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Stille Cross‐Coupling for the Functionalization of the Imidazole Backbone: Revisit, Improvement, and Applications of the Method
Author(s) -
Sandtorv Alexander H.,
Törnroos Karl Wilhelm,
Bjørsvik HansRené
Publication year - 2015
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.201500328
Subject(s) - stille reaction , chemistry , imidazole , surface modification , sulfonyl , combinatorial chemistry , coupling reaction , ring (chemistry) , context (archaeology) , coupling (piping) , stereochemistry , computational chemistry , catalysis , organic chemistry , materials science , paleontology , alkyl , metallurgy , biology
We have revisited the Stille coupling reaction for the functionalization of the imidazole backbone. In this context Cu I was exploited as a co‐catalyst, which resulted in significantly improved yields of target coupling products. Furthermore, a systematic investigation of the effect of the auxiliary group on the N ‐1‐ring atom was performed. When mono‐coupling is desired, the Tosyl (Tos) group is superior to the (dimethylamino)sulfonyl (DMAS) group, furnishing the corresponding 4‐coupled imidazoles in significantly higher yields. However, when bis‐coupling is preferred, the DMAS group is imperative for success of the coupling procedure. Utilizing this reaction protocol, we were successfully able to demonstrate the first examples of Stille bis‐coupling utilizing N ‐DMAS‐4,5‐diiodoimidazole as substrate.