Synthesis of Analogues of Griseusin A

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.