Stabilization of sp-Hybridized Nitrogen Cation by Lewis Acid-Base Complex Formation with Intramolecular Iodine.

Autor: Fujino T; Department of Organic and Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan., Hyodo T; Faculty of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan., Otani Y; Department of Organic and Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan., Yamaguchi K; Faculty of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa, 769-2193, Japan., Ohwada T; Department of Organic and Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Jazyk: angličtina
Zdroj: Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2024 Jan 22; Vol. 30 (5), pp. e202303393. Date of Electronic Publication: 2023 Nov 29.
DOI: 10.1002/chem.202303393
Abstrakt: Here we show that the sp-hybridized nitrogen cation is strongly stabilized by a peri-iodine substituent in the tetralone system. The cation is captured by anionic species such as CF 3 CO 2 - , affording hypervalent iodine(III) compounds with a short nitrogen-iodine (N-I) bond, in which the cation serves as a Lewis acid. Notably, the O-I bond of the O-trifluoroacetate or O-acetate is intrinsically weaker than the N-I bond due to its more ionic character and is further weakened by protonation in trifluoroacetic acid. As a result, the oxygen ligand can dissociate in the presence of a Brønsted acid, affording a I + cation intermediate that retains the N-I bond. We isolated the cation as the tetrafluoroborate, and characterized it experimentally by 1 H NMR spectroscopy and X-ray structure analysis, and theoretically by means of DFT calculation. The results suggest that the N-I bonded cation is intrinsically stable, and is weakly coordinated with water and the BF 4 counter anion or trifluoroacetate anion. This cation can be employed as a reagent for α-oxidation of ketones.
(© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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