[3 + 2]-Cycloaddition of Azaoxyallyl Cations with Hexahydro-1,3,5-triazines: Access to 4-Imidazolidinones.

A novel base-promoted [3 + 2] cycloaddition reaction of azaoxyallyl cations with hexahydro-1,3,5-triazines has been developed, affording 4-imidazolidinones in moderate to good yields under mild reaction conditions. This simple but efficient protocol features cycloaddition of two in situ formed reactive species in the absence of a transition-metal catalyst.