Intensification of Pd-catalyzed Suzuki Cross-coupling: Influence of Second Metal Addition, Reactor Type and Visible Light Irradiation

Abstract

This work is devoted to the synthesis of Pd- and Au-containing mono- and bimetallic 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 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/water mixture as a solvent and NaOH as a base. The highest catalytic activity was observed for Au-Pd/HPS catalyst containing 1.15 wt.% of Pd and 1.80 wt.% of Au andreduced with aqueous solution of NaBH4 (more than 98 %of 4-BrAn conversion was achievedfor 3 h of reaction time). Selectivity was higher than 98 % with respect to 4-methoxybiphenyl (4-MBP). Thus HPS-supported bimetallic palladium catalysts were found to be promising (active, selective) and simple in preparation for the Suzuki cross-coupling at mild temperatures along with the absence of the necessity to use phase-transfer agents.