A new approach to the epimeric analogue of cyclic peptides: epimerisation via oxazoles of RA-VII, anti-tumour bicyclic hexapeptide from Rubia plants

摘要

[D-Ala-4]RA-VII (9) and [D-Ala-2]RA-VII (10) were preapred from RA-VII (1), an anti-tumour bicyclic hexapeptide from Rubia plants, by conversion of its thioamide 3 into oxazoles 4 and 5 and subsequent acid-catalysed hydrolysis.