 81.02; H, 4.61.
Acknowledgements
This research project was supported by the Department of Science
and Technology (DST), New Delhi, India. Ritesh thanks CSIR,
New Delhi, India for providing a fellowship. Experimental help
from Miss Nancy Gupta is acknowledged.
Notes and references
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19, 1759; (b) Y. Oikawa, H. Hirasawa and O. Yonemitsu, Chem. Pharm.
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(d) L. F. Tietze and U. Beifuss, Angew. Chem., Int. Ed. Engl., 1993, 32,
131; (e) L. F. Tietze, Chem. Rev., 1996, 96, 115.
12-(Naphthalen-2-ylthio)-12H-benzo[a]thioxanthene (20c). As
described for 12a, 11c (100 mg, 0.37 mmol), naphthalene-2-thiol
(59 mg, 0.37 mmol) and Sc(OTf)3 (10 mol%) furnished 20c (74%,
113 mg) as a colorless solid. M.p. 218–219 ◦C IR (KBr): 3011,
2361, 1621, 769, 671 cm-1. 1H NMR (300 MHz, CDCl3): d 8.28 (d,
1H, J = 8.5), 7.85-7.62 (m, 7H), 7.51-7.42 (m, 5H), 7.34 (d, 1H, J =
8.5), 7.25-7.17 (m, 1H), 7.97-6.89 (m, 1H), 6.79 (d, 1H, J = 7.6),
6.40 (s, 1H); 13C NMR (75 MHz, CDCl3): d 136.5, 133.3, 132.9,
132.9, 132.8, 132.6, 132.5, 132.1, 131.0, 130.3, 129.3, 128.9, 128.0,
127.9, 127.8, 127.5, 127.2, 127.1, 126.9, 126.7, 126.2, 125.8, 125.3,
124.8, 121.8, 51.4. MS (ESI): m/z 247. Anal. calcd. for C27H18S2:
C, 79.76; H, 4.46. Found: C, 79.89; H, 4.58.
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1104 | Org. Biomol. Chem., 2010, 8, 1097–1105
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