4- phenoxy linker

Polar polyoxyethylene-polyoxypropylene (POEPOP) resin, deriva-tized with a 4-hydroxymethyl phenoxy linker, was used as a solid support for lanthanide triflate-catalyzed Mukaiyama-type solid-phase aldol reactions.282 The use of an aqueous solvent was found to be crucial. The reactions on an N-terminal peptide aldehyde substrate proceeded in very high yields. 

Recently, the Suzuki reaction has been extensively developed for solid-phase organic chemistry as a method allowing the parallel synthesis of potential medicinal compounds [108]. Chan et al. reported a versatile polymer-supported 4-[4-methylphenyl(chloro)methyl]-phenoxy linker for the solid-phase synthesis of pseudopeptides based on the Suzuki coupling (Eq. (67)) [109],... 

TFA) in DCM (dichloromethane). Linkers for carboxylic acids have also been designed to effect cleavage via photolysis (3-nitro-4-hydroxymethylbenzoic acid, ONb 14) [18] and flouridolysis (N-3 or 4) ((4-hydroxymethyl)-phenoxy-t-butylphenylsilyl)phenyl pentanedioic acid monoamide (PBs) 15 [19] and quinonemethide-based handle 16 [20] (Fig. 

A dendrimer containing a dye as core was synthesized by Zhang and coworkers (Fig. 7.7) [39, 40]. The feoc-protected amine endgroups of this [Gl] dendrimer were equipped with a 4-(hydroxymethyl)phenoxy acetic acid (HMPA) linker performing several reaction steps to obtain the red colored dendritic support (14). 

For solid-phase synthesis various linker molecules were constructed on the ULTRA resin 15. To determine the optimal spacer length, ULTRA resins were coupled with spacers of variable length. With 4-(4 -acetoxy-methyl-3 -methoxy-phenoxy) butyrate and a loading of 2.5 mmol/g the synthesis of heterocycles and peptides was investigated. A pyrazole carboxylic acid was prepared using a procedure established for Wang polystyrene... 

Mutter devised the [4-(2-bromopropionyl)phenoxy]acehc acid linker [41] (27, PPOA), which presumably has the mechanistic advantages of both a p-alkoxy aryl substituent and a-methyl substitution (Figure 17.6). Unfortunately, synthesis of the pentapeptide Boc-Tyr(Bzl)-Gly-Gly-Phe-Leu using the PPOA linker resulted in only a 14% yield. It was realized that PPOA is only partially compatible with nucleophiles such as hydrazine, NH3 and Triton B. 

AA, amino acid AC, acid-cleavable linker [4-(hydroxymethyl)-3-methoxy-phenoxy]acetic acid ADCC, 4-acetyl-3,5-dioxo-l-methylcyclohexane carboxylic acid AMEBA, acid-sensitive methoxybenzyl resin ANP, 3-amino(2-nitrophenyl)propionyl BAL, backbone amide linker 9-BBN,... 

A study of the pervaporation separation of ethanol/water mixtures by polydimethylsiloxane (PDMS) membranes filled with phosphazene nanotubes showed selectivity favoring water over ethanol, which corresponds to the behavior of the host polymer. The nanotubes were reported to increase permeation flux and selectivity. This conclusion was further supported by the use of a TFE/phenoxy/2-allylphenoxy phosphazene host in place of PDMS. Phosphazenes also can be used as a cross-linker for traditional organic polymers to impart greater performance in the separation of water and ethanol. In this work, poly(vinyl alcohol) membranes were cross-linked with cyclotriphosphazene substituted with 4-hydroxybenzaldehyde... 

Systematic modifications of these linker-resins by substitution with electron-donating substituents have resulted in the generation of numerous linker-resins with increased acid sensitivity. Notably, the 4-(2, 4 -dimethoxyphenylamino-methyl)phenoxy derivatized (Rink) resin 1 (7), which is cleavable by 95% v/v TFA, and the 5-(2-fluorenylmethoxycarbonylaminomethyl-3,5-dimethoxy)-phenoxyvaleric acid (PAL) linker 2 (8) addolysed by 75% v/v TFA. 

Various other linker systems such as FMOP (4-formyl-3-methoxy-phenoxy-methyl-polystyrol) linker (104) are based on reductive amination [166,203-... 

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