Total synthesis of bistratamide D

The total synthesis of the macrocyclic hexapeptide bistratamide D is report ed. The synthetic strategy involved assembly of enantiomerically pure oxazo le, thiazole, and oxazoline segments derived from amino acids. Macrocycliza tion of the hexapeptidic aminooxazoline-oxazole-thiazole carboxylic acid fr agment was accomplished by activation with O-(7-azabenzotriazol-1-yl)-N,N,N ',N'-tetramethyluronium hexafluorophosphate (HATU).