A Readily Available Chiral Ag-Based N-Heterocyclic Carbene Complex for Use in Efficient and Highly Enantioselective Ru-Catalyzed Olefin Metathesis and Cu-Catalyzed Allylic Alkylation Reactions
作者:Joshua J. Van Veldhuizen、John E. Campbell、Russell E. Giudici、Amir H. Hoveyda
DOI:10.1021/ja050179j
日期:2005.5.1
ligand does not require optically pure biaryl amino alcohols, its synthesis is significantly shorter and simpler than the related first generation ligands bearing a chiral binaphthyl-based amino alcohol. The chiral NHC ligand can be used in the preparation of highly effective Ru- and Cu-based complexes (prepared and used in situ from the Ag(I) carbene) that promote enantioselective olefin metathesis and
Synthesis, Isolation, Characterization, and Reactivity of High-Energy Stereogenic-at-Ru Carbenes: Stereochemical Inversion through Olefin Metathesis and Other Pathways
作者:R. Kashif M. Khan、Adil R. Zhugralin、Sebastian Torker、Robert V. O’Brien、Pamela J. Lombardi、Amir H. Hoveyda
DOI:10.1021/ja3056722
日期:2012.8.1
The synthesis, isolation, purification (routine silica gel chromatography), and spectroscopic characterization of high-energy endo stereogenic-at-Ru complex isomers, generated by ring-opening/cross-metathesis (ROCM) reaction of the corresponding exo carbenes, are disclosed. We provide experimental evidence showing that an endo isomer can undergo thermal or Bronsted acid-catalyzed polytopal rearrangement, causing conversion to the energetically favored exo carbene.
Efficient Enantioselective Synthesis of Functionalized Tetrahydropyrans by Ru-Catalyzed Asymmetric Ring-Opening Metathesis/Cross-Metathesis (AROM/CM)
作者:Dennis G. Gillingham、Osamu Kataoka、Steven B. Garber、Amir H. Hoveyda
DOI:10.1021/ja0458672
日期:2004.10.1
efficient method for enantioselectivesynthesis of highly functionalized pyrans (up to 98% ee) through Ru-catalyzed asymmetricring-opening metathesis/cross-metathesis is described. Reactions are promoted by a recyclable chiral Ru-chloride or a new chiral Ru-iodide complex; the latter catalyst is less efficient but gives rise to significantly higher levels of enantioselectivity. Catalytic reactions can be