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
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
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
4 He Y.
Benz A.
Fu T.
Wang M.
Covey DF.
Zorumski CF.
Mennerick S.
Neuropharmacology
2002,
42:
199
5 Bensimon G.
Lacomblez L.
Meininger V.
New Engl. J. Med.
1994,
330:
585
6 Foscolos G.
Tsatsas G.
Champagnac A.
Pommier M.
Ann. Pharm. Fr.
1977,
35:
295
7 Shirke VG.
Bobade AS.
Bhamaria RP.
Khadse BG.
Sengupta SR.
Indian Drugs
1990,
27:
350
8 Paget CJ.
Kisner K.
Stone RL.
Delong DC.
J. Med. Chem.
1969,
12:
1016
9 Gong B.
Hong F.
Kohm C.
Bonham L.
Klein P.
Bioorg. Med. Chem. Lett.
2004,
14:
1455
10 Hutchinson I.
Bradshaw TD.
Matthews CS.
Stevens MFG.
Westwell AD.
Bioorg. Med. Chem. Lett.
2003,
13:
471
11 Ivanov SK.
Yuritsyn VS.
Neftekhimiya
1971,
11:
99 ; Chem. Abstr. 1971 , 74 , 124487m
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
14 Ranu BC.
Jana R.
Dey SS.
Chem. Lett.
2004,
33:
274
15a Schwartz H. inventors; Neth. Appl. 6,607,039.
15b Osuka A.
Uno Y.
Horiuchi H.
Suzuki H.
Synthesis
1984,
145
15c Saikachi H.
Hisano T.
Chem. Pharm. Bull.
1960,
8:
51
15d Saikachi H.
Hisano T.
Chem. Pharm. Bull.
1959,
7:
716
16a Hugerschoff H.
Chem. Ber.
1901,
34:
3130
16b Hugerschoff H.
Chem. Ber.
1903,
36:
3121
17 Sprague JM.
Land AH. In
Heterocyclic Compounds
Vol. 5:
Eldrenfield RC.
J. Wiley;
New York:
1958.
Chap. 8.
p.484-721
18 Jordan AD.
Luo C.
Reitz AB.
J. Org. Chem.
2003,
68:
8693
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.
20 Matloubi Moghaddam F.
Zali Boeini H.
Taheri S.
J. Sulfur Chem.
2004,
25:
407
21
General Procedure for the Oxidative Cyclization of Thiobenzanilides.
2 Cl2 -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.4 , 5 , 8 .4 : 1 H 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).5 : 1 H 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).8 : 1 H NMR: δ = 8.31 (s, 2 H), 7.21-7.36 (m, 10 H).
