Minimization of Side Reactions in Bromine Magnesium Exchanges with <i>i-</i>PrMgCl/LiCl and <i>s-</i>BuMgCl/LiCl Mixtures

Abstract

The efficiency of halogen−magnesium exchange reactions can dramatically be increased by the addition of LiCl. However, also the organic substituents at the magnesium center of the Grignard reagent play an important role. In a competitive reaction gaseous side products are formed. In the presence of LiCl this interfering reaction is suppressed. Thus, carrying out bromine−magnesium exchanges with RMgCl/LiCl TurboGrignard solutions instead of RMgCl gives better results (R = i-Pr, s-Bu). The application either of i-PrMgCl/LiCl or of s-BuMgCl/LiCl in halogen−magnesium exchange reactions results in higher conversions and also in less gaseous side products, facts that should be considered for scale-up processes.