Transition metal-catalyzed C–N cross-coupling reaction of bromine-substituted pyranilidene derivatives: synthesis, characterization, and optical properties study of pyran-based chromophores

Abstract

In this work, the C–N cross-coupling reaction between bromine-substituted pyranilidene derivatives, and a variety of secondary amines was studied in the presence of transition metal catalysts. The CuI/l-proline, Pd(OAC)2/PPh3, and MnCl2.6H2O/l-proline were chosen as catalyst/ligand systems. The copper-catalyzed Ullmann amination reaction in the presence of l-proline as auxiliary ligand shows the best yield. The structure of pyran-based chromophores was confirmed using FT-IR, 1H NMR, 13C NMR, and mass spectroscopy. Additionally, the linear optical properties of final compounds were investigated using UV–Vis and fluorescent spectroscopy. The large stokes shifts for final compounds show the capability of using these compounds in optical applications.