Abstract: New derivatives of N.sup.3 -D-trans-2,3-epoxysuccinamoyl-L-2,3-diaminopropanoic acid of formula (1) ##STR1## wherein R.sub.1 is hydrogen; or R.sub.1 is the residue of an amino acid selected from L-valine, L-norvaline, L-leucine, L-isoleucine, L-norleucine, L-methionine, L-lysine, L-2-aminobutanoic acid, L-aspartic acid and L-glutamic acid;or R.sub.1 is the residue of a dipeptide selected from L-norvalyl-L-norvaline, L-lysyl-L-norvaline, L-methionyl-L-norvaline, L-glutamyl-L-norvaline, L-norvalyl-L-methionine, L-methionyl-L-methionine, L-leucyl-L-norvaline, L-norleucyl-L-norvaline, L-valyl-L-norvaline, L-glutamyl-L-leucine, L-asparginyl-L-norvaline and L-leucyl-L-leucine;wherein R.sub.2 is hydroxyl;or R.sub.2 is the residue of an amino acid selected from L-alanine, L-methionine, L-valine, L-norvaline, L-leucine, L-isoleucine, L-norleucine and L-2-aminobutanoic acid; with the provisos that when R.sub.1 is hydrogen then R.sub.2 is an amino acid residue and that when R.sub.

Abstract: The subject of this present invention is tripeptides of N.sup.3 -4-methoxyfumaryl-L-2,3-diaminopropanoic acid of the general formula ##STR1## where R is a hydrogen atom when R.sub.1 is the dipeptide residue containing the residue of alanine, methonine, valine, leucine or norvaline, or R and R.sub.1 have the same meaning and are the residue of monoaminomonocarboxylic aminoacid, such as those of alanine, methionine, valine, leucine, or norvaline, or R is the dipeptide residue containing the residue of alanine, methionine, valine, leucine, norvaline, lysine, ornithine, sarcosine, 2,4-diaminobutanoic acid and 2,3-diaminopropanoic acid, and R.sub.1 is a hydroxide group, and the method of their obtaining. The method of obtaining involves converting N.sup.2 -tetrbutoxycarbonyl, N.sup.3 -4-methoxyfumaroyl-L-2,3-diaminopropanoic acid into an active ester which is used for acylating a dipeptide or N.sup.2 -tetr-butoxycarbonyl, N.sup.