Reactions of Ketene Acetals. 13. Synthesis of Contiguously Trihydroxylated Naphto- and Anthraquinones

Article abstract of DOI:10.1021/jo00334a011

A regiospecific method of obtaining various quinones bearing at least three adjacent hydroxyl groups has been devised by using a new vinylketene acetal, 2-methoxy-1,1,3-tris(trimethylsiloxy)-1,3-butadiene (9b).In this way the first total syntheses of dermoglaucin (50) and ceroalbolinic acid, as its pentamethyl derivative 49, have been achieved.The structure of another natural product, capareolatin dimethyl ether, was established indirectly by the unambiguous formation of one of the two possible isomers.Advantageous preparations of "7-hydroxyemodin", copareolatin, and isoerythrolaccin derivatives 32,38, and 2, as well as those of useful intermediates such as 2- and 3-chloro-5,7-dihydroxy-6-methoxynaphthoquinones or their dimethyl ethers, are described.