Linker functional group

References Chemical structure Cross-linker Functional group Notes... 

Sequential chemical tagging methods uses specific compounds (tags) as a code for the individual steps in the synthesis. These tag compounds are sequentially attached in the form of a polymer-like molecule to the same linker or bead as the library compound at each step in the synthesis (Figure 6.10). The amount of tag used at each step must be strictly controlled so that only a very small percentage of the available linker functional groups are occupied by a tag. At the end of the synthesis both the library compound and the tag compound are liberated from the bead. The tag compound must be produced in a sufficient amount to enable it to be decoded to give the history and hence the possible structure of the library compound. 

Figure 3-10 Common linker functional groups and the reagents that cleave the product. Note that different linkers provide different spacing and steric freedom between the product anc the support. Hf, hydrofluoric acid TfA, trifluoro-acetic acid.

For small molecule synthesis, linker-functional group combinations that are labile to TFA tend to be selected. In the absence of nucleophilic functionalities such as those described above within the target molecule, simple mixtures of TFA and dichloro-methane tend to be used for release of the product from the support as this mixture is volatile and so makes work up of the reaction a simple matter of evaporation. 

Compounds containing a (CH2)3 linkage to the POSS core have become more widely studied than many of the alkyl derivatives because of their ready preparation and because the propyl arm is the shortest linker that usually prevents the reactivity of functional groups being enhanced by the nearby silicon... 

Krier M, de Araujo-Junior JX, Schmitt M, Duranton J, Justiano-Basaran H, Lugnier C, Bourguignon JJ, Rognan D. Design of small-sized libraries by combinatorial assembly of linkers and functional groups to a given scaffold application to the structure-based optimization of a phosphodiesterase 4 inhibitor. J Med Chem 2005 48 3816-22. 

Recent developments in DNA/RNA chemical synthesis have allowed us to attach some functional groups covalently to nucleic acids, thus permitting the introduction of a functionality or properties not normally present in the native biomolecule The use of non-nucleosidic linkers is probably the most popular approach for the 5 -terminal modification of chemically synthesized nucleic acid oligonucleotides and a number of such linkers are commercially available. The linker shown in Fig. 2 is designed as a phosphoramidate derivative so that it can be incorporated into the 5 -terminus of the sequence as the last... 

Polymerization screening mns using porphyrin catalysts with different linker groups between the 700 Da polyethylene tail and the porphyrin core showed little variability. The catalytic activity for the 4 x 700 PE porphyrin catalysts with ether (5), ester (7) or polyether (8) linkers was nearly identical, with only small differences in the resin colors being noted (Figures 36.3 and 36.4). These results are consistent with literature findings that porphyrin CCT catalysts are relatively insensitive to functional groups on the equatorial plane. ... 

Cleavage of all the linkers described above provide a functional group (carboxylic acid, amide, amine, etc) at the anchoring position. Silyl-based handles 71,72, and 73 as well as germanium-based handle 74 insert a C-H bond at the anchoring position and are referred to as traceless (Fig. 15) [82-... 

Preliminary results of DNA sequence detection using the OFRR are thoroughly described by Suter, et al.32 The experimental setup described above for tracking the resonant mode shift is used. An OFRR with RI sensitivity of about 7 nm/RIU was produced and used for these experiments. The OFRR surface was functionalized with 3APS and then DMA was used as an amine-amine crosslinker. The single-stranded oligonucleotide capture probe was synthesized with an amine functional group connected to the 5 end by a 6-carbon linker, and has a 25 base-pair sequence. ... 

Figure 2. Examples of linkers which protect a specific functional group by attachment to solid support.

The notion of stabilized and sensitized protectors is pertinent to solid-phase synthesis in particular. Practically all of the linkers through which carboxy-terminal residues are attached to the solid support are composed of benzyl that has been substituted with functional groups such as dialkoxy, dimethoxyphenyl, phenyl (ben-zhydryl), diphenyl (trityl), chlorodiphenyl (chlorotrityl, see Section 5.23), or other to modify the stability of the linking bond.9-63-73... 

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