Osmium(II)-, Rhenium(I)-, and Tungsten(0)-Promoted Dipolar Cycloaddition Reactions with Pyrroles: Exploiting the Azomethine Ylide Character of This Heterocycle

Complexes of the form TpRe(CO)(MeIm)(η2-pyr) and TpW(NO)(PMe3)(η2-pyr) (where pyr =
1-methylpyrrole, 2-methylpyrrole, and 2,5-dimethylpyrrole) were prepared and combined with a range
of potential dipolarophiles. In several cases a dipolar cycloaddition resulted in the formation of
7-azanorbornene complexes (one crystal structure for each metal is presented), but attempts to develop
a general route to the organic bicyclic system were unsuccessful. Using the complex [Os(NH3)5(η2-pyrrole)]2+ an organic cycloadduct was successfully prepared with dimethyl fumarate, and this complex
was elaborated into advanced synthons to several naturally occurring pyrrolizidines.

合成了通式为TpRe(CO)(MeIm)(η²-pyr)与TpW(NO)(PMe3)(η²-pyr)的金属配合物（其中pyr代表1-甲基吡咯、2-甲基吡咯及2,5-二甲基吡咯），并将其与一系列潜在亲偶极体进行反应。在多个反应案例中，偶极环加成反应生成了7-氮杂降冰片烯配合物（每种金属均配有一个晶体结构），但试图开发制备该有机双环体系的通用路线的尝试均未成功。以配合物[Os(NH3)5(η²-吡咯)]²+为反应物，成功与富马酸二甲酯合成了有机环加合物，该配合物可进一步衍生为多种天然吡咯里西啶类生物碱的高级合成子。