Unsymmetrically N,N′-substituted saturated carbenes: synthesis, reactivity and preparation of a rhodium(<scp>i</scp>) carbene complex
作者:F. Ekkehardt Hahn、Duc Le Van、Martin Paas、Roland Fröhlich
DOI:10.1039/b511277j
日期:——
been investigated by NMR spectroscopy. Unsymmetrically N-iPr and N-iBu substituted N-heterocyclic carbenes undergo a slow dimerization, whereas N-tBu substituted derivatives are stable as monomeric carbenes indefinitely. The carbene ligand rac-5d has been coordinated to rhodium(I) to give the square-planar rhodium carbene complex [Cl(cod)Rh(rac-5d)]rac-6d which has been characterized by an X-ray diffraction
描述了不对称的N,N′-取代的饱和碳烯的通用合成。通过将相应的咪唑烷基-2-硫酮rac-4还原脱硫,合成了新型外消旋咪唑烷基-2-亚砜rac-5。在两个反应步骤中,由醛亚胺和仲胺制备了硫酮。通过选择合适的醛亚胺和仲胺,可以在五元N-杂环的N1,N3和C4处引入三个不同的取代基。已经通过NMR光谱研究了不对称的N,N′-取代的咪唑烷基-2-亚胺的二聚化行为(二氨基卡宾/烯四胺平衡)。N-iPr和N-iBu取代的N-杂环卡宾碳原子不对称地经历缓慢的二聚作用,而N-tBu取代的衍生物可无限期地稳定为单体卡宾。