TMSOTf-mediated Kröhnke pyridine synthesis using HMDS as the nitrogen source under microwave irradiation

Abstract

An efficient protocol for the preparation of pyridine skeletons has been successfully developed involving the TMSOTf/HMDS (trifluoromethanesulfonic acid/hexamethyldisilane) system for the intermolecular cyclization of chalcones under MW (microwave) irradiation conditions. This method provides a facile approach to synthesize 2,4,6-triaryl or 3-benzyl-2,4,6-triarylpyridines in good to excellent yields. Interestingly, the 2,6-diazabicyclo[2.2.2]oct-2-ene core was obtained by changing the acid additive to Sn(OTf)₂, and the desired product was also confirmed using X-ray single-crystal diffraction analysis.