Electrochemical [3+3] Annulation of Phenol and Hydrazone: Synthesis of 1,3,4-Oxadiazines

A novel [3+3] cyclization reaction between phenol and hydrazone was successfully developed under electrochemically driven conditions. This reaction provided access to a diverse array of 1,3,4-oxadiazinane compounds in consistently high yields, reaching up to 87%. Notably, the reaction exhibited remarkable tolerance toward a broad spectrum of both phenol and hydrazone substrates, underscoring its versatility. Moreover, the protocol distinguished itself by its exceptional atom and step economy, facilitating the efficient construction of functionalized 1,3,4-oxadiazines. The synthetic utility of this approach was further exemplified by its scalability, as demonstrated by gram-scale reactions, and its broad substrate scope.