Catalytic Assessment of Copper(I) Complexes and a Polymer Analog towards the One‐Pot Synthesis of Imines and Quinoxalines

Abstract

Three copper(I) complexes, [CuCl(L)(PPh3)2] [L = FL (1), BL (2) or TL (3)] were prepared from [(PPh3)2Cu(µ‐Cl)2Cu(PPh3)] and N‐carbamothioylfuran‐2‐carboxamide (FL), N‐carbamothioylbenzamide (BL) or N‐carbamothioylthiophene‐2‐carboxamide (TL) ligands in benzene and four‐coordinated tetrahedral copper complexes were well characterized by various spectroscopic techniques (UV/Vis, FT‐IR, 1H NMR, 13C NMR and 31P NMR). The molecular structure of the ligands (FL and BL) and complexes was established from single‐crystal X‐ray diffraction studies. Copper complexes have been shown to catalyse the one‐pot synthesis of imines and quinoxalines. Heterogenized catalyst (4) was prepared by reacting more active complex 3 with polystyrene supported triphenylphosphane, and characterized by elemental analyses, and DRS‐UV, FT‐IR, ICP‐OES, and solid‐state NMR techniques. Catalytic activity of the complexes (3 and 4) was tested in the formation of imines from alcohols and amines, and quinoxalines from hydroxy ketones and diamines. Heterogeneity and reusability of catalyst 4 were evaluated, and the catalyst can be reused for four runs without any loss in activity.