| abstract |
The invention relates to a process for the preparation of compounds of the formula I. in which n = 1 or 2, R is hydrogen, an aliphatic, cycloaliphatic, aromatic, araliphatic, cycloaliphatic-aliphatic radical or a radical OR a or SR a , in which R "is an alkyl, aryl or heteroaryl, R 1 Is hydrogen, an aliphatic, cycloaliphatic-aliphatic, aromatic, araliphatic, heteroaromatic radical or an amino acid side chain, R 2 and R 3 are identical or different and are hydrogen, an aliphatic, cycloaliphatic, aromatic or araliphatic radical and R "+ R 5 together with the atoms carrying them form a heterocyclic ring system, which is characterized in that trifluoromethanesulfonic acid derivatives of the formulas II and 111 are reacted with amino acid esters of the formulas IV and V, respectively. The invention further relates to compounds of formula III and a process for their preparation. |