Synthetic studies toward the kempane diterpenes. Approaches to the assembly of the ring system
作者:Guanglin Bao、Chunjian Liu、D. Jean Burnell
DOI:10.1039/b104986k
日期:2001.10.11
The ring system of the kempane diterpenes has been assembled from the Diels–Alder adduct 7 by a highly chemo- and stereoselective attack of lithium ethoxyacetylide on its apparently more encumbered carbonyl (to give 11), removal of the silyl protecting group (12 and 13), concomitant deoxygenation and ethoxyethyne solvolysis (18 and 19), reconjugation and epimerization (21), and then a series of reductive
the烷二萜的环系统是由Diels–Alder加合物7组装而成的,这是由于乙氧基乙炔锂对其明显更易缠住的羰基(生成11)进行高度化学和立体选择性的攻击,从而除去了甲硅烷基保护基(12和13),伴随的脱氧和乙氧基乙炔溶剂分解(18和19),重新结合和差向异构化(21),然后在最后的七元环(31)环化之前进行一系列还原和保护步骤。概述了另一种方法,该方法因二甲醚部分的异常环化而受阻(48)至四氢呋喃(49)。