Synthesis of 2-aryl-4H-pyrano[2,3-b]pyridin-4-ones by a one-pot deprotection–cyclization reaction

An efficient synthesis of 2-aryl-4H-pyrano[2,3-b]pyridine-4-ones is reported, using a one-pot, two step process in the presence of pyridinium hydrochloride. The methodology is compatible with a series of functional groups useful for the synthesis of second generation analogs, as part of our SAR program. In addition, the method proved to be scalable (>100 g), allowing for efficient synthesis of material to support animal studies.