- Protected amino acids and process for the preparation thereof
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Compounds of the formula I, STR1 in which 'R1 is an amino protective group, and n stands for 1 or 2, R1 denotes hydrogen or an amino protective group, R2 denotes hydrogen or a carboxyl protective group and R3 denotes triphenylmethyl, 4-monomethoxy-trityl or 4,4'-dimethoxy-trityl, and reactive carboxylic acid derivatives of such compounds of the formula I in which R2 stands for hydrogen, are described. These compounds can be used as starting materials for the preparation of peptides. They are more suitable for this than are analogous compounds of the formula I in which R3 denotes hydrogen or one of the carbamoyl protective groups hitherto customary.
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- Protection of carboxamide functions by the trityl residue. Application to peptide synthesis
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Carboxamide functions may be tritylated by an acid-catalyzed reaction with triphenylmethanol and acetic anhydride in glacial acetic acid. The ω-trityl group of asparagine and glutamine is cleavable by TFA, but stable to strong mineral acids in aqueous solution, as well as to nucleophiles and bases. In peptide syntheses, it is ideally suited for combination with side-chain protections of the t.butyl-type.
- Sieber,Riniker
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p. 739 - 742
(2007/10/02)
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