Linkers fluorene

Henkel B, Bayer E. 9-Hydroxy-9-(4-carboxyphenyl)fluorene—a new linker for solid phase synthesis. Tetrahedron Lett 1998 39 9401-9402. 

Compounds om.4 and om.5 have the same metal center as om.l, but longer conjugated linkers, which also incorporate fluorene units, and they have terminal donor groups. 2PA spectra of these molecules are characterized by... 

The fluorene linker 1.14 (71), which is easily attached to an aminomethyl PS resin, has been used to support C-terminal Boc-proteeted amino acids during oligopeptide synthesis. The cleavage of this linker requires the use of 20% piperidine, or better 20% morpholine at rt over 2 h. 

A set of fluorophores derived from naphthalene, phenanthrene, pyrene, phenazine and fluorene have been conjugated to the 5 -ends of DNA and RNA to compare their physico-chemical properties. Decreasing the Ji-electron density led to an enhancement in thermal stability, attributable to more favourable Jt-Ji interactions. Stability is further enhanced by using nitrated fluorophores. Fluorescent labelling of ODNs using oxyamino modified fluorescein has been reported by the incorporation into DNA of aldehyde functions. The aldehyde function was attached either at the 5 -end via a phosphate linker or internally via 8-mercaptobutanal. Reduction of the resulting oxime was not necessary. 

A related strategy was suggested in which one of the reactants is attached via a linker to tetrabenzo[a,c,g,i]fluorene (Tbf). The reaction product can now be purified by taking advantage of the high affinity of Tbf to charcoal in polar solvents (mixture of DCM and methanol). Desorption can be affected with non polar solvents such as toluene [144]. The method was exemplified by the synthesis of a quinolone carboxylic acid derivative (ciprofloxacin). 

Several fluorene-based linkers have been developed (Figure 15.13). In the 1980s, 9-(hydroxymethyl)fluorene-4-carboxylic acid was introduced for the synthesis of... 

We also studied the gelation properties in an amide-linked fluorene derivatives. Three simple molecules with hydrophobic groups (a fluorene or a fcrt-bufyl group) in both ends of the molecule, linked by hydrophilic carbamate enthylenediamine were selected for study (compound 12a-12c in Fig. 3.8) [29]. AU the three compounds contain two carbamate groups as a linker. 12a has fluorene group in one end... 

Glycopeptide 31 was synthesized in a custom-made, fully automatic continuous-flow peptide synthesizer constructed essentially as described elsewhere (19). A resin consisting of a cross-linked polystyrene backbone grafted with poly(ethylene glycol) chains (TentaGel , Rapp Polymer, Germany) and functionalized with the Rink amide linker (p-[a-(fluoren-9-ylmethoxyformamido)-2,4-dimethoxybenzyl]phenoxyacetic acid, Nova-biochem, Switzerland) was used for the syntheses. DMF was distilled before use. 

Two copolymers were synthesized with different ratios of the fluorene-based monomer and the fluorenylidene linker. Both polymers were obtained in high yields and high molecular weight with Mw = 55,000-89,500 Da and exhibited excellent thermal stability. Glass transition temperatures ranged from 153 °C to 197 °C with decomposition temperature (5% weight loss measurend by TGA analysis) of 440 to 450 °C. 

The monomeric subunits in 50, esters of 2,5,7-trinitrodicyanomethylene-fluorene-4-carboxylate, has previously been used to create complexes with TTE-C4P 42 [91]. This led to the consideration that ditopic systems, such as 50, that incorporates an adequate glycol-linker between the two moieties would promote the formation of supramolecular oligomers when exposed to 42. Initial evidence of a supramolecular oligomer formation came from H NMR spectroscopic studies (cf. Eig. 12.38a). As expected based on the previous studies described above, the proton resonances of the aromatic TNDCE moiety 50 were shifted upheld, while the NH proton resonances of 42 were shifted to lower held. 

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