Synthesis and DFT Study of 7-Bromophenylnaphthopyran Moieties

Abstract

A one-pot, three-component reaction of 6-bromo-2-naphthol (1), p-chlorobenzaldehyde (2) and malononitrile or ethyl cyanoacetate (3) in ethanol/piperidine under reflux was performed to afford 4H-naphtho[2,1-b]pyrano-3-carbonitrile (4a) and ethyl 4H-naphtho[2,1-b]pyrano-3-carboxylate (4b) derivatives, respectively. The structure of these compounds was determined using IR, 1H NMR, 13C NMR, mass spectroscopy and UV-Vis spectra. The molecular geometry of compounds 4a and 4b was determined at the B3LYP/631+G(d) level. The geometric optimization was performed on two tautomers and two conformers. Tautomers were separated by about 7.942 kcal/mol, while rotational conformers were separated by just 0.511 kcal/mol. The global electrophilicity, hardness, softness and local condensed Fukui functions were calculated and considered as molecular reactivity descriptors, moreover the frontier molecular orbitals (HOMO and LUMO) were also calculated.