Linker multifunctional

Nowadays, solid-phase synthesis has been used as a powerful tool in organic chemistry, especially to prepare small molecule libraries. New linkers to obtain different functionalities after cleavage have been developed. There are different linkers strategies (Fig. 3.2), for example traceless linkers, multifunctional linkers, safety catch linkers, fragmentation/ cycloreversion cleavage linkers, cyclization cleavage linkers, which are useful methods for combinatorial solid-phase chemistry. 

Relative hydrolysis and condensation rate studies of multifunctional silanes, Si(OR), under acidic and basic catalysis showed that the first (OR) group hydroly2es much more readily than subsequent groups (195). Sdanol—sdanol condensation is much slower than sdanol—alkoxysilane condensation, even if the alkoxysilane is monofunctional, thus suggesting that chain extension is insignificant ia the presence of a cross-linker (196—199). 

Jung N, Wiehn M, Brase S (2007) Multifunctional Linkers for Combinatorial Solid Phase Synthesis. 278 1-88... 

In the most succinct sense, a hydrogel is simply a hydrophilic polymeric network cross-linked in some fashion to produce an elastic structure. Thus any technique which can be used to create a cross-linked polymer can be used to produce a hydrogel. Copolymerization/cross-linking free radical polymerizations are commonly used to produce hydrogels by reacting hydrophilic monomers with multifunctional cross-linkers. Water-soluble linear polymers of both natural and synthetic origin are cross-linked to form hydrogels in a number of ways ... 

Triazenes are disguised diazonium ions which can be released under very mild acidic conditions. Inspired by the use of triazenes in natural product synthesis by Nicolaou et al. [127] and the pioneering work of Moore et al. [128, 129] and Tour et al. [130] in the synthesis of triazenes on a solid support and the final detachment to give iodoarenes, a whole set of triazene-based linkers has been developed (Tab. 3.10) [131]. The arene diazonium salts generated from the triazene linkers offer diverse opportunities for multifunctional cleavage. Two linkers based on tria-... 

Examples for multifunctional cleavage are given by the use of sulfone-, silyl- or triazene-linkers [202]. Wagner et al. for example used a cleavage Suzuki reaction on a sulfonium-linker (105) (Scheme 3.8) [206]. 

Fig. 11 In-situ synthesized dendrimeric structure prepared from an aminosilanized surface and multifunctional linkers [38]...

Poly(vinyl acetal)s can be formulated with other thermoplastic resins and with a variety of multifunctional cross-linkers. When cross-linking takes place the resin becomes thermoset. Thermosetting generally increases thermal stability, rigidity, and abrasion resistance, and improves resistance to solvents ancl to acids and bases. It also severely limits proccssibility by making the resin insoluble and impossible to extrude. 

Multifunctional Linkers as an Efficient Tool for the Synthesis of Diverse Small Molecule Libraries The Triazene Anchors... 

One limitation of monofunctional linkers is that they provide only one type of compound in a library. However, the so-called multifunctional linkers offer the important opportunity to incorporate additional diversity upon cleavage. In this case, the number of new functionalities (Fig. 1, type I) can multiply the number of compounds produced (Fig. 2). 

Literature precedence for multifunctional linkers can be found among various types of anchoring groups (Fig. 3). 

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