Total Synthesis of the Antitumor Antitiotic (+-)-Fredericamycin A by a Linear Approach

摘要

A linear approach to the total synthesis of racemic fredericamcin A (1) through the oxidative intramolecular [4+2] cycloaddition of a (phenylthio)acetylene-cobalt complex is described, which is applicaable for the asymetric total synthesis of naturally occurring 1. The highlight of this work is the aromatic Pummerer-type reaction with 1-ethoxyvinyl chloroacetate, which effects the introduction of the oxygen functional group to the internal B-ring of the highly finctionalized, congested polyaromatic ABC-ring moiety.