Total Synthesis of Candicanoside A, a Rearranged Cholestane Disaccharide, and Its 4″-<i>O</i>-(<i>p</i>-Methoxybenzoate) Congener
作者:Pingping Tang、Biao Yu
DOI:10.1002/ejoc.200800879
日期:2009.1
Candicanoside A (1) and its 4″-O-(p-methoxybenzoate) derivative 2 are congeners of the novel 24(2322)abeo-cholestane glycosides that occur in the genus Ornithogalum indigenous to Southern Africa and have remarkable cytostatic activities. These two saponins have been synthesized starting from dehydroisoandrosterone, D-glucose, and L-rhamnose in 37 and 44 steps, respectively. The reaction protocols feature
Candicanoside A (1) 及其 4"-O-(p-甲氧基苯甲酸酯) 衍生物 2 是新型 24(2322)abeo-胆甾烷糖苷的同源物,它们存在于南部非洲土生土长的 Ornihogalum 属中,具有显着的细胞抑制活性。从脱氢异雄酮、D-葡萄糖和 L-鼠李糖开始,这两种皂苷分别经过 37 步和 44 步合成。反应方案的特点是立体控制的逐步糖基化,以糖基亚氨酸酯作为供体。重排类固醇苷元的合成采用 20-烷氧基介导的有角 18-甲基官能化、Johnson-Claisen 重排用于 C-20 烷基化、C-22 醇醛缩合和光解偶联α,β-不饱和内酯为关键步骤。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)