Total synthesis of thiangazole

Article abstract of DOI:10.1016/S0040-4020(99)00604-3

A method for total synthesis of thiangazole (1), a tris-thiazoline- oxazole metabolite, is described. The key intermediate 9, a linear tetrapeptide amide composed of three S-benzyl-2-methylcysteine residues and a O-benzyl-threonine amide, was synthesized in 4 steps using 2-chloro-1,3- dimethyl-imidazolidium hexafluorophosphate(CIP)mediated activation. The successive thiazoline/oxazole rings were constructed by TiCl₄mediated cycledehydration followed by acid-catalyzed Robinson-Gabriel reaction without difficulty.