Exploiting Poly(ethylene glycol) as a Matrixfor Liquid-Phase Organic Synthesis

For many years solid polymers have been dominant both in parallel syntheses and as supports for organic reagents.1,2 However, there are a number of major concerns associated with the use of insoluble polymeric derivates under heterogeneous conditions such as lowered reactivities, sideside interactions, extended reaction times and diffision-limited reactivity. The use of soluble matrices3 such as poly(ethylene glycol)4 circumvents these problems while also allowing for routine monitoring of the reaction progress. Additionally, the basis for developing soluble polymer-supported chemistry is quite excellent since known solution-phase reaction conditions are preserved.5,6 Our efforts in this field have included the development of soluble polymer-supported combinatorial libraries,7 catalysts,8 reagents,9-11 linker strategies12,13 and synthetic methodology.14,15 This report details the development and application of a poly(ethylene glycol) bound triarylphosphine reagent and the optimization of a liquid-phase Stille cross-coupling reaction with subsequent generation of a small library of biaryl, heterobiaryl and styryl derivatives in high yields and purity.