Formation of episulfonium ions from alkenes. Application to the synthesis of higher order carbocycles via episulfonium ion initiated polyene cyclizations
BF 3 ·CH 3 NO 2介导的多烯级联环化反应。通过非功能化3°烯烃的阳离子引发直接立体定向合成多环中间体的非常规高效方法。在(±)-紫杉二酮的全合成中的应用。
摘要:
BF 3气体在硝基甲烷中的便捷储备溶液已显示出可促进“ H +催化”多烯环化反应,并以极佳的区域和立体控制水平进行。甲直接这种新方法的用于实现阳离子polyannulations若干现代以及经典程序相比,已经结论性地确定的BF的制备优点3 ·CH 3 NO 2平台。描述了这些新条件用于阳离子多环化的简明全合成抗肿瘤药(±)-紫杉二酮。
Arylsulfenium Ion Promoted Cascade Cyclizations of Deactivated Aryldienes. An Investigation into Reagent-Based Acceleration of Cationic Annulation
作者:Scott R. Harring、Tom Livinghouse
DOI:10.1021/jo970451a
日期:1997.9.1
The efficiency of sulfenylative cyclization has been shown to be strongly influenced by both substrate substitution pattern and the structure of the external sulfenium ion source. Of the various reagents examined, 8-methoxethyl 4-chlorobenzenesulfenate (9b) has been found a particularly effective initiator for the regioselective cyclization of a range of aryldienes at low temperature.
EDSTROM E. D.; LIVINGHOUSE T., J. ORG. CHEM., 52,(1987) N 5, 949-951