Traditional Grignard reagents are made by reacting alkyl halide with Magnesium metal. However, the preparation and scope of their application have been limited because of low functional group tolerance.
Until recently, Knochel and coworkers have demonstrated the functional-group tolerance of magnesium-halogen exchange, which is now the method of choice for the preparation of highly functionalized organomagnesium reagents at low temperature as shown in the example
Turbo Grignard reagent ( isopropyl magnesium chloride) is used to change iodine or bromine with Magnesium.
what is reaction mechanism for exchange between iodine and magnesium?