Pyrazolo[1,5-a]pyridines as p38 kinase inhibitors

reaction: see text] A convergent synthesis of substituted pyrazolo1,5-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.