Synthesis of the 1,6,8-trioxadispiro[4.1.5.2]tetradec-11-ene ring system present in the spirolide family of shellfish toxins and its conversion into a 1,6,8-trioxadispiro[4.1.5.2]-tetradec-9-en-12-ol via base-induced rearrangement of an epoxide
作者:Margaret A. Brimble、Daniel P. Furkert
DOI:10.1039/b412883d
日期:——
mixture of 12a : 12b : 12c. The major bis-spiroacetal 12a underwent stereoselective epoxidation using dimethyldioxirane to alpha-epoxide 33a. Subsequent base induced rearrangement of this epoxide 33a using lithium diethylamide in pentane afforded allylic alcohol 34a, that was converted to the more thermodynamically favoured homoallylic alcohol 11a upon treatment with lithium pyrrolidinylamide in tetrahydrofuran
据报道,存在于贝类毒素螺旋藻B和D 2中的1,6,8-三恶二螺[4.1.5.2]十四烷基-11-烯12的合成。通过使用碘代苯二乙酸盐和碘对羟烷基二氢吡喃14和羟烷基螺缩醛13进行迭代自由基氧化环化反应来构建两个螺中心。该程序最初提供了双-螺缩醛12a:12b:12c:12d的1:1:1:1混合物,但是随后的酸催化平衡提供了12a:12b:12c的3:1:1的热力学混合物。主要的双螺缩醛12a使用二甲基二环氧乙烷经立体选择性环氧化成α-环氧化物33a。随后在戊烷中使用二乙氨基锂将碱引起的环氧化物33a重排,得到烯丙基醇34a,在四氢呋喃中用吡咯烷基氨基锂处理后,其转化为热力学上更优选的均丙醇11a。均丙醇11a具有C-12上的羟基,这是引入螺旋体B 1和D 2中此位置存在的叔醇基所需要的。