ON THE SYNTHESIS OF (2S)-AZIRIDINE-2-CARBOXYLIC ACID-CONTAINING PEPTIDES

Optimized conditions are described for the synthesis of 1-trityl-2-azi ridine-carboxylic acid 3 (Trt-Azy-OH) and benzyl (2S)-aziridine-2-carb oxylate 6 (H-Azy-OBzl) as useful derivatives for the synthesis of N- a nd C-terminal aziridine-containing peptides. Thereby, the use of the p entafluorophenyl ester of Trt-Azy-OH was found to be the method of cho ice in acylating steps, whereas acylation of H-Azy-OBzl several classi cal methods of peptide synthesis can be successfully used. The fully p rotected aziridine-2-carboxylic acid peptides are accessible in satisf actory yields as analytically defined products, but partial or total d eprotection of these compounds again by standard procedures of peptide synthesis is surprisingly difficult in terms of satisfactory yields, whereby sequence-dependent unstability both in the reaction and purifi cation steps as well as on storage was found to strongly limit the acc essibility of these aziridine-containing peptides as promising active- site inactivators of cysteine-proteinases.