Polyfunctional tetrahydropyrido[2,3-b]pyrazine scaffolds from 4-phenylsulfonyl tetrafluoropyridine.

[Reaction: see text]. Polyfunctional tetrahydropyrido[2,3-b]pyrazine scaffolds can be synthesized by sequential reaction of pentafluoropyridine with sodium phenylsulfinate and an appropriate diamine. The polyfunctionality possessed by the difluorinated tetrahydropyrido[2,3-b]pyrazine scaffolds was demonstrated in selected model reactions with nucleophiles to give access to various polysubstituted [6,6]-ring fused systems.