Synthesis of β-Functionalized Porphyrins via Palladium-Catalyzed Carbon−Heteroatom Bond Formations: Expedient Entry into β-Chiral Porphyrins

A procedure was developed for the preparation of β-monobromo-tetraphenylporphyrin (BrTPP) in a greatly improved yield from the selective bromination of tetraphenylporphyrin (TPP) by NBS. BrTPP was successfully employed as a versatile synthon for convenient synthesis of a wide range of β-monofunctionalized porphyrins with various heteroatom functionalities via palladium-mediated carbon−heteroatom bond formations. Examples include β-amino, -amido, -oxo, and -mercaptoporphyrins from reactions with amines, amides, alcohols, and thiols, respectively. Applying the synthetic approach to chiral amides, β-chiral porphyrins were effectively constructed.