POPd/TBAB co-catalyzed Suzuki cross-coupling reaction of heteroaryl chlorides/bromides with 4-fluorophenylboronic acid in water

An organic solvent free and efficient heterogeneous synthesis for bridging heteroaryl halides and 4-fluorophenylboronic acid was studied in aqueous media according to the Suzuki cross-coupling protocol. High yields of heteroaryl-aryl fluorides were successfully obtained with: chloro-/bromo-substituted pyridine, thiophene, indole, and inzole in neat water using palladium phosphinous acid complexes (POPd)/tetrabutylammonium bromide (TBAB) as co-catalysts. A possible mechanism for the heterogeneous coupling reaction is proposed and discussed according to the function of the TBAB interphases. The notable properties of the reported method are highly co-catalytic activity, hetero-atom tolerance, simple separating procedure and little environmental disposal impact.