A convenient synthesis of estrone and 11-methylequilenines based on the thermal elimination of .BETA.-ketosulfoxides.
作者:TAKAO KUROSAWA、MASAHIKO TOHMA、YUJI OIKAWA、OSAMU YONEMITSU
DOI:10.1248/cpb.26.1533
日期:——
The thermal elimination of β-ketosulfoxides (3, 4, 5) derived easily from methyl 4-(3-methoxyphenyl) butyrate (1) gave 6-(3-methoxyphenyl) hex-1-en-3-one (6), which was condensed with 2-methylcyclopentane-1, 3-dione (8) to yield the triketone (7), one of key intermediates of Smith's estrone synthesis. Compound 7 was cyclized to the unsaturated diketone (9), which was converted to estrone methyl ether (13) by the established procedures. When the mixture of 3 (or 4) and 8 was heated, 7 was directly formed in a good yield. Moreover, heating of 5 and 8 gave 9, though in less satisfactory yield. The over-all yield of this simple and short cut synthesis of estrone methyl ether (13) from the starting material (1) was 34%, nearly twice of the original Smith method. This method also applied for the synthesis of 11α-methylequilenine methyl ether (20) and 11α-methylisoequilenine methyl ether (19) via the prior introduction of a methyl group to 3 yielding the β-ketosulfoxide (14) in 40% over-all yield.
从 4-(3-甲氧基苯基)丁酸甲酯(1)中容易得到的 β-酮基硫醚(3、4、5)经热消除后得到 6-(3-甲氧基苯基)己-1-烯-3-酮(6),它与 2-甲基环戊烷-1,3-二酮(8)缩合后得到三酮(7),这是史密斯合成雌酮的关键中间体之一。化合物 7 环化成不饱和二酮(9),然后按照既定程序转化成雌酮甲醚(13)。将 3(或 4)和 8 的混合物加热,可直接生成 7,收率很高。此外,加热 5 和 8 还可以得到 9,但收率较低。用这种简单快捷的方法从起始原料(1)合成雌酮甲醚(13)的总收率为 34%,几乎是原始史密斯方法的两倍。这种方法也适用于合成 11α-甲基喹啉甲醚 (20) 和 11α-甲基异喹啉甲醚 (19),方法是事先在 3 上引入一个甲基,生成 β-酮亚砜 (14),总产率为 40%。