SynPhase™ Crown cleavage

SynPhase crowns may be used to perform large numbers of optimization reactions in parallel. This library of reaction conditions may be analyzed by assaying product purities after cleavage from the solid phase using high-throughput techniques such as HPLC and ESMS. Overall, this approach can greatly reduce the time required for this critical step of compound library development. 

A wide range of linker groups are currently used with SynPhase crowns. They accommodate formation of the following functional groups upon cleavage carboxylic acids, primary and secondary amides, sulfonamides, alcohols, phenols, amines, anilines, anilides, hydroxymates, aldehydes, ketones, and thiols. 

Lambert and co-workers49 (University of Melbourne) synthesized a library of cyclic thioether peptides with a pendant 9-aminoacridine moiety as a DNA-binding agent 81. Diversity in the library was achieved by assembling every permutation of four amino acid residues within the cyclic peptide (Scheme 24). The linear peptides 80 were synthesized in parallel with standard Fmoc chemistry on SynPhase Crowns functionalized with a Rink linker. The acridine moiety was incorporated onto the C-terminal lysine side chain using 9-phenoxyacridine. Cysteine deprotection and peptide cy-clization also took place under the acidic conditions used for the cleavage of 80 from the solid support. The library of cyclic thioether peptides 81 was obtained in high yields and purity (11 of 12 members had purities >95%). 

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