The selectivity of amino acid and peptide amidination with O-methylisourea

Selectivity of amidination using ornithine as model amino acid was investigated in detail. The results obtained were taken advantage of for studying the reactions with other polyfunctional amino acids: beta-tyrosine, isoserine, 2,3-diaminopropionic acid, 2,6-diamino-7-hydroxyazelaic acid and with the pentapeptide amide, edeine A. It was found that, if the appropriate conditions are maintained, selective amidination of more basic amino groups of polyamino compounds is possible when these groups are bound to the primary alkyl.