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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 - 2006
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.200600338
Subject(s) - chemistry , steric effects , catalysis , copper , coupling reaction , combinatorial chemistry , coupling (piping) , organic chemistry , mechanical engineering , engineering
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 CuI-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)