Total synthesis of the thiazolyl peptide GE2270 A

(Chemical Equation Presented) When one door closes, another opens: In the synthesis of the thiazolyl peptide GE2270 A (1), the bonds labeled I and II at the pyridine core were established by two consecutive cross-coupling reactions. Amide bond formation (IV) and subsequent intramolecular Stille reaction (III) were more effective than the originally conceived connection strategy (III before IV). GE2270A (1) was prepared with an overall yield of 4.8% in 20 steps along the longest linear sequence.