[3+2] Cycloaddition of N-Aminopyridines and Perfluoroalkynylphosphonates: Facile Synthesis of Perfluoroalkylated Pyrazolo[1,5-a]pyridines Containing a Phosphonate Moiety

Abstract

1,3-Zwitterions generated from N-aminopyridines in the presence of base are trapped by perfluoroalkynylphosphonates to yield a variety of perfluoroalkylated pyrazolo[1,5-a]pyridine derivatives bearing a phosphonate group. The salient features of these [3+2] cycloadditions include operational simplicity, good tolerance of functional groups, and good to excellent yields at room temperature.