[reaction: see text] A convergent synthesis of substituted pyrazolo[1,5-a]pyridines has been achieved either via a regioselective [3 + 2] cycloaddition of N-aminopyridines with alkynes or by thermal cyclization of disubstituted azirines. Subsequent palladium-catalyzed introduction of pyridines or de novo synthesis of pyrimidines affords inhibitors of p38 kinase.
GlaxoSmithKline, Research and Development, Department of Medicinal Chemistry, 5 Moore Drive, Research Triangle Park, North Carolina 27709, USA. Kirk.L.Stevens@gsk.com
