Progress towards proposed biosynthetic intermediates of stephacidin A

Abstract

Progress towards three potential biosynthetic intermediates of stephacidin A are presented. The first precursor has a 7-prenylated indole ring system, the second precursor has a 7-prenyl 6-hydroxy indole ring system, and the third precursor has a 6- hydroxy indole ring system. The synthesis of the 7-prenyl indole precursor proved challenging. However, once addition of the reverse prenyl group had been achieved the synthesis proceeded without any further challenges. The remaining three steps of the synthesis should follow Williams group chemistry. Once an efficient route to the starting material of the 7-prenyl-6-hydroxy and the 6-hydroxy precursors had been achieved, the synthesis progressed nicely. However, protecting group issues at the end of the 6-hydroxy precursor synthesis prevented the final product from being obtained. This also affected the efforts towards the 7-prenyl-6-hydroxy precursor indole. Once an adequate protecting group can be found, the synthesis of the 6-hydroxy precursor should follow group chemistry to completion.