Synthetic studies toward an advanced intermediate of Fredericamycin A and the development and application of a novel palladium(0)-mediated spiroarylation

Abstract

An advanced intermediate 2 for the synthesis of antitumor antibiotic ($\pm$)-Fredericamycin $A$, 1, has been prepared. The synthetic route features a novel palladium(0)-mediated intramolecular spiroarylation of 3. This methodology allows access to the unusual spirocyclic ring skeleton characteristic of Fredericamycin $A$ from more readily accessible precursors, isoquinoline 4 and naphthalide 5. The syntheses of 4 and 5 are discussed. Preliminary model studies established an efficient pathway to structures related to 3. These initial studies also disclosed a means by which to generate spirocyclic ring systems of the type found in Fredericamycin $A$. (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI