CONVERGENT SYNTHESIS OF (-)-MIRABAZOLE-B USING A CHLOROIMIDAZOLIDIUM COUPLING REAGENT, CIP

(-)-Mirabazole B (1), an alkaloid consisting of four successive thiazo line/thiazole rings, has been synthesized in a convergent route. The k ey intermediate, a linear tripeptide amide 13 composing of three S-ben zyl-2-methylcysteine residues, was prepared using 2-chloro-1,3-dimethy l-imidazolidium hexafluorophosphate (CIP) in the presence of 1-hydroxy -7-azabenzotriazole (HOAt) as a coupling agent. The successive thiazol ine/thiazole rings were constructed by TiCl4-mediated cyclization foll owed by Hantzsch reaction without difficulty. (C) 1997 Elsevier Scienc e Ltd.