A Configurationally Stable Chiral Concave Imidazolinium Salt
作者:Tim Reimers、Christian Näther、Ulrich Lüning
DOI:10.1002/ejoc.201001367
日期:2011.2
salt 17 has been prepared. Salt 17 was cyclized by ring-closing metathesis, and hydrogenation gave axially chiral N-heterocyclic carbene precursor 19. The configurational stability of 19 was proven by temperature-dependent NMRstudies and also by the use of Λ-BINPHAT as a chiralshiftreagent. Compound 19 was also characterized by single-crystal X-ray diffraction.
Imidazolinium moieties have been incorporated into bimacrocycles to generate precursors for concave N-heterocyclic carbenes (NHCs). By using one symmetrically substituted benzene bridgehead and one naphthalene bridgehead devoid of local C2-symmetry, axially chiralconcaveimidazolinium ions have been obtained. Starting from 2,7-dihydroxy-1-nitronaphthalene (7), the phenol groups have been transformed