Login / Signup

Neutral chiral cyclopentadienyl Ru(ii)Cl catalysts enable enantioselective [2+2]-cycloadditions.

D KosslerNicolai Cramer
Published in: Chemical science (2017)
Cyclopentadienyl ruthenium(ii) complexes with a large number of available coordination sites are frequently used catalysts for a broad range of transformations. To be able to render these transformations enantioselective, we have designed a chiral neutral CpxRu(ii)Cl complex basing on an atropchiral cyclopentadienyl (Cpx) ligand which is accessed in a streamlined C-H functionalisation approach. The catalyst displays excellent levels of reactivity and enantioselectivity for enantioselective [2+2]-cycloadditions leading to strained chiral cyclobutenes, allowing for catalyst loadings as low as 1 mol%. A very strong counterion effect of a bound chloride anion transforms the corresponding unselective cationic complex into a highly enantioselective neutral version. Moreover, by adding norbornadiene at the end of the reaction the catalyst can be recovered and subsequently reused.
Keyphrases
  • ionic liquid
  • highly efficient
  • metal organic framework
  • room temperature
  • reduced graphene oxide
  • capillary electrophoresis
  • carbon dioxide
  • visible light
  • transition metal
  • gold nanoparticles
  • energy transfer