CITE.CC academic search helps you expand the influence of your papers.
Abstract
Small organic and metal-containing molecules (molecular mass <1,000) can catalyse synthetically useful reactions with the high levels of stereoselectivity typically associated with macromolecular enzymatic catalysts. Whereas enzymes are generally understood to accelerate reactions and impart selectivity as they stabilize specific transition structures through networks of cooperative interactions, enantioselectivity with chiral, small-molecule catalysts is rationalized typically by the steric destabilization of all but one dominant pathway. However, it is increasingly apparent that stabilizing effects also play an important role in small-molecule catalysis, although the mechanistic characterization of such systems is rare. Here, we show that arylpyrrolidino amido thiourea catalysts catalyse the enantioselective nucleophilic ring opening of episulfonium ions by indoles. Evidence is provided for the selective transition-state stabilization of the major pathway by the thiourea catalyst in the rate- and selectivity-determining step. Enantioselectivity is achieved through a network of attractive anion binding, cation-π and hydrogen-bond interactions between the catalyst and the reacting components in the transition-structure assembly. Arylpyrrolidino amidothiourea catalysts are shown to catalyse the enantioselective ring-opening of episulfonium ions by indole derivatives. Catalysis and enantioinduction are achieved by selective transition-state stabilization of the major pathway in the rate- and selectivity-determining step through a network of attractive anion-binding, cation–π and hydrogen-bonding interactions between the catalyst and the reacting partners.Cite this article
Lin, S., Jacobsen, E. Thiourea-catalysed ring opening of episulfonium ions with indole derivatives by means of stabilizing non-covalent interactions. Nature Chem 4, 817–824 (2012). https://doi.org/10.1038/nchem.1450 