Tetrahydropyrido[3,4-b]pyrazine scaffolds from pentafluoropyridine.

[reaction: see text] Representative polyfunctional tetrahydropyrido[3,4-b]pyrazine scaffolds have been synthesized very readily by a one-pot annelation reaction of pentafluoropyridine with appropriate diamines. The trifluorinated pyridopyrazine products react sequentially with various nucleophiles to give poly-substituted tetrahydropyridopyrazines, demonstrating the potential of the polyfluorinated ring fused pyridine system as a scaffold for the synthesis of previously inaccessible poly-substituted pyridopyrazine derivatives. This general approach has special relevance to the development of new chemical entities for the life science industries and particularly in the drug discovery arena, in which low molecular weight, polyfunctional heterocyclic derivatives are playing an increasingly important role.