Synthesis of arizonin C1

Abstract

The first syntheses of the pyranonaphthoquinone antibiotics 5-epi-arizonin B1 16, 5-epi-arizonin C1 15 and arizonin C1 3 are described. The key steps involve addition of 2-trimethylsilyloxyfuran 12 to the 2-acetylnaphthoquinone 11 affording the adduct 13 which undergoes oxidative rearrangement to a pyranonaphthoquinone system 14 upon treatment with ceric ammonium nitrate. The regioselective synthesis of naphthoquinone 11via oxidation of ketone 10 is described wherein 10 is prepared via addition of furan to 3,4-dimethoxydehydrobenzene followed by treatment with acid.