Synthesis of brasiliquinones B and C, 2 and 3 and 3-deoxyrabelomycin 4a has
been accomplished in 6-7 steps from the common precursor 18b. The key naph
thalenones 6 were prepared in 5 steps from tetralone 17 in a regioselective
manner. Anionic annulation of cyanophthalide 7c with 6 readily provided te
tracyclic precursors 5 in excellent yields, sunlight-promoted photooxidatio
n of which led to the synthesis of the title compounds.