Synthese von 4,8-Dimethoxy-1,5-naphthalindiol und dessen Oxidation zu 4,8-Dimethoxy-1,5-naphthochinon

Total Synthesis and Determination of the Absolute Configuration of Parimycin

The first total syntheses of (±)-parimycin and (R)-parimycin were accomplished from O-methylnaphthazarin (6) in nine synthetic steps. Intermolecular Diels-Alder reaction of 6 with diene 7, cyclodehydrogenation catalyzed by iodine-dimethyl sulfoxide, and sodium dithionite reduction were the key steps. The absolute configuration of natural parimycin was determined to be S.

Formal total synthesis of (+)-diepoxin sigma

The highly oxygenated antifungal anticancer natural product (+/-)-diepoxin sigma was prepared in 10 steps and in 15% overall yield from O-methylnaphthazarin. Highlights of the synthetic work include an Ullmann coupling and a possibly biomimetic oxidative spirocyclization for the introduction of the naphthalene ketal as well as the use of a retro-Diels-Alder reaction to unmask the reactive enone moiety in the naphthoquinone bisepoxide ring system. A novel highly bulky chiral binaphthol ligand was developed for a boron-mediated Diels-Alder reaction that constitutes a formal asymmetric total synthesis of (+)-diepoxin sigma.