Hyperbranched Polysiloxane-Copper(II) Pyridylamine-Glycidoxypropyltrimethoxysilane Complex-Catalyzed Click Reactions under Mild Conditions

Herein, we present the synthesis of a novel heterogeneous, supported copper catalyst. This catalyst was prepared via a one-pot process involving simultaneous polymerization and ring-opening reactions occurring at different ends of a 3-glycidoxypropyltrimethoxysilane chain, in conjunction with 2-Pyridylamine without using heterogeneous supports. This reaction generated a pyridylamine-functionalized hyperbranched polysiloxane, which served as a heterogeneous ligand for subsequent complexation with copper ions, resulting in the formation of the [Cu-(II)-2PA-GPTMS-HBPSi] complex. The framework of this complex is characterized by a highly branched structure composed of silicon and oxygen atoms, interconnected by 2-Pyridylamine ligand building blocks, and exhibits remarkable regularity. The evaluated complex demonstrated excellent catalytic activity in the click synthesis of 5-substituted 1H-tetrazoles, serving as a model reaction and yielding the desired heterocycles in excellent yields and within short reaction times. Reusability, hot filtration, and leaching tests underscore its excellent reversibility, cyclability, structural stability, and specific capacity of up to five cycles. Consequently, this innovative method has emerged as a convenient and efficient alternative for the synthesis of heterogeneous catalysts and materials.