Synthesis of ansamycins: An approach to the naphthoquinone portion of the rifamycins and streptovaricins

Naphthoquinone $\text{1}$, a fully functionalized model for intermediates in ansamycin synthesis, was prepared by the intramolecular Claisen condensation of benzofuran $\text{9}$ followed by oxidation of the novel tricyclic compound $\text{10}$.     

Group selective reduction of acetals related to the ansa chain of the streptovaricins: Conformational and stereochemical analysis

The group selective reductive cleavage of benzylidene acetals derived from diols containing chains equipped with a central chirotopic, nonstereogenic carbon atom is reported. The stereochemistry that is obtained at the central carbon is suitable for application to the synthesis of members of the streptovaricin class of antibiotics.