Applications of Purine Ring Opening in the Synthesis of Imidazole, Pyrimidine, and New Purine Derivatives

Abstract Purines, which are regarded as relatively stable heterocyclic systems, can be opened at both pyrimidine and imidazole rings. Purine ring opening also serves as a tool for the preparation of ring‐modified purines through rearrangement/recyclization mechanisms. The obtained imidazole, pyrimidine, and purine derivatives are privileged molecular scaffolds in medicinal and agricultural chemistry. Purine ring‐opening approach is a useful alternative for their synthesis, which competes well with de novo approach or modification of a conserved heterocyclic core. The substitution patterns and groups that activate purines towards ring opening are reviewed. Moreover, mechanistic studies using labelled substrates, which are leading to rearranged purine derivatives are covered. Furthermore, an insight into imidazole ring opening upon exposure of purine system to DNA damaging agents is provided.