Transition-Metal-Free [3+2] Cycloaddition of Dehydroaminophosphonates and N-Tosylhydrazones: Access to Aminocyclopropanephosphonates with Adjacent Quaternary-Tetrasubstituted Carbon Centers.

A novel one-step strategy for the synthesis of aminocyclopropanephosphonates containing adjacent quaternary-tetrasubstituted carbon centers under transition-metal-free catalysis via [3+2] cycloaddition process has been developed. A series of aminocyclopropanephosphonates with adjacent quaternary-tetrasubstituted carbon centers including spirocyclopropyl adducts were obtained in moderate to excellent yields under mild reaction conditions. This protocol would find the potential applications in biochemistry and medicinal chemistry.