Solid-phase synthesis, branched

Scheme 5.12 Solid-phase synthesis of branched trimannan 61.68...

BW Bycroft, WC Chan, SR Chhabra, ND Hone. A novel lysine-protecting procedure for continous flow solid phase synthesis of branched peptides. (Dde group) J Chem Soc Chem Commun 778, 1993. 

Continuous reactions at the side chains of branched or comblike structured polymers play an important role in the solid-phase synthesis of peptides or oli-go-nucleotides. 

The antibiotic viscosin from Pseudomonas viscosa (Scheme 8) is a cyclo-depsipeptide acyl-ated at the N-terminus with D-3-hydroxydecanoic add.[103 112] The C-terminal carboxy group is esterified with the hydroxy group of the Thr3 residue. The synthesis of this natural product presents the problem of an ester ring closure and was performed in two steps with initial solid-phase synthesis of the Thr3-0-branched linear intermediate followed by ring closure with formation of the amide bond.1 131... 

The Mitsunobu phosphonate coupling has been adapted to the solid-phase synthesis of peptidyl phosphonates as well.1 2 In this environment, with excess phosphonate, even the more hindered, p-branched esters are formed efficiently. A series of phosphonate tripeptides have been synthesized and used to identify novel thermolysin inhibitors from a small library. (A number of other solid-phase syntheses of phosphonamidate-, 831 phosphonate-, 79 84 and phosphinate-peptides185,86 have been described however, in these instances the phosphorus bond forming steps were performed in solution, prior to solid-phase coupling.)... 

The coupling protocols described in the two previous examples can be combined to allow for the synthesis of branched carbohydrates.19 The automated solid-phase synthesis of a tetrasaccharide is illustrated in Scheme 4. Both glycosyl phosphate and glycosyl imidate building blocks were used along with acetate and levulinate esters as temporary protecting groups. 

Fig. 26 Solid-phase synthesis of a lysine-capped G3.0 polyamidourea 1—>3 C-branched bis-dendron...

In the present context, solid-phase synthesis has been used primarily for the preparation of peptide and glycopeptide dendrimers [23]. For example, a second-generation dendrimer could be prepared by successive addition of branched polyproline building blocks to a solid phase [24]. The divergent synthesis of polyamide dendrimers on polystyrenes was accomplished [25] by Frechet el al. 1991 (cf. Fig. 2.8) [26]. PAMAM dendrons could be grown up to the fourth-... 

Fromont, C., Bradley, M. High-Loading Resin Beads for Solid Phase Synthesis Using Triple Branching Symmetrical Dendrimers. Chem. Commun. 2000, 283-284. 

Kragol, G. and Otvos, LJ. (2001) Orthogonal solid-phase synthesis of tetraman-nosylated peptide constructs carrying three independent branched epitopes. Tetrahedron 57, 957-966. 

Figure 4.4. Solid phase synthesis of branched glycopeptides afforded this sialyl Lewis X glycopeptide 70.

Plante OJ, Palmacci ER, Seeberger PH. Automated solid-phase synthesis of oligosaccharides. Science. 2001 291 1523-1527. Hewitt MC, Seeberger PH. Automated solid-phase synthesis of a branched Leishmania cap tetrasaccharide. Org. Lett. 2001 2 3699-3702. 

Wu, X, Grathwohl, M, Schmidt, R R, Efficient solid-phase synthesis of a complex, branched A-glycan hexasaccharide use of a novel linker and temporary-protecting-group pattern, Angew. Chem. Int Ed, 41, 4489-4493, 2002. 

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