Synthesis of polycyclic aminal heterocycles via decarboxylative cyclisation of dipeptide derivatives

An oxidative-decarboxylative intramolecular cyclisation of dipeptide derivatives is reported. This transformation is promoted by phenyl iodine(iii) diacetate (PIDA) in combination with BF3 center dot OEt2. The reaction gives access to a variety of valuable polycyclic N-heterocyclic scaffolds containing 5-, 6-, or 7-membered rings.