Alkoxide-Directed Iodine-Magnesium Exchange at sp3 Centers

Abstract

The halogen-magnesium exchange is a well-established method for the preparation of sp2-hybridized Grignard reagents. The synthesis of sp3-hybridized Grignard reagents via halogen-magnesium exchange processes, however, is difficult and only comparatively few examples have been reported so far. In this article, a novel synthetic approach is presented in which iodine-magnesium exchange on sp3-carbon centers is achieved by the intramolecular directing effect of neighboring alkoxide groups. The exchange can thus proceed rapidly at -78 °C giving access to novel cyclic Grignard reagents.