Mixed Mg/Li Amides of the Type R_2NMgCl centre dot LiCI as Highly Efficient Bases for the Regioselective Generation of Functionalized Aryl and Heteroaryl Magnesium Compounds

摘要

The metalation of arenes is one of the most useful transformations in organic synthesis since it allows the regioselec-tive functionalization of various aryl and heteroaryl derivatives.Traditionally,strong bases such as alkyl lithium reagents (RLi) and lithium amides (R_2NLi) have been used for such deprotonations.However,these bases often lead to undesirable side reactions as a result of their high reactivity and their strong nucleophilicity (e.g.Chichibabin addition).Another serious limitation is the low stability of lithium amides in THF solutions at room temperature,which requires in situ generation of these reagents.