Diverse Functionalization of Ruthenium-Chelated 2-Picolylamines: Oxygenation, Dehydrogenation, Cyclization, and N-Dealkylation.

"Chemical noninnocence" of metal-coordinated 2-picolylamine (PA) derivatives has been introduced upon its reaction with the metal precursor [RuII(Cl)(H)(CO)(PPh3)3] under basic conditions. This in effect leads to the facile formation of metalated amide, imine, ring-cyclized pyrrole, and an N-dealkylated congener based on the fine-tuning of an amine nitrogen (Namine) and a methylene center (Cα) at the PA backbone. It develops oxygenated L1' in 1 and cyclized L4' in 4 upon switching of the Namine substituent of PA from aryl to an electrophilic pent-3-en-2-one moiety. On the other hand, imposing the substituent at the Cα position of PA modifies its reactivity profile, leading to a dehydrogenation (2/3) or N-dealkylation (6) process. The divergent reactivity profile of metalated PA is considered to proceed through a common dianionic intermediate. Further, a competitive scenario of C-H bond functionalization of coordinated PA versus the ligand-exchange process has been exemplified in the presence of external electrophile such as benzyl bromide or methylene iodide. Authentication of the product formation as well as elucidation of the reaction pathway has been addressed by their crystal structures and spectroscopic features in conjunction with the transition-state (TS) theory.