K2S2O8 mediated synthesis of 5-aryldipyrromethanes and meso-substituted A4-tetraarylporphyrins

The synthesis of dipyrromethanes from pyrrole and arylglyoxylic acids in the presence of K 2 S 2 O 8 at 90 [Formula: see text]C is reported affording dipyrromethanes in very good yields. Unlike an excess pyrrole traditionally used in dipyrromethane synthesis, the current method uses a stoichiometric amount of pyrrole avoiding any use of Brønsted or Lewis acid. A gram scale synthesis of 5-phenyldipyrromethane is also achieved demonstrating potential scale up of dipyrromethanes using this method feasible. Subsequently, dipyrromethanes were converted to A 4 -tetraarylporphyrins also in the presence of K 2 S 2 O 8 at 90[Formula: see text]C. A direct synthesis of A 4 -tetraphenylporphyrin from excess pyrrole and phenylglyoxylic acid in the presence of K 2 S 2 O 8 at 90[Formula: see text]C is also reported.