Ruthenium(II)-Catalyzed [4 + 2] Electro-Oxidative Annulation of <i>C</i><sup>6</sup>-Arylpurines/Purine Nucleosides
Qi‐Liang Yang, Yi-Rui Luo, Rong-Yi Xu, Beining Zhang, Yanni Zhang, Hai‐Ming Guo
Abstract
A sustainable pathway for the synthesis of tetracyclic purinium salts via ruthenium-catalyzed electro-oxidative annulation of C 6 -arylpurine nucleosides with alkynes without a stoichiometric metal oxidant has been developed. The protocol described herein exhibits high regioselectivity, broad scope, and wide functional group tolerance, allowing efficient coupling of various biologically important molecules including acyclic, ribosyl, arabinosyl, and deoxyribosyl purine nucleoside derivatives. A novel purinoisoquinolinium-coordinated ruthenium(0) sandwich intermediate has been isolated, crystallographically characterized, and electrochemically analyzed, offering direct mechanistic insight.