Diversity-Oriented Synthesis toward Aryl- and Phosphoryl-Functionalized Imidazo[1,2- a]pyridines

J Org Chem. 2020 Nov 20;85(22):14730-14743. doi: 10.1021/acs.joc.0c02059. Epub 2020 Nov 9.

Abstract

We report herein an efficient synthesis of diversely polysubstituted imidazo[1,2-a]pyridines, a family of aza-heterocycles endowed with numerous biological properties, through a sequence involving two consecutive palladium-catalyzed cross-coupling reactions. First, we demonstrated that a Hirao coupling occurred straightforwardly in high yields at positions 3, 5, and 6 of imidazopyridine derivatives, giving access to a wide variety of substituted phosphonates, phosphinates, and phosphine oxides. In a second step, direct CH-arylation of phosphorylimidazopyridines with aryl halides was found to be effective and fully selective, leading to 3-aryl-substituted imidazopyridines in moderate to high yields depending on steric hindrance.

Publication types

  • Research Support, Non-U.S. Gov't