Total Synthesis of Angucyclines. Part 13: Biomimetic-type Approach to a Potential Precursor of the Landomycinone Angucyclinone

The dimethoxy naphthalene derivative 10 with two vicinal side chains was prepared by reaction of the dibromide 7 with silyl ether 8 ([Bu4N][Ph3SnF2]-catalysis) followed by Stille reaction of 9 with stannane 5. Acidic hydrolysis gave the triketo ester 11 that cyclized in a biomimetic-type reaction to the highly substituted dihydro benz[a]anthracene 12, a potential precursor of the angucyclinone landomycinone.