Sacrificial azomethine ylide cycloaddition controlled chemoselective nitrile oxide cycloaddition to 1-methyl-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones: formation of mono-spiro-isoxazolines
作者:Raju Ranjith Kumar、Subbu Perumal
DOI:10.1016/j.tet.2007.09.033
日期:2007.12
The 1,3-dipolar cycloaddition of an azomethine ylide to 1-methyl-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones afforded novel spiro-pyrrolidines in good yields. Further cycloaddition of these spiro-pyrrolidines with nitrile oxide afforded mono-spiro-isoxazolines in moderate yields (45–56%), presumably via a di-spiro intermediate, which undergoes a spontaneous cycloreversion of the spiro-pyrrolidine
偶氮甲碱内酯的1,3-偶极环加成反应成1-甲基-3,5-双[(E)-芳亚甲叉基]四氢-4(1 H)-吡啶酮,以良好的收率提供了新型螺吡咯烷。这些螺吡咯烷与一氧化二氮的进一步环加成,以中等收率(45-56%)提供了单螺-异恶唑啉,大概是通过双螺中间体,螺中间体经历了螺-吡咯烷单元的自发环还原。相反,将一氧化氮直接环加成到1-甲基-3,5-双[(E)-芳亚甲叉基]四氢-4(1 H)-吡啶酮中得到单螺-异恶唑啉作为次要产物,而二主要形成-螺-异恶唑啉。