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Toward the Robust Synthesis of [ 18 F]F‐DOPA: Quantum Chemical Analysis of S N Ar Cold Fluorination of Diaryl Iodonium Salt by 19 F −
Author(s) -
Oh YoungHo,
Choi Hyoju,
Lee SungSik,
Lee Sungyul
Publication year - 2020
Publication title -
bulletin of the korean chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.237
H-Index - 59
ISSN - 1229-5949
DOI - 10.1002/bkcs.11978
Subject(s) - halogenation , chemistry , gibbs free energy , quantum chemical , salt (chemistry) , product (mathematics) , intramolecular force , organic chemistry , molecule , thermodynamics , physics , geometry , mathematics
Quantum chemical analysis is presented for S N Ar cold fluorination of diaryliodonium salts by 19 F − observed by Wirth et al . [ Eur. J. Org. Chem. 2015 , 625]. We examine the origin of experimentally obtained low yields (0–5%) of fluorination by calculating and comparing the relative Gibbs free energies of pre‐reaction complexes and the Gibbs free energies of activation for fluorination, bromination, and intramolecular cyclization. Focusing on the counter‐anion in diaryliodonium salt, we propose that S N Ar bromination would be the predominant process rather than fluorination, resulting in very small amount of fluorinated product. Discussions are made for possible means of improving the yields in cold fluorination.