Polymer Libraries Preparation and Applications

Frechet and coworkers have reported the development of a functionalized polymer monolith for use in parallel solution phase synthesis in continuous flow applications [10]. In this report, the authors outline the preparation of an azalac-tone-functionalized monolith for scavenging nucleophiles. This method involves the preparation of a macroporous polyfchloromethylstyrene co-divinylbenzene) monolith via the polymerization of the relevant mixture of monomer, initiator and porogen. These are allowed to react with a free radical initiator (4-cyanovaleric acid), followed by reaction with the monomer of choice, to synthesize the functionalized monolith. The authors have thus prepared monoliths functionalized with VAZ to provide an azalactone-functionalized monolith. These monoliths were then demonstrated to completely remove amines after flowing a solution of amine in THF through the monolith for 30 min. They have also reported the reaction of these monoliths with alcohols as well. A small demonstration library of ureas was prepared and after 8 min of residence time up to 76% of the alkyl amines were found to be scavenged (Scheme 8.6). 

ATRP technique provided one of the most efficient synthetic tools for preparing many polymer libraries with weU-defined molecular profile and high degrees of functionalities. The unique capability of ATRP to synthesize polymers from inorganic/organic hybrid materials, surfaces, nanoparticles, and proteins makes this process well suited for preparing various polymeric materials for numerous biomedical applications [77, 78]. 

Different polyethylene glycol polymers were used in various papers and proved to be very reliable and useful for different classes of molecules their use for the synthesis of peptides [180, 181], of peptidomimetics [182] and of oligosaccharide libraries [183] was reported as the development and the use of a new PEG-linked traceless linker [184, 185], the selection of ligands for asymmetric Sharpless dihydroxylation [186-188], the use of PEG-linked triarylphosphines for LPCS requiring Mitsunobu or Staudinger conditions [189], the use of PEG-based supports to prepare a library of [l,4]oxazepine-7-ones [190] and the use of PEG-supported Schiff bases for the synthesis of a-substituted amino acids [191], Other examples of soluble polymers used for LPCS may include cellulose[192], polyacrylamide [193] polyvinyl alcohol [194, 195], various copolymers [196, 197] and NCPS [198-200]. Three excellent reviews [201-203] summarized the properties of PEG and other soluble polymers and their applications to the synthesis of peptides, oligonucleotides,... 

To overcome the problem of their limited range of applicability and to extend the spectrum of application other than to the imprint molecule, molecularly imprinted polymer combinatorial libraries for multiple simultaneous chiral separations have been prepared [ 191 ], demonstrating that the ligand cross-reactivities of molecularly imprinted polymers can be beneficially employed for the simultaneous separation of different stereoisomeric structures. 

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