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Synlett 2010(16): 2457-2460  
DOI: 10.1055/s-0030-1258046
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

One-Pot Tandem Approach for the Synthesis of Benzothiazoles from Benzyl Halides

Chen Zhu, Takahiko Akiyama*
Department of Chemistry, Gakushuin University, 1-5-1, Mejiro, Toshima-ku, Tokyo 171-8588, Japan
Fax: +81(3)59921029; e-Mail: takahiko.akiyama@gakushuin.ac.jp;
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Publikationsverlauf

Received 23 June 2010
Publikationsdatum:
19. August 2010 (online)

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Abstract

A one-pot tandem approach for the synthesis of benzothiazoles from benzyl halides and o-aminobenzenethiol was described. Benzothiazoles were obtained in high chemical yields under mild conditions in DMSO in the absence of an additional oxidant. Both benzyl chlorides and bromides bearing a range of substituents proved to be suitable substrates.

Key words

benzothiazole - benzyl halide - oxidation - one-pot - tandem reaction

13

Treatment of benzaldehyde with o-aminothiophenol under the same reaction conditions gave the corresponding benzothiazole in 80% yield.

14

o-Aminophenol was not a suitable substrate and the corresponding benzoxazole was furnished in low yield under the same conditions.

15

General Experimental Procedure A mixture of benzyl halide (0.24 mmol, 1.2 equiv) with NaHCO3 (1 mmol, 5.0 equiv) in DMSO (2 mL) was stirred for 5 h at 90 ˚C. Then, o-aminothiophenol (0.2 mmol, 1.0 equiv) was added into the above solution. Resulting solution was continued stirring for overnight up to the completion of the reaction. The reaction mixture was cooled to r.t. and was extracted with EtOAc. The combined organic layers were successively washed with H2O and brine, dried over anhyd Na2SO4, and concentrated to dryness. The crude product was purified by preparative TLC on silica gel to give the product.