Linkers functionalized polystyrene cross-linked with

Alkenes bound to cross-linked polystyrene can be epoxidized under conditions similar to those used in solution. The most commonly used reagent is m-chloroperbenzoic acid in DCM, but other reagents have also been used (Table 15.1). Because excess oxidant is usually required to furnish clean products, care must be taken with linkers or other functional groups prone to oxidation (ketones, amines, benzyl ethers, etc.). 

Glycopeptide 31 was synthesized in a custom-made, fully automatic continuous-flow peptide synthesizer constructed essentially as described elsewhere (19). A resin consisting of a cross-linked polystyrene backbone grafted with poly(ethylene glycol) chains (TentaGel , Rapp Polymer, Germany) and functionalized with the Rink amide linker (p-[a-(fluoren-9-ylmethoxyformamido)-2,4-dimethoxybenzyl]phenoxyacetic acid, Nova-biochem, Switzerland) was used for the syntheses. DMF was distilled before use. 

A highly efficient and recycle catalyst has been prepared by supporting the chiral Rh2(DOSP)4 to a functionalized cross-linked polystyrene resin with benzyloxymethyl pyridine linker. This supported catalyst exhibits good asymmetric catalytic activities affording the compounds 11 and 13 in similar yields and enantiomeric excess to those obtained in homogeneous reactions. 

---