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Synthetic Approaches to Sterically Hindered N ‐Arylimidazoles through Copper‐Catalyzed Coupling Reactions
Author(s) -
Alcalde Ermitas,
Dinarès Immaculada,
Rodríguez Sandra,
Garcia de Miguel Cristina
Publication year - 2005
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200400453
Subject(s) - chemistry , imidazole , steric effects , benzimidazole , catalysis , combinatorial chemistry , coupling reaction , copper , aryl , stereochemistry , medicinal chemistry , organic chemistry , alkyl
Optimization studies allowed the efficient synthesis of a simple structural motif based on meta ‐bis(1‐imidazolyl)benzenes 1 through copper‐catalyzed coupling of 1,3‐diiodobenzene and imidazole under mild reaction conditions. This protocol was then used to prepare a representative sterically hindered N ‐arylimidazole 2a , the most common structural motif among N ‐heterocyclic carbenes (NHC). Having optimized the main variables governing Cu I ‐catalyzed imidazole N ‐arylation, the first Ullmann‐type synthesis of N ‐mesitylimidazole ( 2a ) is reported. Moreover, the coupling between boronic acids as the aryl donor partners and either imidazole or benzimidazole was examined; in all cases the reactions proceeded in very low yield. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)