Amine‐Urea‐Mediated Asymmetric Cycloadditions between Nitrile Oxides and o‐Hydroxystyrenes by Dual Activation. (24th August 2017)

• Record Type: Journal Article
• Authors: Suga, Hiroyuki; Hashimoto, Yohei; Toda, Yasunori; Fukushima, Kazuaki; Esaki, Hiroyoshi; Kikuchi, Ayaka
• Is Part Of: Angewandte Chemie. Volume 129:Number 39(2017)
• Page Start: 12098
• Page End: 12101
• Publication Date: 2017-08-24
• Subjects: Cycloadditionen -- Dichtefunktionalrechnungen -- Heterocyclen -- Organokatalyse -- Wasserstoffbrücken; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201705662
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The first example of asymmetric 1, 3‐dipolar cycloadditions between nitrile oxides and o ‐hydroxystyrenes, mediated by cinchona‐alkaloid‐based amine‐ureas is reported. The method is based on a dual activation involving both LUMO and HOMO activations. In addition to the stoichiometric asymmetric induction, a catalytic amount of amine‐urea enables the cycloadditions to proceed in an enantioselective manner. Computational studies strongly support the HOMO activation of o ‐hydroxystyrenes and LUMO activation of nitrile oxides by hydrogen‐bonding interactions with the Brønsted acid/base bifunctional catalyst.