Glucoconjugated Dinuclear Copper(II) Complex: An Efficient Catalyst for Stereoselective Synthesis of Trisubstituted Propargylamines via Solvent-free A Coupling Reaction.

Development of catalytic systems using nontoxic natural precursors is the need of the era, and along this line, we have synthesized a new D-glucose derived ligand (4,6-O-ethylidene-N-(2-hydroxy-4-(octyloxy)benzylidene)-β-D-glucopyranosylamine) and its dinuclear copper(II) complex. The molecular structure of the complex has been established by single-crystal X-ray diffraction studies and detailed noncovalent intermolecular interactions present in it have been explored by Hirshfeld surface analysis. Further, the complex has been used as a catalyst in the enantioselective (87-99 % ee) synthesis of propargylamines in good to excellent yield (82-95 %) via aldehyde-amines-alkynes (A) coupling reaction under solvent-free condition. The formation of aminal intermediate during the reaction has been confirmed by H-NMR and single-crystal X-ray diffraction studies. The catalytic system is reusable without any appreciable loss in the enantioselectivity or product yield.