<i>N</i>-Hydroxy Amides. II. <i>N</i>-Benzyloxy α-Amino Acid <i>N</i>-Hydroxysuccinimide Esters and Synthesis of a Hexapeptide Having an Alternating <i>N</i>-Hydroxy Amide–Amide Sequence

Abstract

Abstract Acylation of a series of N-benzyloxy α-amino acid derivatives with N,N-phthaloyloglycine shows that the yield decreases with increasing bulkiness of the substituent even by the acyl chloride or mixed anhydride procedure, and that the use of an excess reagent or a double acylation technique is needed to attain a good yield. The low reactivity of the benzyloxyamino group enables us to utilize N-benzyloxy α-amino acid N-hydroxysuccinimide esters without N-protection in the acylation of the usual amino group. In an attempt to lengthen the chain of an N-hydroxy peptide, a hexapeptide anilide having an N-hydroxy-Dl-alanylglycyl sequence was synthesized via N-benzyloxy peptides. The complex forming tendency of the hexapeptide with iron(III) is examined.