The use of endothiodipeptide anilides, which were obtained in high yields b
y a variation of the 'azirine/oxazolone method', for the synthesis of longe
r endothiopeptides is described. With this novel methodology, epimerically
pure endothiopeptides with the thiocarbonyl group next to the bulky Aib wer
e prepared in satisfactory yields. The structures of two endothiotripeptide
s and one endothiotetrapeptide were established by single-crystal X-ray cry
stallography. (C) 1999 Published by Elsevier Science Ltd. All rights reserv
ed.