Associative Covalent Relay: An Oxadiazolone Strategy for Rhodium(III)-Catalyzed Synthesis of Primary Pyridinylamines.

A relay formalism is proposed herein for categorizing the interplay among reactants, target product, and catalytic center in transition-metal catalysis, an important factor that can dictate overall catalysis viability and efficiency. In this formalism, transition-metal catalysis can proceed by dissociative relay, associative covalent relay, and associative dative relay modes. An intriguing associative covalent relay process operates in rhodium(III)-catalyzed oxadiazolone-directed alkenyl C-H coupling with alkynes and allows efficient access to primary pyridinylamines. Although the primary pyridinylamine synthesis mechanism is posteriori rationalized, the relay formalism formulated herein can provide an important mechanistic conceptual framework for future catalyst design and reaction development.