N. Katagiri, Tetsuzo Kato, J. Nakano
Jul 25, 1982
Citations
0
Influential Citations
13
Citations
Journal
Chemical & Pharmaceutical Bulletin
Abstract
The synthesis of naturally occurring anthracene-9, 10-diones (12a-c) from ethyl 2-benzyl-4, 6-dihydroxybenzoates (7a-d), prepared by the reaction of diketene with ethyl 4-aryl-3-oxobutanoates (6a-d), is described. Reaction of diketene with 6a-d in the presence of sodium hydride in tetrahydrofuran gave 7a-d. Treatment of 7a-d with methyl iodide in the presence of potassium carbonate, followed by ethanolic sodium hydroxide, gave 2-benzyl-4, 6-dimethoxybenzoic acids (9a-d). Cyclization of 9a-d with trifluoroacetic acid-trifluoroacetic anhydride gave anthrone derivatives (10a-d) which, without purification, were oxidized with chromium trioxide to give the anthracene-9, 10-diones (11a-d). Selective demethylation of 11a-c with boron tribromide gave 12a-c.