The asymmetric totalsynthesis of the potent antitumor antibiotic fredericamycin A ((S)-1) was achieved by the intramolecular [4+2] cycloaddition of the silylene-protected styrene derivative (S)-7 followed by the aromatic Pummerer-type reaction of the sulfoxide (S)-5. Although we had already succeeded in the totalsynthesis of racemic 1 by the same approach, synthesis of its asymmetric version was
A linear approach to the totalsynthesis of racemic fredericamycin A (1) through the oxidative intramolecular [4 + 2] cycloaddition of a (phenylthio)acetylene-cobalt complex is described, which is applicable for the asymmetric totalsynthesis of naturally occuring 1. The highlight of this work is the aromaticPummerer-typereaction with 1-ethoxyvinyl chloroacetate, which effects the introduction of