Novel Synthesis of Naturally Occurring Pulvinones: A Heck Coupling, Transesterification, and Dieckmann Condensation Strategy
作者:Reinhard Brückner、David Bernier
DOI:10.1055/s-2007-983803
日期:2007.7
diimide activated arylacetic acids yielded the isomerically pure trifluoro-ethyl ( Z)-2-(arylacetoxy)cinnamates 38A- O. These were excellent substrates of potassium TERT-butoxide mediated Dieckmann condensations, and distinctly superior to fluorine-free analogues, furnishing Z-configured pulvinones 1A- O ( 1I = aspulvinone A). Cleavage of the aryl ether moieties of pulvinones 1D, E, H, N, O provided
碘芳烃与 2-乙酰氧基丙烯酸三氟乙酯 (19) 的无膦 Heck 烯基化反应立体选择性地生成三氟乙基 (Z)-2-乙酰氧基肉桂酸酯 31-34、42、44 和 51。脱乙酰化后用 N,N'-二环己基碳二亚胺酰化活化的芳基乙酸产生异构纯的三氟乙基 (Z)-2-(芳基乙酰氧基)肉桂酸酯 38A-O。这些是叔丁醇钾介导的 Dieckmann 缩合的优良底物,并且明显优于无氟类似物,提供 Z 构型pulvinones 1A-O (1I = aspulvinone A)。pulvinones 1D、E、H、N、O 的芳基醚部分的裂解提供 aspulvinone E (1R)、aspulvinone G (1S)、3',4,4'-trihydroxypulvinone (1V) 和 aspulvinones B (1X) 和H (1Y),分别。2的转换,