A new strategy for the synthesis of taurine derivatives using the ‘safety-catch’ principle for the protection of sulfonic acids
作者:Sonja Seeberger、Roger J. Griffin、Ian R. Hardcastle、Bernard T. Golding
DOI:10.1039/b614333d
日期:——
The safety-catch principle has been applied for the development of a new method for protecting sulfonic acids. 2,2-Dimethylsuccinic acid was reduced to 2,2-dimethylbutane-1,4-diol, which was selectively silylated to give 4-(tert-butyldiphenylsilanyloxy)-2,2-dimethylbutan-1-ol. Reaction of the latter compound with 2-chloroethanesulfonyl chloride in the presence of triethylamine afforded 4-(tert-butyldiphenylsilyloxy)-2,2-dimethylbutyl ethenesulfonate directly. The ethenesulfonate underwent Michael-type addition with secondary amines to give protected derivatives of taurine (2-aminoethanesulfonic acid). Deprotection was achieved on treatment with tetrabutylammonium fluoride, whereby cleavage of the siliconâoxygen bond led to an intermediate alkoxide that immediately cyclised to 2,2-dimethyltetrahydrofuran with liberation of a sulfonate. Pure sulfonic acids were obtained from the crude product by ion exchange chromatography on a strongly basic resin, which was eluted with aqueous acetic acid. The method developed should be generally applicable to the protection of sulfonic acids and is amenable to a multiparallel format.
安全捕获原理被用于开发一种保护磺酸的新方法。将 2,2-二甲基丁二酸还原为 2,2-二甲基丁烷-1,4-二醇,然后将其选择性地硅烷化,得到 4-(叔丁基二苯基硅氧基)-2,2-二甲基丁烷-1-醇。在三乙胺存在下,将后一种化合物与 2-氯乙烷磺酰氯反应,可直接得到 4-(叔丁基二苯基硅氧基)-2,2-二甲基丁基乙烯磺酸盐。乙烯磺酸盐与仲胺发生迈克尔式加成反应,得到牛磺酸的受保护衍生物(2-氨基乙磺酸)。在用四丁基氟化铵处理时,硅氧键裂解产生中间烷氧基,立即循环到 2,2-二甲基四氢呋喃中,并释放出磺酸盐,从而实现脱保护。通过在强碱性树脂上进行离子交换色谱,并用乙酸水溶液洗脱,从粗产物中获得了纯磺酸。所开发的方法应普遍适用于磺酸的保护,并可用于多平行格式。