Multicomponent Aromatic and Benzylic Mannich Reactions through C−H Bond Activation

Abstract Multicomponent Mannich reactions through C−H bond activation are described. These transformations allowed for the straightforward generation of densely substituted benzylic and homo‐benzylic amines in good yields. The reaction involves a reaction between two transient species: an organometallic species, generated by transition‐metal‐catalyzed sp 2 or sp 3 C−H bond activation and an in situ generated imine. The use of an acetal as an aldehyde surrogate was found essential for the reaction to proceed. The process could be successfully applied to Rh III ‐catalyzed sp 2 C−H bond functionalization and extended to Cu II ‐catalyzed sp 3 C−H bond functionalization.