Soluble polymer supports for homogeneous catalysis in flow reactions

Abstract

The use of polyisobutylene and poly(4-dodecylstyrene) bound catalysts that contain transition metal or organocatalysts for cyclopropanation, ring-closing metathesis, and nucleophilic catalysis in flow chemistry schemes is described and compared with similar catalysts used in batch reactions. These Rh(II) carboxylate catalysts, N-heterocyclic carbene-ligated Ru(II) benzylidene catalysts, and analogs of 4-dimethylaminopyridine catalysts were used in reactions in heptane in flow and then separated in a gravity based liquid/liquid separation using a biphasic heptane/acetonitrile mixture. The less dense catalyst-containing phase in that separation was continuously used in flow with fresh substrate solution. Leaching of catalysts, yields, and turnover frequencies in these flow reactions were comparable with prior results obtained with the same phase isolable catalysts in batch reactions.