Catalytic amination of 2-substituted pyridines with hydrazine derivatives

[GRAPHICS] Protected pyridylhydrazine derivatives were prepared in a one-step palladium-catalyzed amination reaction using chelating phosphine ligands, 2-Pyridyl chlorides, bromides, and triflates were effective electrophiles in these reactions, Di-tert-butyl hydrazodiformate was an excellent hydrazine substrate, and the resulting products were deprotected under mild conditions. Catalytic amination provides a direct route to protected bifunctional hydrazinopyridine linkers that are suitable for metal-bioconjugate syntheses.