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3.2.10. N-(3-Methylphenyl)thiobenzamide (1j)
3.3.9. 5-Methyl-2-phenylbenzothiazole (2j)
White needles. Yield: 0.07 g, 71% from 1j; mp 147–148 ꢁC (lit.20
150–151 ꢁC).
Yellow feathers. Yield: 0.14 g, 65% from m-toluidine; mp 80–
81 ꢁC. (Found: C, 73.90; H, 5.83; N, 6.13%. Anal. Calcd for
C
14H13NS: C, 73.97; H, 5.76; N, 6.16%); nmax/cmꢂ1 3175, 1607,
1357; dH 2.37 (3H, s, CH3), 7.08 (1H, d, J 7.5, 4-H), 7.24–7.52 (6H,
m, 2,5,6-H and 30,40,50-H), 7.80 (2H, m, 20,60-H), 9.03 (1H, s, N–H);
dC 21.4, 120.9, 124.3, 126.7, 127.8, 128.6, 128.9, 131.2, 138.9, 139.1,
143.1, 198.4.
3.3.10. 6-Methyl-2-phenylbenzothiazole (2k)
Fine white crystals. Yield: 0.08 g, 84% from 1k; mp 118–119 ꢁC
(lit.21 121–122 ꢁC).
3.3.11. 2-Phenylbenzothiazole (2l)
White needles. Yield: 0.05 g, 46% from 1l; mp 111–112 ꢁC (lit.17
3.2.11. N-(4-Methylphenyl)thiobenzamide (1k)
Yellow feathers. Yield: 0.15 g, 73% from p-toluidine; mp 129–
130 ꢁC (lit.16 128–129.5 ꢁC).
114 ꢁC).
3.3.12. 4-Bromo-2-phenylbenzothiazole (2m)
White needles. Yield 0.04 g, 42% from 1m; mp 91–92 ꢁC. (Found:
C, 53.96; H, 2.88; N, 4.71%. Anal. Calcd for C13H8NSBr: C, 53.81; H,
2.78; N, 4.83%); nmax/cmꢂ1 1479, 972, 757, 685; dH 7.23 (1H, d, J 7.8,
5-H), 7.50 (3H, m, 30,40,50-H), 7.70 (1H, dd, J 1.1 and 7.8, 6-H), 7.81
(1H, dd, J 1.1 and 8.0, 7-H), 8.11 (2H, m, 20,60-H); dC 116.9, 120.8,
126.0, 127.8, 129.0, 129.8, 131.4, 133.2, 135.9, 152.3, 168.6.
3.2.12. N-Phenylthiobenzamide (1l)
Yellow needles. Yield: 0.18 g, 80% from aniline; mp 97–98 ꢁC
(lit.5 115–116 ꢁC).
3.2.13. N-(2-Bromophenyl)thiobenzamide (1m)
Fine yellow crystals. Yield: 0.13 g, 75% from o-bromoaniline; mp
61–62 ꢁC (lit.17 85–86 ꢁC).
3.4. Reaction of thiobenzamides with CAN
3.2.14. N-(4-Nitrophenyl)thiobenzamide (1n)
Yellow needles. Yield: 0.12 g, 63% from p-nitroaniline; mp 143–
144 ꢁC (lit.18 145–146 ꢁC).
To a solution of the thiobenzamide (0.10 g) in acetonitrile (6 mL)
was added a solution of CAN (1.1 mol equiv) in water (4 mL). The
mixture was then stirred at room temperature for 30 min, extracted
into EtOAc (2ꢀ10 mL), dried, evaporated in vacuo, and then purified
by column chromatography.
3.3. Reaction of thiobenzamides with PIFA
3.4.1. N-(4-Methoxy-3,6-dioxocyclohexa-1,4-dien-1-yl)-
benzamide (3)
To a solution of the thiobenzamide (0.10 g) in CF3CH2OH
(1 mL) under an atmosphere of nitrogen was added PIFA
(1.1 mol equiv). The mixture was then stirred at room tempera-
ture for 30 min, evaporated in vacuo and then purified by column
chromatography. The benzothiazoles were recrystallized from
ethanol.
Orange solid. Yield: 0.05 g, 60% from 1d; mp 246–247 ꢁC
(decomp.). (Found: C, 65.52; H, 4.26; N, 5.41%. Anal. Calcd for
C
14H11NO4: C, 65.37; H, 4.31; N, 5.44%); nmax/cmꢂ1 3395, 3052,
1649; dH 3.89 (3H, s, OCH3), 6.59 (1H, s, 3-H), 7.53 (3H, m, 30,40,50-H),
7.87 (2H, m, 20,60-H), 8.29 (1H, s, 6-H), 8.43 (1H, s, N–H); dC 56.5,
97.4, 105.3, 120.8, 127.0, 128.8, 131.7, 135.1, 142.4, 142.8, 145.1.
3.3.1. 4-Methoxy-2-phenylbenzothiazole (2a)
White feathers. Yield: 0.05 g, 50% from 1a; mp 99–100 ꢁC (lit.2
103–104 ꢁC).
