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 circle 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 Bronsted 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 circle C. A direct synthesis of A(4)-tetraphenylporphyrin from excess pyrrole and phenylglyoxylic acid in the presence of K2S2O8 at 90 circle C is also reported.

Automated summary

The study reports a method for synthesizing dipyrromethanes at 90°C in the presence of K(2)S(2)O(8) with high yields. The method avoids the use of excess pyrrole, using instead a stoichiometric amount, and demonstrates potential for scale-up production of dipyrromethanes.