Abstract:
The synthesis of pyranonaphthoquinone-spiroacetals (3 and 4), which are synthetic analogues of the pyranonaphthoquinone antibiotic griseusin A (1) is reported. The oxygenated substituents on the spiroacetal ring were introduced onto the key naphthalene intermediate (5) using an anti asymmetric aldol reaction. The pyranonaphthoquinone skeleton was then assembled via furofuran annulation to naphthoquinone (22) to construct a furonaphthofuran ring followed by oxidative rearrangement to the furonaphthopyran ring.
