Imine complexes insertion into metal hydrides

Proposed mechanism for the Pd/C-catalyzed oxidative synthesis of 2-substituted benzimidazoles was depicted in Scheme 14.11. The initial step seems to be the insertion of palladium into a C-H adjacent to the nitrogen, leading to a highly active intermediate complex of an iminium ion. The proposed catalytic cycle involves the removal of a hydride from tertiary amine by a metal catalyst to form (putative) oxidized iminium cation species, which undergoes a transamination reaction with o-phenylenediamine to generate intermediate imine, with generation of Imol equivalent of H2. Subsequent formation of... 

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