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HMPB and Related Resins

ChemFiles Volume 3 Article 4

PRODUCTS: 53424, 53426, 53422, 53431

 

Several highly acid-labile resins incorporate additional electron-donating methoxy-substituents in 4-alkoxybenzylalcohol-based supports. Our HMPB resins listed below consist either of aminomethyl polystyrene, BHA- or MBHA-functionalized supports acylated with Riniker’s super-acid-sensitive (4-hydroxymethyl-3-methoxyphenoxy)butanoic acid handle.(1, 2)  These resins represent excellent tools for the preparation of protected peptide acid fragments which are released by treatment with 1–5% TFA in dichloromethane. Coupling of the first amino acid residue is accomplished employing either carbodiimide/dimethylaminopyridine (DMAP) in dichloromethane,(3)  2,6-dichlorobenzoyl chloride/pyridine in DMF,(4)  or 1-(2-mesitylenesulfonyl)-3-nitro-1H-1,2,4-triazole (MSNT) in the presence of N-methylimidazole.(5, 6)  The (4-hydroxymethyl-3-methoxyphenoxy)acetic acid (HMPA) and 2-(4- hydroxymethyl-3-methoxy phenoxy)butanoic acid (HMPEA) handles vary the 4-alkoxy spacer between the o-methoxybenzyl alcohol functionality and the amide linkage to aminomethyl polystyrene. They display an increased stability towards acidolytic cleavage of the peptide chains. Please note that the abbreviation “HMPA” is also commonly used for the less acid-labile 4-(hydroxymethyl)phenoxyacetic acid “handle”.

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