Darstellung von Guanidosäuren und Guanidopeptiden

The Chemistry Of The Glycocyamidines

“…The reaction is best performed in concentrated aqueous ammonia solution (108, 217, 270); this seems strange at first sight, for a great part of the S-alkylisothiourea must react obviously with the ammonia present in great excess to yield guanidine. But, keeping in mind that amino acids are easily capable of forming guanidino acids also with guanidines (see below), it becomes intelligible that many a-amino acids, e.g., alanine (217,218,270,300), «-aminobutyric acid (108, 217b), aspartic acid (217, 300), citrulline (217b), cystine (127, 179a, 217, 300), glutamic acid (217b), glycine (217,270,300), histidine (217b), leucine (217b, 218, 300), isoleucine (217b, 218, 300), norleucine (217b, 218), lysine (217, 217b), methionine (168a, 217,218,300), phenylalanine (217,300), proline (300), sarcosine (108, 270, 300), serine (217, 270, 300), threonine (217, 300), tryptamine (300), tyrosine (217), and valine (217b, 218, 300), as well as peptides, e.g., glycylglycine (217,270) and glycyl-Z-tyrosine (270), and proteins (217a, 246a, 271) may be guanylated in good yields by this method. An exception is furnished by Nethylglycine, which yields with S-ethylisothiuronium bromide under these conditions no a-(N-ethyl)glycocyamine, but instead a stable complex of iV-ethylglycine and guanidinium bromide (11a).…”

“…gives with cyanogen bromide in dry ether the dimethyl ester of V-cyanoiminodiacetic acid (XXXVIII) which, on prolonged heating with alcoholic ammonia at 85°C., is transformed to glycocyamidine-l-acetamide (XXXIX), hydrolyzable with hydrochloric acid to glycocyamidine-l-acetic acid; under somewhat more energetic conditions XXXVIII yields with alcoholic ammonia V-guanyliminodiacetic acid (XL) (270). The glycocyamidine derivative XLI is the product of an interesting guanylation reaction.…”

Guanidination of Soluble Lysine-Rich Cyanophycin Yields a Homoarginine-Containing Polyamide

“…A method for modification of functional ε-amino groups is guanidination using o-methylisourea (OMIU) (16). Lysine residues are transformed to homoarginine (2-amino-6-guanidinohexanoic acid) by reaction with OMIU under alkaline conditions (17).…”

Guanidation of amino acids and peptides

“…Reaction of 0-methylisourea with an amino group is shown in attacked by a guanidating agent under mild conditions (12,13,14,15,16,17). Since the unprotonated form of the amino group is the reactive species (Figure 2), an alpha-amino group with its lower pK would be expected to be more reactive than an epsilon-amino group at pH &-10, where the reaction is usually carried out.…”