Amine‐Urea‐Mediated Asymmetric Cycloadditions between Nitrile Oxides and o‐Hydroxystyrenes by Dual Activation. Issue 39 (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 international edition. Volume 56:Issue 39(2017)
• Page Start: 11936
• Page End: 11939
• Publication Date: 2017-08-24
• Subjects: cycloaddition -- density-functional calculations -- heterocycles -- hydrogen bonds -- organocatalysis; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201705662
• Languages: English
• ISSNs: 1433-7851

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. Abstract : Agreeable interactions : The first example of 1, 3‐dipolar cycloadditions between nitrile oxides and o ‐hydroxystyrenes, mediated by a cinchona‐alkaloid‐based amine‐urea catalyst, is reported. The reaction involves the dual activation of both the LUMO of the nitrile oxide and HOMO of the o ‐hydroxystyrene, as confirmed by computational studies. The activation is facilitated by hydrogen‐bonding interactions with the bifunctional catalyst.