Solid supports PEGA

The Sharpless asymmetric dehydroxylation of resin-bound olefins was monitored using 3H, 13C and HMQC HRMAS NMR.63 The authors found 13C HRMAS NMR to be particularly suited to evaluating the progress of this reaction and permitted the enantiomeric excesses of the products to be determined before they were cleaved from the support. Most importantly, they were able to evaluate the types of substrates amenable to this reaction on solid supports, showing the ability of HRMAS NMR to contribute to synthetic questions. Transformation of the unnatural amino acid Lys(NH2) on a poly (ethylene glycol)-dimethylacrylamide (PEGA) resin to 6-hydroxynorleucine was confirmed by application of TOCSY HRMAS experiments.64... 

Solid-supported SIMes functionalized complex 181 has been prepared for use as a recoverable olefin metathesis catalyst for use in methanol and water.Using a commercially available amine-functionalized PEG-based support (PEGA-NH2), 181 was prepared in three steps (Scheme 72). It was found to promote relatively efficient ring-closing and cross-metathesis reactions. 

PEGA beads have been employed to study protein-ligand interactions e.g. by Meldal et a/. 23 who generated a library of polymer-bound protease substrates, which were C-terminally linked to a fluorescence donor (2-aminobenzoic acid) and A-terminally fixed to a fluorescence acceptor (3-nitrotyrosine). The beads were subjected to the endoprotease Subtilisin Carlsberg whereby after proteolytic cleavage the fluorescence donor remains on the solid support. Fluorescent beads were subjected to sequence analysis, which not only revealed the sequence of the cleaved fragment but also the cleavage site. 

Gr0tli and coworkers used various resin supports and linkers and employed thermal heating or microwaves to turn dipeptides into DKPs (Scheme 9 1). They found that PEGA-Ser resin is a good choice with water as the solvent under thermal heating for the formation of DKPs, while for microwave reactions, other solid supports in toluene /-butanol (1 4) or /-BuOH, or toluene at 120°C, also performed very well. 

The dendrons on solid support, reviewed in this chapter, display a substantial structural and applicative diversity. Although these hybrids are usually prepared on polystyrene or sihca cores, additional organic (PEGA, hydroxyethyl methacrylate) and inorganic (carbon... 

Fig. 1 Phosphopeptide synthesis on solid support General conditions. (I) monoBAL, HBTU, HOBt DIEA, NMP (II) H-Gly-NHz, NaBHsCN, AcOH-MeOH (1 99) (HI) Fmoc-Gly-OH, DIG. DCM-NMP (9 1) (/v) Fmoc-Aaa-OH, HBTU, HOBt DIEA, NMP (i AC2O, DCM (vl) TRA-TES-H2O (95 2.5 2.5). MM microwave heating, 60 °C Pphosphate group on Ser, Thr, orTyr PEGA poly[acryloyl-bis(aminopropyl)polyethylene glycol] r6Tenta(3el FSpolystyrene [14,15,29]...

Meldal and coworkers developed polyacrylamides cross-linked with poly(ethylene glycol), referred to as PEGA, as supports for solid-phase synthesis and on-bead enzymatic assays [181-183]. Functionalization of the polymer was performed in a similar fashion as in the case of other polyacrylamides, i.e. either by copolymerization with N-acryloylsarcosine ethyl ester followed by aminolysis with ethylenediamine, or by copolymerization with an amino group containing monomer. The monomers used for a high-capacity (0.4-0.8 mmol/g [182]) and a low-capacity (0.2-0.4 mmol/g [181]) PEGA support are sketched in Figure 2.7. 

Solid-phase click chemistry in organic solvents (e.g., DMF and THF) works well, seemingly independent of the support Resins such as polystyrene and polyethylene glycol (PEGA) attest to tolerance to both nonpolar and polar types. As outlined in the original Meldal el al. papers, novel triazole-containing polypeptides... 

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