Studies of Unusual Amino Acids and Their Peptides. XII. The Chemistry of N-(Carboxymethyl)amino Acids. I. The Preparation, Properties, and Characterization of N-(Carboxymethyl)amino Acids and Their Esters

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Abstract N-Carboxymethyl(Cm-)amino acids and their mono- and diesters were prepared by several routes, and their physical and chiroptical properties were compared with those of the parent amino acids and their esters. The isolation procedure was improved for the preparation of the free Cm-amino acids obtained from the corresponding amino acids and bromoacetic acid; the aimed-at compounds were also obtained by the catalytic hydrogenolysis of the dibenzyl esters. The isomeric pairs of monoalkyl esters of Cm-amino acids were similarly accessible via the benzyl alkyl esters. The diesters proved to be suitable for the GLC and MS analyses of Cm-amino acids. All the free Cm-l-amino acids and the dicyclohexylammonium salts of their N-ethylthiocarbonothioyl derivatives show positive Cotton effects at 200–225 nm and at 335–350 nm respectively in CD measurements; therefore, these correlations can be used for the configurational assignments of Cm-amino acids.