Mesoionic Ring Systems

The focus of this chapter is on the synthetic applications of mesoionic heterocycles in 1,3-dipolar cycloaddition reactions, particularly those involving münchnones, and the newer isomünchnones about which most of the chemistry has been reported. Lesser work is also described involving the mesoionic sydnones, thiomünchnones, thioisomünchnones, and other mesoionic ring systems.