Photochemical High-yield Preparation of Tricyclo [3.3.0.02,8]octan-3-ones. Potential Synthons for Polycyclopentanoid Terpenes and Prostacyclin Analogs. Preliminary Communication
作者:Martin Demuth、Palaykotai R. Raghavan、Charles Carter、Koichi Nakano、Kurt Schaffner
DOI:10.1002/hlca.19800630836
日期:1980.12.10
Three-step syntheses and the resolution into the enantiomers are reported for the tricyclo[3.3.0.02,8]octan-3-ones 7–9, which are destined to serve as synthons for polycyclopentanoid terpenes and prostacyclin analogs. Routine overall yields of ca. 75% for 7, 40% for 8, and 46% for 9 are obtained, with 2-chloroacrylonitrile and 1,3-cyclohexadiene (for 7) and 1-methyl-1,4-cyclohexadiene (for 8 and 9)
据报道三环[3.3.0.0 2,8 ]辛烷-3-酮7-9的三步合成法和拆分为对映体的化合物,注定将其用作多环戊烷萜烯和前列环素类似物的合成子。常规总产量约为 75%的7,40%为8,以及46%9获得,用2-氯丙烯腈和1,3-环己二烯(7)和1-甲基-1,4-环己二烯(为8和9)作为起始材料。关键步骤是三重敏化对乙二酸-π-甲烷的β,γ-不饱和酮1-3的光重排分离产物的产率为80-90%,量子产率为0.5-1.0。酮1及其光异构体7的外消旋物已通过色谱分离合适的非对映异构体缩醛混合物而分离。另一方面,用旋光性供体(-)- 14进行1敏化,仅得到不切实际的最大对映体过量10%(-)- 7。