A practical non-cryogenic process for the selective functionalization of bromoaryls

A selective and practical bromine–metal exchange process under non-cryogenic conditions was developed by a simple modification of an existing protocol. By directly adding an alkyl lithium RLi reagent to a solution of a bromoaryl substrate ArBr and an alkylmagnesium reagent RMgX, a lithium triarylmagnesiate Ar3MgLi complex formed that allowed for various types of functionalization and more elaborate cross-coupling reactions. The simplicity and improved safety of the method represent a significant improvement over current state of the art that uses lithium trialkylmagnesiate R3MgLi complexes, and is especially advantageous for large-scale synthesis.