(135a) Aqueous Reaction and Processing in Suzuki-Miyaura Couplings Using Immobilized Palladium Catalysts in a Phosphine-Free System

A holistic process approach to the Suzuki-Miyaura coupling is reported using an essentially water based system containing only 3% toluene in the initial reaction mixture.  The base was chosen to be soluble in water and the temperature was maintained at 90 °C under stirred batch conditions.

A reactive crystallization process occurs where the product precipitated as a fine white powder.  By tuning the ratio of boronic acid to organobromide we were able to drive the reaction to 100% yield of product with 100% selectivity.  The solid phase catalyst was filtered off using a coarse mesh and washed with 0.1M aqueous sodium hydroxide followed by water.  The fine crystalline product was recovered by filtration through a porous frit.  Analysis of the product showed it to be free from contamination.  Excess reagents were then recycled back into the reaction.  Results using a diverse range of boronic acids and organobromides will be reported.