In situ produced palladium nanoparticle-catalyzed efficient synthesis of benzo[c]chromenes and analogues under aerobic and ligand-free conditions in water

Abstract

An efficient approach has been discovered towards the preparation of 6H-benzo[c]chromenes and analogues via the in situ developed palladium nanoparticle-catalyzed cascade of Suzuki-Miyaura cross-coupling and intramolecular S_N2 reaction under aerobic conditions. To make the reactions eco-friendly, water was chosen as the solvent along with the use of phosphine ligand was avoided. The reactions were found to be highly efficient with the productions of the chromenes upto the excellent yield of 96 % at 80 °C. Therefore, the several advantages like eco-friendly, mild, easy to handle, tolerance of various functional groups and efficient production of diverse benzo[c]chromenes have made this method as novel.