Construction of a six-membered fused N-heterocyclic ring via a new 3-component reaction: synthesis of (pyrazolo)pyrimidines/pyridines.

A conceptually new three-component reaction was developed to construct a six-membered fused N-heterocyclic ring affording (pyrazolo)pyrimidines/pyridines as potential inhibitors of PDE4. The reaction is catalyzed by triflic acid in acetic acid in the presence of aerial oxygen. This journal is © The Royal Society of Chemistry 2012