Merrifield resin-supported quinone as the Efficient Biomimetic Catalyst for Metal-Free, Base-Free, Chemoselective Synthesis of 2,4,6-Trisubstituted Pyridines

Metal-free, base-free, biomimetic and chemoselective synthesis of 2,4,6-trisubstituted pyridines was developed under mild conditions for the first time. The heterogeneous biomimetic catalyst – recoverable Merrifield resin-supported quinone, was fully characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometry (XPS) and energy dispersive X-ray spectroscopy (EDX). This supported quinones catalyst exhibited excellent catalytic reactivity for chemoselective synthesis of 2,4,6-trisubstituted pyridines, providing an efficient and green method for the synthesis ofthe pyridine derivatives under mild conditions. Mechanistic investigations were conducted to gain insight into the heterogeneous biomimetic catalyst as well as the resulting transformation. Successful capture of intermediates offered a direct and clear evidence for the proposed mechanism.