ABSTRACT
While the majority of reports of parallel and combinatorial synthesis still involve the attachment of reactants (either reagent or substrate) to an insoluble support, there have been numerous publications describing parallel synthesis using soluble polymers [20,37,38]. The major advantage that use of a soluble polymer holds over a “classical” insoluble polymer (e.g., polystyrene beads) is that reactions occur entirely in the solution phase, so that little or no modification of a traditional non-polymer-supported synthesis is
necessary. A second advantage is that reaction kinetics are often faster with the soluble polymer than with a two-phase system. Upon completion of the reaction, the desired product (attached to the soluble polymer) is isolated by precipitation of the polymer, by extraction (e.g., into a fluorous
solvent when using a fluorous polymer), or by means of separation based on molecular weight (such as equilibrium dialysis or size exclusion chromatography). Some examples of soluble polymers include polyethylene glycol (PEG), polyvinyl alcohol, non-crosslinked polystyrene, and polyacrylic acid (Fig. 31). Since the polymer-bound component can be separated from the other reagents at the end of the reaction, excess reagents may still be used to drive reactions to completion, affording high yields and purities of products.
