Suzuki Cross-coupling in Environmentally Friendly Solvents in a Batch Mode Using Hypercrosslinked Polystyrene-supported Pd Catalysts

Abstract

This work is devoted to the synthesis of Pd-containing catalysts based on hypercrosslinked polystyrene (HPS) and study of their catalytic properties in Suzuki cross-coupling of 4-bromoanisole (4-BrAn) and phenylboronic acid (PBA). Series of Pd-containing HPS-based catalysts were synthesized at variation of Pd content and tested in Suzuki cross-coupling of 4-BrAn and PBA in a batch mode at ambient pressure while using ethanol (EtOH) and EtOH/water mixtures as solvents. The highest catalytic activity was observed at EtOH/water ratio of 5 : 1 while using NaOH as a base (the conversion of 4-BrAn has reached higher than 98% for less than 1 h of reaction time). Selectivity was higher than 95 % with respect to 4-methoxybiphenyl. Thus HPS-supported palladium catalysts were found to be promising (active, selective), simple in preparation and stable for at least three consecutive runs for the Suzuki cross-coupling at mild temperatures along with the absence of the necessity to use phase transfer agents.