Total Synthesis of Bistratamides G and H from Various Kinds of ΔAla and ΔAbu-Containing Oligopeptides

• Published in: Bulletin of the Chemical Society of Japan 2005-08, Vol.78 (8), p.1492-1499
• Main Authors: Yonezawa, Yasuchika, Tani, Naoki, Shin, Chung-gi
• Format: Article
• Language: English
• ISSN: 0009-2673; 1348-0634
• DOI: 10.1246/bcsj.78.1492

The total synthesis of naturally occurring bistratamides G (1) and H (2) from various kinds of dehydrooligopeptides is described. First of all, the promising building blocks of 1 and 2: N-{2-[(S)-1-(N-benzyloxycarbonyl)amino-2-methylpropyl]oxazole (4)- and N-{2-[(S)-1-(N-t-butoxycarbonyl)amino-2-methylpropyl]thiazol-4-ylcarbonyl}-L-Val-(S)NH2 (5), and methyl (S)-2-{1-[N-(3-bromo-2-oxopropanoyl)amino-2-methylpropyl]}-5-methyloxazole-4-carboxylate (6), as the left- and right-half components of the linear precursor of 1 and 2, were synthesized. Subsequent thiazolation between 4 or 5 and 6, respectively, followed by deprotection of both N- and O-protecting groups of the two formed linear trisheterocyclic peptides. By final macrocyclization using BOP as condensing agent under high-dilution conditions these peptides gave the expected 1 and 2.