Direct catalytic arylation of heteroarenes with -bromophenyl-substituted porphyrins.

The arylation of mono-, di- and tetra--bromophenyl-substituted porphyrins with the heteroarenes containing "acidic" C-H bonds, such as benzoxazole, benzothiazole and -methylimidazole was studied in the presence of three alternative catalytic systems: Pd(dba)/DavePhos/CsCO, Pd(PPh)/PivOH/KCO and Pd(OAc)/Cu(OAc)/PPh/KCO. The first catalytic system was found to be successful in the reaction with benzoxazole, the second one was less efficient for our purpose, while the third system proved to be most versatile and afforded corresponding mono-, di-, tri- and even tetraarylated derivatives of porphyrins.