Dearomatization Strategy for the Synthesis of Arylated 2H-Pyrroles and 2,3,5-Trisubstituted 1H-Pyrroles

The first high-yielding route to arylated 2H-pyrroles was developed. The methodology utilizes 2,5-disubstituted pyrroles that are metalated, and the aryl substituents are introduced by a palladium-catalyzed cross coupling reaction. The prepared pyrroles can be rearranged to 2,3,5-trisubstituted pyrroles under acidic conditions. Attempts to convert the 2,3,5-trisubstituted pyrroles to 2,3,4,5-tetrasubstituted pyrroles by the dearomatization rearrangement strategy were unsuccessful.