Simple and catalyst-free synthesis of meso-O-, -S-, and -C-substituted porphyrins

A simple and efficient method for the meso-functionalization of porphyrin has been developed. Kinetic studies of meso-fluoro-, -chloro-, -bromo-, -iodo-, and -nitro-substituted porphyrins (Ni) with phenol reveal that the reaction undergoes a typical aromatic nucleophilic substitution (SNAr) process. This catalyst-free method can be performed with meso-brominated porphyrins and oxygen-, sulfur-, and carbon-based nucleophiles to achieve a wide variety of meso-substituted porphyrins.