Investigation of conjugate addition/intramolecular nitrone dipolar cycloadditions and their use in the synthesis of dendrobatid alkaloid precursorsNitrone dipolar cycloaddition routes to piperidines and indolizidines. Part 10. For part 9, see ref. 1.
作者:Helen T. Horsley、Andrew B. Holmes、John E. Davies、Jonathan M. Goodman、Mar�a A. Silva、Sofia I. Pascu、Ian Collins
DOI:10.1039/b402307b
日期:——
The sequential intramolecular conjugate addition of the oxime 13 followed by intramolecular dipolar cycloaddition of the intermediate nitrone 14 affords a mixture of the isoxazolidines 15, 16 and 17. The tricyclic 6,5,5-adduct 15 is believed to be the product of kinetic control and can be equilibrated with the epimeric tricyclic 6,5,5-isoxazolidine 17 through a beta-elimination/conjugate addition process
肟13的分子内共轭物的顺序添加,然后中间体硝酮14的分子内偶极环加成得到异恶唑烷15、16和17的混合物。三环6,5,5-加合物15被认为是动力学控制的产物。并且可以通过β-消除/缀合物加成过程与差向异构体三环6,5,5-异恶唑烷17进行平衡。已经开发了将酮12在热力学控制下两步转化成外消旋三环6,6,5-加合物16的步骤,所述外消旋三环6,6,5-加合物16是所有已知的组织毒素生物碱的核心前体。