Halogen Bonding of N-Halosuccinimides with Amines and Effects of Brønsted Acids in Quinuclidine-Catalyzed Halocyclizations

Li, Jing, Kwon, Eunsang, Lear, Martin and Hayashi, Yujiro (2021) Halogen Bonding of N-Halosuccinimides with Amines and Effects of Brønsted Acids in Quinuclidine-Catalyzed Halocyclizations. Helvetica Chimica Acta, 104 (9). e2100080. ISSN 0018-019X

Full content URL: https://doi.org/10.1002/hlca.202100080

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Halogen Bonding of N-Halosuccinimides with Amines and Effects of Brønsted Acids in Quinuclidine-Catalyzed Halocyclizations
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Abstract

An arguable expectation in halogen chemistry is that an amine will react oxidatively with an N-halosuccinimide (NXS) to form an N-halogenated species bearing a covalent N−X bond. While likely for NCS under most conditions, we find this expectation simply not true for NIS and largely inaccurate for NBS. Herein, we disclose evidence through systematic NMR and X-ray studies that non-covalent halogen bonded amine complexes of NIS predominate over covalent N-halogenated species, even with primary and secondary amines. For example, during the catalytic electrophilic halocyclization of gem-disubstituted alkenes by cinchona-like amines, the quinuclidine complexes of NIS and NBS display lower reactivity than their parent N-halosuccinamides and require the presence of an appropriate Brønsted acid. Specifically, a Brønsted acid and quinuclidine jointly catalyze the halo-cycloetherification of γ-alkenyl alcohols with NIS or NBS, while only quinuclidine acts as a catalyst in the halolactonization of γ-alkenoic acids. Although our evidence confirms a transient N-halogenated quaternary ammonium salt as the halonium species, it is important to note that NIS predominantly forms ‘off-cycle’ halogen bonded amine complexes in solution.

Keywords:halogen bonding, halogen interactions, catalysis, organocatalysis
Subjects:F Physical Sciences > F160 Organic Chemistry
F Physical Sciences > F100 Chemistry
Divisions:College of Science > School of Chemistry
ID Code:45834
Deposited On:16 Aug 2021 12:25

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