Tandem Radical Cyclization Reactions, Initiated at Nitrogen, as an Approach to the CDE-Tricyclic Cores of Certain Post-secodine Alkaloids
作者:Martin G. Banwell、David W. Lupton
DOI:10.3987/com-05-10575
日期:——
The nitrogen-radical precursors (10-15) have been prepared and subjected to reaction conditions expected to promote tandem radical cyclization sequences leading to the CDE-tricyclic frameworks associated with alkaloids such as vindoline (1) and ibophyllidine (2). In the event, each of precursors (10, 11, 12 and 13) participated in the desired processes and thus providing products, (28, 29, 30 and 31)
已制备氮自由基前体 (10-15) 并使其经受预期促进串联自由基环化序列的反应条件,从而产生与生物碱如万年灵 (1) 和冰毒碱 (2) 相关的 CDE-三环骨架。在这种情况下,每个前体 (10, 11, 12 和 13) 都参与了所需的过程,因此分别提供了产品 (28, 29, 30 和 31),这些产品分别体现了与 ibophylidine (2) 相关的环系统。相比之下,PTOC-氨基甲酸酯 (12) 的高级同系物 (14) 在暴露于自由基链引发条件时分解,而 N-氯代类似物 (15) 简单地进行还原脱氯得到化合物 (27)。因此,标题过程似乎不太可能为与vindoline 型生物碱相关的CDE-三环系统提供有用的方法。