“…[8] Very recently, our group disclosed an oxidative cycloaddition/ringopening reaction of N,N'-cyclic azomethine imines with simple urea derivatives for the synthesis of 1,2,3,5-tetrazine-4(1H)-one derivatives. [9] On the other hand, the azaoxyallyl cations which can be generally in situ generated from α-halohydroxamates in the presence of bases were also used as versatile surrogates of "1,3dipole", [10] and a series of [3 + 1], [11] [3 + 2], [12] [3 + 3], [13] [3 + 4] [14] cycloaddition reactions involving azaoxyallyl cations have been developed, in these reactions, sulfur ylides was employed as one-atom synthons, 2π systems and 4π systems were employed as two-atom and four-atom units respectively. Especially, other 1,3-dipoles such as isoquinoline N-oxides and nitrones were successfully explored as three atom cycloadditon partners with azaoxyallyl cations in the [3 + 3] cycloadditions by several groups.…”