Oxidative (3+3) Cycloaddition/Ring-Opening Reactions of Simple Urea Derivatives and N , N '-Cyclic Azomethine Imines to Construct 1,2,3,5-Tetrazine-4(1 H )-one Derivatives.

A novel oxidative (3 + 3) cycloaddition/ring-opening reaction of N , N '-cyclic azomethine imines with the in situ generated diaza-oxylallyl cations from simple urea derivatives in the presence of base and PhI(OAc) 2 has been developed. This transformation performs well over a broad substrate scope, which provides facile and rapid access to 1,2,3,5-tetrazine-4(1 H )-one derivatives in good yields.