Backbone linkers

Bourne GT, Meutermans WDF, Alewood PF, McGeary RP, Scanlon M, Watson AA, Smythe ML. A backbone linker for Boc-based peptide synthesis and on-resin cyclization Synthesis of stylostatin 1. J Org Chem 1999 64 3095-3101. 

Fig. 3. Several linkers used for cyclization. For backbone linkers 1 and 2 small libraries of cyclic peptides have been synthesized (26-28). Activated linkers 4 to 6 have also been used in cyclic peptide libraries (29-32).

Gu, W. and Silverman, R. B. (2003) New stable backbone linker resins for solid-phase peptide synthesis. Org. Lett. 5, 415 18. 

Two new cyclic heptapeptides, scytalidamides A 43 and B 44, were isolated from the culture broth of a marine fungus, Scytalidium sp., collected from the Bahamas. Compounds 43 and 44 showed moderate in vitro cytotoxicity toward HCT-116 human colon adenocarcinoma with IC50 values of 2.7 and 11.0 pM, respectively. Both compounds displayed moderate cytotoxicity in the NCI 60 cell-line panel with mean GI50 values of 7.9 and 4.1 pM for 43 and 44, respectively. The most sensitive cell lines were MOLT-4 leukemia (3.0 pM) for 43 and Uacc-257 melanoma (1.2 pM) for 44. The total syntheses of scytalidamide A 43 was achieved on solid phase using two different resins, a phenylalanine silane resin and a 4-methoxybenzaldehyde backbone linker resin. ... 

Moisture-Curing Silicones. The formulation of moisture-curing sHicones includes a sHicone polymer, filler, a moisture-reactive cross-linker, and sometimes a catalyst. The most common sHicone polymer used in sealant formulations is an alternating sHicon—oxygen backbone with methyl groups attached to the sHicon such as the sHicone polymer (1). 

There is a large range of resins available for SPOS. These resins are derivatised polymer supports with a range of linkers. The roles of linkers are (i) to provide point(s) of attachment for the tethered molecule, akin to a solid supported protecting group(s), (ii) to provide distance from the polymeric backbone in order to minimise interactions with the backbone, (iii) to enable cleavage of product molecules under conditions compatible with the stability of the molecules and the reaction conditions employed for chemical transformations. Hence in order to... 

Both the main chain and side chains can greatly influence die properties of polymers. By varying the side chains and using different linkers, properties of polymers such as die solubility and conjugation along the polymer backbone can be greatly altered. 

Introduction of side chains will generally increase the solubility of the polymers but usually disrupt the conjugation along the polymer backbone. By properly choosing the side chains and linker, it is possible to prepare polymers with desired conjugation and solubilities.40... 

Jensen KJ, Alsina J, Songster MF, Vagner J, Albericio F, Barany G. Backbone amide linker (BAL) strategy for solid-phase synthesis of C-terminal-modified and cyclic peptides. J Am Chem Soc 1998 120 5441— 5452. 

In some cases, oxygen and nitrogen have been used as linkers to the backbones that are variations of those described previously (Fig. 23.4). 

BACKBONE AMIDE LINKER (BAL) STRATEGY FOR SOLID-PHASE SYNTHESIS... 

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