Studies Towards the Synthesis of Phorbazoles A–D: Formation of the Pyrrole Oxazole Skeleton

Abstract

Synthetic approaches towards the synthesis of the pyrrole oxazole skeleton of phorbazoles A–D are described. An efficient synthesis of the pyrrole oxazole skeleton (19) from pyrrole and 4- methoxyacetophenone was developed. In the key step, cyclodehydration of the amide (16) resulted in formation of the diprotected pyrrole oxazole (17). Subsequent deprotection of the diprotected pyrrole oxazole (17) gave the target phorbazole skeleton (19).