Acidic tributyl phosphonium-based ionic liquid: an efficient catalyst for preparation of diverse pyridine systems via a cooperative vinylogous anomeric-based oxidation

Abstract

In this study, an acidic phosphonium-based ionic liquid, namely tributyl(3-sulfopropyl)phosphonium trifluoroacetate, was designed and synthesized via a facile and green route. From an accurate perspective, the structure of the prepared ionic liquid was investigated using FT-IR, ¹H NMR and ¹³C NMR spectroscopies, and EDX, elemental mapping and TGA/DTG analysis. In this intensive research, catalytic application of tributyl(3-sulfopropyl)phosphonium trifluoroacetate was explored for the preparation of diverse pyridine systems such as triaryl pyridines, 2-amino-3-cyanopyridines and indolyl pyridines via a cooperative vinylogous anomeric-based oxidation (CVABO). The observed results proved that prepared acidic phosphonium-based ionic liquid is a effective catalyst for the multicomponent synthesis of pyridines.