A PRACTICAL SYNTHESIS OF 2-SUBSTITUTED 5-BROMOINDOLES

摘要

This paper describes a non-cryogenic synthetic procedure for a variety of 2-substituted 5-bromoindoles. The direct magnesiation of 5-bromo-1-(4-toluenesulfonyl)indole with a mixture of i-PrMgCl/LiCl and diisopropylamine allows for the preparation of various 2-substituted indoles. The advantages of this procedure include the non-cryogenic conditions, simple operations and inexpensive Grignard reagents. In addition, this procedure is especially advantageous for the preparation of 2,5-dibromoindole with reduced synthetic steps, low production cost and good overall yields.