Synthesis 2007(10): 1535-1541  
DOI: 10.1055/s-2007-966030
PAPER
© Georg Thieme Verlag Stuttgart · New York

Halogenation of Indoles with Copper(II) Halides: Selective Synthesis of 2-Halo-, 3-Halo-, and 2,3-Dibromoindoles

Shi Tanga,b, Jin-Heng Li*b, Ye-Xiang Xieb, Nai-Xing Wang*a
a Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100101, P. R. of China
b Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, P. R. of China
Fax: +86(731)8872531; e-Mail: jhli@hunnu.edu.cn;
Further Information

Publication History

Received 30 January 2007
Publication Date:
02 May 2007 (online)

Abstract

A simple and selective protocol for the halogenation of indoles with copper(II) bromide or chloride to synthesize 2-halo-, 3-halo-, and 2,3-dibromoindoles was developed. It was found that both base and water could be used as switches for the selectivity of the halogenation reactions. In the presence of copper(II) halide and sodium hydroxide, 3-haloindoles were obtained as the major products, whereas the selectivity was shifted toward 2,3-dihaloindoles when water was added instead of sodium hydroxide. Moreover, 2-halogenations of 3-substituted indoles were also performed successfully in moderate to good yields under the standard conditions.