Download PDF
Synlett 2005(10): 1612-1614  
DOI: 10.1055/s-2005-869841
LETTER
© Georg Thieme Verlag Stuttgart · New York

Oxidative Cyclization of Thiobenzanilides to Benzothiazoles Using N-Benzyl-DABCO Tribromide under Mild Conditions

Firouz Matloubi Moghaddam*, Hassan Zali Boeini
Sharif University of Technology, Department of Chemistry, PO Box 11365-9516 Tehran, Iran
e-Mail: matloubi@sharif.edu;
Further Information

Publication History

Received 4 March 2005
Publication Date:
12 May 2005 (online)

    Permissions and Reprints All articles of this category

Abstract

N-benzyl-DABCO tribromide, a stable, crystalline organic ammonium tribromide (OATB), have been used as an alternative electrophilic bromine source for the efficient oxidative cyclization of thiobenzanilides to the corresponding benzothiazoles under mild conditions.

Key words

benzothiazole - N-benzyl-­DABCO-tribromide - oxidative cyclization

    References

  • 1 Das J. Moquin RV. Liu C. Doweyko AM. Defex HF. Fang Q. Pang S. Pitt S. Shen DR. Schieven GL. Barrish JC. Wityak J. Bioorg. Med. Chem. Lett.  2003,  13:  2587 
    CrossrefGoogle Scholar
  • 2 Hays SJ. Rice MJ. Ortwine DF. Johnson G. Schwarz RD. Boyd DK. Copeland LF. Vartanian MG. Boxer PA. J. Pharm. Sci.  1994,  83:  1425 
    CrossrefPubMedGoogle Scholar
  • 3 Jimonet P. Audiau F. Barreau M. Blanchard JC. Boireau A. Bour Y. Coleno MA. Doble A. Doerflinger G. Huu CD. Donat MH. Duchesne JM. Ganil P. Gueremy C. Honore E. Just B. Kerphirique R. Gontier S. Hubert P. Laduron PM. Le Blevec J. Meunier M. Miquet JM. Nemecek C. Pasquet M. Piot O. Pratt J. Rataud J. Reibaud M. Stutzmann JM. Mignani S. J. Med. Chem.  1999,  42:  2828 
    CrossrefPubMedGoogle Scholar
  • 4 He Y. Benz A. Fu T. Wang M. Covey DF. Zorumski CF. Mennerick S. Neuropharmacology  2002,  42:  199 
    CrossrefPubMedGoogle Scholar
  • 5 Bensimon G. Lacomblez L. Meininger V. New Engl. J. Med.  1994,  330:  585 
    CrossrefGoogle Scholar
  • 6 Foscolos G. Tsatsas G. Champagnac A. Pommier M. Ann. Pharm. Fr.  1977,  35:  295 
    Google Scholar
  • 7 Shirke VG. Bobade AS. Bhamaria RP. Khadse BG. Sengupta SR. Indian Drugs  1990,  27:  350 
    Google Scholar
  • 8 Paget CJ. Kisner K. Stone RL. Delong DC. J. Med. Chem.  1969,  12:  1016 
    CrossrefPubMedGoogle Scholar
  • 9 Gong B. Hong F. Kohm C. Bonham L. Klein P. Bioorg. Med. Chem. Lett.  2004,  14:  1455 
    CrossrefGoogle Scholar
  • 10 Hutchinson I. Bradshaw TD. Matthews CS. Stevens MFG. Westwell AD. Bioorg. Med. Chem. Lett.  2003,  13:  471 
    CrossrefGoogle Scholar
  • 11 Ivanov SK. Yuritsyn VS. Neftekhimiya  1971,  11:  99 ; Chem. Abstr. 1971, 74, 124487m
    Google Scholar
  • 12 Monsanto Co. inventors; Brit. Pat.  1,106,577.  ; Chem. Abstr. 1968, 68, 96660t
  • 13 Zhang XH. Wong OY. Gao ZQ. Lee CS. Kwong HL. Lee ST. Wu SK. Mater. Sci. Eng., B  2001,  85:  182 
    CrossrefGoogle Scholar
  • 14 Ranu BC. Jana R. Dey SS. Chem. Lett.  2004,  33:  274 
    CrossrefGoogle Scholar
  • 15a Schwartz H. inventors; Neth. Appl.  6,607,039. 
  • 15b Osuka A. Uno Y. Horiuchi H. Suzuki H. Synthesis  1984,  145 
    Google Scholar
  • 15c Saikachi H. Hisano T. Chem. Pharm. Bull.  1960,  8:  51 
    Google Scholar
  • 15d Compare: Saikachi H. Hisano T. Chem. Pharm. Bull.  1959,  7:  716 
    Google Scholar
  • 16a Hugerschoff H. Chem. Ber.  1901,  34:  3130 
    Google Scholar
  • 16b Hugerschoff H. Chem. Ber.  1903,  36:  3121 
    Google Scholar
  • 17 Sprague JM. Land AH. In Heterocyclic Compounds   Vol. 5:  Eldrenfield RC. J. Wiley; New York: 1958.  Chap. 8. p.484-721  
    Google Scholar
  • 18 Jordan AD. Luo C. Reitz AB. J. Org. Chem.  2003,  68:  8693 
    CrossrefGoogle Scholar
  • 20 Matloubi Moghaddam F. Zali Boeini H. Taheri S. J. Sulfur Chem.  2004,  25:  407 
    Google Scholar
19

Preparation of N -Benzyl-DABCO Tribromide. To a stirred solution of DABCO (50 mmol) in dioxane (50 mL), a solution of benzyl bromide (50 mmol) in dioxane (5 mL) was added slowly for about 20 min. Then, a solution of bromine (50 mmol) in dioxane (20 mL) was cautiously added under vigorous stirring. After cooling the solution, the resulting orange crystals were filtered and dried at r.t.

21

General Procedure for the Oxidative Cyclization of Thiobenzanilides.
To a stirred solution of thiobenzanilide (1 mmol) in CH2Cl2-CCl4 (50:50, 8 mL), OATB (1.1 mmol) was added. The reaction mixture was stirred for 20 min at r.t. and the solvent removed under reduced pressure. The residue was subjected to column chromatography (EtOAc-hexane, 1:5, silica gel) to obtain pure colorless product.
Selected spectroscopic data for compounds 4, 5, 8.
Compound 4: 1H NMR: δ = 8.28 (d, J = 7.3 Hz, 2 H), 8.16 (d, J = 8.2 Hz, 1 H), 7.31 (s, 1 H), 7.15-7.22 (m, 3 H), 7.09 (d, J = 8.2 Hz, 1 H).
Compound 5: 1H NMR: δ = 8.96 (d, J = 7.8 Hz, 1 H), 8.17 (d, J = 7.0 Hz, 2 H), 7.83 (d, J = 7.8 Hz, 1 H), 7.75 (d, J = 8.6 Hz, 1 H), 7.66 (d, J = 8.3 Hz, 1 H), 7.60 (t, J = 7.2 Hz, 1 H), 7.48 (t, J = 7.5 Hz, 1 H), 7.36-7.41 (m, 3 H).
Compound 8: 1H NMR: δ = 8.31 (s, 2 H), 7.21-7.36 (m, 10 H).