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A Practical Transition Metal‐Free Aryl‐Aryl Coupling Method: Arynes as Key Intermediates
Author(s) -
Leroux Frédéric R.,
Bonnafoux Laurence,
Heiss Christophe,
Colobert Françoise,
Lanfranchi Don Antoine
Publication year - 2007
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200700211
Subject(s) - chemistry , aryne , iodobenzene , aryl , combinatorial chemistry , regioselectivity , bromine , halogen , nucleophile , halide , transition metal , nucleophilic aromatic substitution , lithium (medication) , nucleophilic substitution , organic chemistry , catalysis , medicine , alkyl , endocrinology
Upon treatment of various aryllithium intermediates with 1,2‐dibromobenzene or 1‐bromo‐2‐iodobenzene, dissymmetrical ortho,ortho′ ‐di‐, tri‐ and even tetrasubstituted bromo‐ or iodobiaryls become readily available. The crucial steps in all these reactions were the nucleophilic addition of the organolithium precursor to a transient aryne species released from it by β‐elimination of a lithium halide and, stabilization of the resulting 2‐biaryllithium intermediate by in situ transfer of bromine or iodine from the starting material. This straightforward transition metal‐free access to biaryls allows the preparation of highly valuable halobiaryls on a gram scale in excellent yields. These precursors can be subsequently functionalized by highly regioselective halogen/metal permutations into a vast variety of target molecules. This was demonstrated in the synthesis of several mono‐ and diphosphine ligands.