Ligand-Controlled C2- or C3-Selectivity Switching in the Palladium-Catalyzed C-H Arylation of Nonsubstituted 1H-Pyrrole.

The C2- or C3-selective direct C-H arylation of nonsubstituted 1H-pyrrole with aryl chlorides/nonaflates was achieved using catalysts derived from palladium and appropriate phosphine ligands. The site selectivity of the arylation can be switched by changing the ligands, and the C3-selective arylation of nonsubstituted 1H-pyrrole was realized for the first time. tBuOLi played an important role in suppressing N-arylation and accelerating C2- or C3-arylation.