Brønsted Acid Promoted Reactions of γ-Hydroxy Acetylene Ketones. DFT Study of Cationic Intermediates and Concurrent Formation of 3-Furanones and/or Conjugated Enynones

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发表日期：

2024年1月1日

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A. A. Kuzmin,
I. A. Boyarskaya,
O. V. Khoroshilova,
M. V. Kalyaev,
A. V. Vasilyev

摘要

Abstract

Protonation of γ-hydroxy conjugated acetylene ketones Ph(O=)C–C≡C–C(OH)R¹R² in strong Brønsted acid H₂SO₄ or superacid TfOH (CF₃SO₃H, triflic acid) gives rise to O,O-diprotonated species Ph(⁺HO=)C–C≡C–C(OH₂⁺)R¹R². Electrophilic, electronic and orbital properties of these dications have been studied by DFT calculations. Depending on the structure of the dications and acidity of Brønsted acid (nucleophilicity of the corresponding acid counter ion), two concurrent reaction products may be formed, 3(2H)-furanones in a way of cyclization and/or conjugated enynones in a way of dehydration. Plausible reaction mechanisms are discussed.