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(Hetero)Arylation of 6‐Halogenoimidazo[1,2‐ a ]pyridines Differently Substituted at C(2): Influence of the 2‐Substituent on the Suzuki Cross‐Coupling Reaction
Author(s) -
Enguehard Cécile,
Hervet Maud,
Théry Isabelle,
Renou JeanLouis,
Fauvelle Florence,
Gueiffier Alain
Publication year - 2001
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20011219)84:12<3610::aid-hlca3610>3.0.co;2-d
Subject(s) - chemistry , substituent , reactivity (psychology) , aryl , suzuki reaction , medicinal chemistry , coupling reaction , boronic acid , halogen , alkyl , catalysis , stereochemistry , organic chemistry , medicine , alternative medicine , pathology
We previously reported that reactivity towards the Suzuki cross‐coupling reaction of 3‐iodoimidazo[1,2‐ a ]pyridines substituted at C(2) is largely influenced by the nature of this 2‐substituent. Hence, with the aim to expand the scope of this coupling process to the 6‐position of this series, it seemed important to similarly determine the influence of the nature of the 2‐substituent (H, alkyl, or aryl) on the rate of coupling. From this work, the Suzuki ‐type cross‐coupling was shown to proceed efficiently on 6‐bromo‐2‐methyl‐ and 2‐(4‐fluorophenyl)imidazo[1,2‐ a ]pyridines, whereas the 6‐Br derivative unsubstituted at C(2) appeared to be poorly reactive. By modifying the reaction conditions in terms of catalyst and base, and the nature of the halogen, the reactivity of the unsubstituted series was largely enhanced. Finally, this work led us to establish efficient and convenient Suzuki reaction conditions for the 6‐(hetero)arylation of 6‐halogenoimidazo[1,2‐ a ]pyridines depending on the nature of the 2‐substituent and boronic acid.