Studies on ketene and its derivatives. CIX. Synthesis of naturally occurring anthracene-9,10-diones.
作者:NOBUYA KATAGIRI、TETSUZO KATO、JUN NAKANO
DOI:10.1248/cpb.30.2440
日期:——
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.
本文介绍了从 2-苄基-4,6-二羟基苯甲酸乙酯(7a-d)合成天然蒽-9,10-二酮(12a-c)的方法,该方法由二酮烯与 4-芳基-3-氧代丁酸乙酯(6a-d)反应制备。在氢化钠存在下,二酮烯与 6a-d 在四氢呋喃中反应,得到 7a-d。在碳酸钾存在下用碘甲烷处理 7a-d,然后用乙醇氢氧化钠处理,得到 2-苄基-4,6-二甲氧基苯甲酸(9a-d)。9a-d 与三氟乙酸-三氟乙酸酐环化后得到蒽酮衍生物 (10a-d),无需纯化,用三氧化铬氧化后得到蒽-9,10-二酮 (11a-d)。用三溴化硼对 11a-c 进行选择性去甲基化,得到 12a-c。