Total Synthesis of Angucyclines. Part 15: A Short Synthesis of (±)-6-Deoxybrasiliquinone B

The 6-deoxybrasiliquinones 2 and 14a were prepared by a boron triacetate mediated Diels–Alder reaction of juglone (9) with the crude mixture of ethoxy dienes 6 and 7. The primary non-aromatic Diels–Alder product 10 was isolated after reaction of the dienol 8 with 9. Dimethyldioxirane oxidation of 10 afforded the epoxide 11.