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LiTMP Trans‐Metal‐Trapping of Fluorinated Aromatic Molecules: A Comparative Study of Aluminum and Gallium Carbanion Traps
Author(s) -
McLellan Ross,
Uzelac Marina,
Kennedy Alan R.,
Hevia Eva,
Mulvey Robert E.
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201706064
Subject(s) - carbanion , chemistry , aryne , metalation , aryl , reactivity (psychology) , trapping , photochemistry , metal , iodide , medicinal chemistry , computational chemistry , organic chemistry , medicine , ecology , alkyl , alternative medicine , pathology , biology
Fluoroaromatic scaffolds pose a challenge to lithiation due to low stability of lithiated intermediates. Here we apply trans‐metal‐trapping (TMT) to a series of key fluorinated aromatics. In TMT, LiTMP performs the metalation, while an organometallic trap intercepts the emergent carbanion. This study contrasts the trapping abilities of i Bu 2 AlTMP and Ga(CH 2 SiMe 3 ) 3 , structurally mapping their TMT reactions and probing relative stabilities of metalated fluoroaromatic intermediates by NMR studies. Results show the installed Al−C(aryl) bonds are more prone to decomposition by benzyne formation and Li‐F liberation, than the Ga−C(aryl) species. The latter are thus better for onward reactivity as demonstrated in cross‐coupling reactions with benzoyl chloride that produce ketones.