[structure: see text] An efficient and versatile convergent synthesis of IB-01211 based on a combination of peptide and heterocyclic chemistry is described. The key step in the synthesis is macrocyclization through intramolecular Hantzsch formation of the thiazole ring. Dehydration of a free primary alcohol to furnish the exocyclic methylidene present in the natural product was applied during the macrocyclization.

Synthesis of IB-01211, a Cyclic Peptide Containing 2,4-Concatenated Thia-and Oxazoles, via Hantzsch Macrocyclization. -(HERNANDEZ, D.; VILAR, G.; RIEGO, E.; CANEDO LIBRADA M.; CUEVAS, C.; ALBERICIO*, F.; ALVAREZ, M.; Org. Lett. 9 (2007) 5, 809-811; Parc Cientific Barcelona, Univ. Barcelona, E-08028 Barcelona, Spain; Eng.) -Nuesgen 30-171