Acid-promoted sequential cationic cyclizations for the synthesis of (±)-taiwaniaquinol B
作者:Shuoliang Li、Pauline Chiu
DOI:10.1016/j.tetlet.2008.01.084
日期:2008.3
A formal total synthesis of (±)-taiwaniaquinol B starting from (E/Z)-citral has been accomplished by sequential cationic cyclizations promoted by acids. The cyclization to an α-cyclogeranyl ketone derivative is promoted by Lewis acid, whereas the use of Brønsted acid promotes an olefin isomerization leading to undesired cyclizations. The final ring formation to give the hydrofluorenone skeleton is
由(E / Z)-柠檬醛开始的(±)-台湾紫杉醇B的正式全合成通过酸促进的顺序阳离子环化完成。路易斯酸促进了向α-环香叶基酮衍生物的环化,而布朗斯台德酸的使用促进了烯烃的异构化,导致不希望的环化。布朗斯台德酸促进了最终形成氢氟酮骨架的环的形成。因此,在每个步骤中酸的选择都决定了阳离子反应途径和环化结果。