Alkoxybenzyl alcohol resins Wang resin

For the Fmoc/tBu approach, several handles and resins are available for the synthesis of free peptide acids. Among the most conunonly used are the Trt(2-Cl)-Cl resin 2, the 4-alkoxybenzyl alcohol resin (Wang resin, 7),P 1 and the 4-(hydroxymethyl)phenoxyacetic acid (HMPAA, and 3-[4-(hydroxymethyl)phenoxy]propanoic acid (HMPPA, 9)1 han-... 

Wang SS. p-Alkoxybenzyl alcohol resin and p-alkoxybenzyloxycarbonylhy-drazide resin for solid-phase synthesis of protected peptide fragments. J Am Chem Soc 1973 95 1328-1333. 

Wang, S.-S. p-Alkoxybenzyl Alcohol Resin and p-Alkoxybenzyloxycar-bonylhydrazide Resin for Solid Phase Synthesis of Protected Peptide Fragments, J. Am. Chem. Soc. 1973, 95, 1328-1333. 

The Wang linker 1.1 (57) is a very popular choice that is based on ap-alkoxybenzyl alcohol moiety. It is typically cleaved by trifluoroacetic acid (TFA)-DCM 1/1 in 30 min at room temperature (rt) to produce carboxylic acids or alcohols. Two slight modifications to this linker have produced the super-acid-sensitive resin (SASRIN)... 

In a related study, Lusinchi [11] reported the synthesis of a new soluble polymer containing a p-alkoxybenzyl alcohol linker, analogous to Wang resin. The polymer was utilized in intermolecular radical addition reactions. The polymer was synthesized by subjecting xanthate 65, formed in three steps from alcohol 63, to styrene polymerization in the presence of lauroyl peroxide... 

In the design of a handle, the presence (once anchored to the solid support) of the carboxamido moiety has to be taken into account, because it can modify the conditions required for the cleavage step. This is especially important in those handles that are labile in the presence of acids and bases. Thus, the ester bond formed between the first amino acid and a 4-hydroxymethylphenoxyacetamidomethyl resin is more stable to TFA than when the first amino acid is anchored to the Wang resin, which also incorporates a 4-alkoxybenzyl alcohol.f In order to circumvent this effect, additional methylene groups should be added. 

Alcohols can be immobihzed directly on Wang resins as p-alkoxybenzyl ethers. These are stable to a variety of reaction conditions, and the final compounds are cleaved by mild add treatment [68]. As a further alternative, alcohols can also be... 

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