| 摘要 |
Compounds of the formula <IMAGE> in which X is a group of the formula <IMAGE> Y is oxygen or sulphur; R<1> is hydrogen or lower alkoxy; R<2> is protected amino, amino or a radical of the formula -NH-R<7)<c); R<3> is carboxyl, functionally modified carboxyl or a radical of the formula -CO-R<8)<d); R<4> is lower alkyl, aryl, aryl-lower-alkyl, hydrogen or acyl; R<5> and R<6> are each lower alkyl, aryl or aryl-lower-alkyl; and R<7> and R<8> are each individually or together a residue of an amino acid or a chain of up to 20 amino-acid residues, it being possible for the amino-acid residue or residues to be protected, and the molecule containing a total of not more than 20 amino-acid residues, and salts thereof, are described. The compounds of the formula I and their salts in which R<2> is a radical of the formula (c), R<3> is a radical of the formula (d) and R<7> and R<8> together are a residue of an amino acid or a chain of up to 20 amino-acid residues, in particular those in which the amino-acid residue or the chain of amino-acid residues contains no protective group(s), are valuable aids (research tools) for determining biologically active peptide sequences; however, they are also potentially suitable as medicines. The other compounds of the formula I and their salts are valuable intermediates. |
