Combinatorial Synthesis of 5-Aryl-[1,2,4]-triazolo-[1,5-a]-pyridine Derivatives as Potential Inhibitors of the Adenosine 2A Receptor

All articles of this category A novel and efficient 4-step synthesis of 2,4-diamino-4-bromo-pyridine 4 in 56% overall yield by a double Curtius rearrangement as a key step is reported. N -amination of 2,4-diamino-4-bromo-pyridine 4 with O -mesitylenesulfonylhydroxylamine 10 and subsequent reaction with aldehydes yielded, upon oxidative ring-closure, 5-bromo-triazolopyridines 2a-2f . Thereafter, from a combinatorial parallel Suzuki cross-coupling reaction 260 previously non-described 5-aryl-[1,2,4]-triazolo-[1,5-a]-pyridines 1 were obtained in acceptable overall yield. Adenosine 2A - double-Curtius rearrangement - N -amination - Suzuki cross-coupling reaction - 7-amino-triazolopyridine derivatives