Acknowledgements
We gratefully acknowledge support of N.D.-R. by a University of
the West Indies (UWI) Research Fellowship.
3.3.2. 4,7-Dimethoxy-2-phenylbenzothiazole (2b)
White needles. Yield: 0.05 g, 52% from 1b; mp 118–119 ꢁC (lit.13
122–124 ꢁC).
References and notes
3.3.3. 4,6-Dimethoxy-2-phenylbenzothiazole (2c)
White needles. Yield: 0.04 g, 41% from 1c; mp 125–126 ꢁC (lit.19
125–127 ꢁC).
1. Bradshaw, T. D.; Wrigley, S.; Shi, D.; Schultz, R. J.; Paull, K. D.; Stevens, M. F. G. Br.
J. Cancer 1998, 77, 745.
2. Stevens, M. F. G.; McCall, C. J.; Lelieveld, P.; Alexander, P.; Richter, A. J. Med.
Chem. 1994, 37, 1689.
3. Jacobson, P. Chem. Ber. 1886, 19, 1067.
4. Bose, D. S.; Idrees, M. J. Org. Chem. 2006, 71, 8261.
3.3.4. 6-Bromo-4,7-dimethoxy-2-phenylbenzothiazole (2e)
White needles. Yield: 0.03 g, 26% from 1e; mp 120–121 ꢁC (lit.13
123–125 ꢁC).
5. Mu, X.; Zou, J.; Zeng, R.; Wu, J. Tetrahedron Lett. 2005, 46, 4345.
6. Bose, D. S.; Idrees, M. Tetrahedron Lett. 2007, 48, 669.
7. Downer-Riley, N. K.; Jackson, Y. A. Tetrahedron 2007, 63, 10276.
8. Ramsden, C. A.; Rose, H. L. J. Chem. Soc., Perkin Trans. 1 1995, 615.
9. Kita, Y.; Takada, T.; Tohma, H. Pure Appl. Chem. 1996, 68, 627.
10. Kita, Y.; Takada, T.; Mihara, S.; Tohma, H. Synlett 1995, 211.
11. (a) Chu, C.-M.; Gao, S.; Sastry, M. N. V.; Kuo, C.-W.; Lu, C.; Liu, J.-T.; Yao, C.-F.
Tetrahedron 2007, 63, 1863; (b) Hwu, J. R.; King, K.-Y. Curr. Sci. 2001, 8, 1043; (c)
Nair, V.; Matthew, J.; Prabhakaran, J. Chem. Soc. Rev. 1997, 127.
12. (a) Jacob, P.;Callery, P. S.;Shulgin,A. T.;Castagnoli, N.J.Org.Chem.1976, 41, 3627;(b)
Radeke, H. S.; Digits, C. A.; Bruner, S. D.; Snapper, M. L. J. Org. Chem. 1997, 62, 2823.
13. Lyon, M. A.; Lawrence, S.; Williams, D. J.; Jackson, Y. A. J. Chem. Soc., Perkin Trans.
1 1999, 437.
3.3.5. 5-Methoxy-2-phenylbenzothiazole (2f)
Fine white crystals. Yield: 0.07 g, 71% from 1f; mp 75–77 ꢁC
(lit.14 75–77 ꢁC).
3.3.6. 6-Methoxy-2-phenylbenzothiazole (2g)
White feathers. Yield: 0.07 g, 73% from 1g; mp 113–114 ꢁC (lit.2
114–115 ꢁC).
14. Downer, N. K.; Jackson, Y. A. Org. Biomol. Chem. 2004, 2, 3039.
15. Poor-Barltork, I. M.; Khodaei, M. M.; Nikoofar, K. Tetrahedron Lett. 2003, 44, 591.
16. Yonemoto, K.; Shibuya, I.; Tsuchiya, T.; Yasumoto, M.; Taguchi, Y. Bull. Chem. Soc.
Jpn. 1990, 63, 2933.
17. Bunnett, J. F.; Hrutfiord, B. F. J. Am. Chem. Soc. 1961, 83, 1691.
18. Okamoto, K.; Yamamoto, T.; Kanbara, T. Synlett 2007, 2687.
19. Charrier, J.; Landreau, C.; Deniaud, D.; Reliquet, F.; Reliquet, A.; Meslin, J. C.
Tetrahedron 2001, 57, 4195.
3.3.7. 5,6-Dimethoxy-2-phenylbenzothiazole (2h)
White needles. Yield: 0.10 g, 98% from 1h; mp 145–146 ꢁC (lit.2
142–144 ꢁC).
3.3.8. 4-Methyl-2-phenylbenzothiazole (2i)
Fine white crystals. Yield: 0.08 g, 77% from 1i; mp 123–124 ꢁC
(lit.19 124–125 ꢁC).
20. Perry, R. J.; Wilson, B. D. Organometallics 1994, 13, 3346.
21. Perregaard, J.; Lawesson, S. O. Acta Chem. Scand., Ser. B 1977, 31, 203.