Synthesis of Amidoalkyl Naphthols in PEG-400 as a Green and Efficient Solvent and Theoretical Study of their Spectroscopic Properties

An efficient synthesis of amidoalkyl naphthols from the multicomponent reaction of 2 naphthol, aromatic aldehydes, and benzamide derivatives using PEG-400 as an environmentally friendly solvent is described. The main advantage of this protocol is that the benzamide derivatives with low reactivity, such as 4-nitro benzamide, can react effectively. Also, the molecular structure, IR, and C-13 NMR spectra of the synthesized compounds are also investigated theoretically. Density functional theory (DFT) calculations at the B3LYP level of theory are carried out to locate optimized geometries and calculate vibrational normal modes and C-13 NMR chemical shifts. These calculations enable us to assign the observed FT-IR and C-13 NMR peaks to the corresponding vibrational motions and C-13 atoms, respectively.