Rational Synthesis of Tripyrranes

The rational, chromatography-free synthesis of two regioisomeric 5,10-diaryltripyrranes from pyrrole and aromatic acids has been developed. The strategy is general and should be applicable to a broad range of acids. This methodology was successfully applied to the synthesis of monoprotected dipyrrane. The oxidation of N,N′-bis-mesyltripyrrane under basic conditions led to the formation of both known tripyrrin-1-one and unknown 1-methoxytripyrrina fluorescent dye strongly absorbing green light.