139975-85-2Relevant academic research and scientific papers
Regioselective C-H alkenylation of imidazoles and its application to the synthesis of unsymmetrically substituted benzimidazoles
Kim, Hyeongwoo,Hwang, Ye Ji,Han, Inhyuk,Joo, Jung Min
supporting information, p. 6879 - 6882 (2018/06/26)
A palladium-catalyzed C-H alkenylation of imidazoles has been developed. High C5 selectivity was achieved for C2-unsubstituted and C2-substituted imidazoles using oxygen and copper(ii) acetate, respectively, as oxidants. The obtained products were applied
C-H bonds as ubiquitous functionality: A general approach to complex arylated imidazoles via regioselective sequential arylation of all three C-H bonds and regioselective n -alkylation enabled by SEM-group transposition
Joo, Jung Min,Toure, B. Barry,Sames, Dalibor
supporting information; experimental part, p. 4911 - 4920 (2010/10/21)
(Figure presented) Imidazoles are an important group of the azole family of heterocycles frequently found in pharmaceuticals, drug candidates, ligands for transition metal catalysts, and other molecular functional materials. Owing to their wide application in academia and industry, new methods and strategies for the generation of functionalized imidazole derivatives are in demand. We here describe a general and comprehensive approach for the synthesis of complex aryl imidazoles, where all three C-H bonds of the imidazole core can be arylated in a regioselective and sequential manner. We report new catalytic methods for selective C5- and C2-arylation of SEM-imidazoles and provide a mechanistic hypothesis for the observed positional selectivity based on electronic properties of C-H bonds and the heterocyclic ring. Importantly, aryl bromides and low-cost aryl chlorides can be used as arene donors under practical laboratory conditions. To circumvent the low reactivity of the C-4 position, we developed the SEM-switch that transfers the SEM-group from N-1 to N-3 nitrogen and thus enables preparation of 4-arylimidazoles and sequential C4-C5-arylation of the imidazole core. Furthermore, selective N3-alkylation followed by the SEM-group deprotection (trans-N-alkylation) allows for regioselective N-alkylation of complex imidazoles. The sequential C-arylation enabled by the SEM-switch allowed us to produce a variety of mono-, di-, and triarylimidazoles using diverse bromo- and chloroarenes. Using our approach, the synthesis of individual compounds or libraries of analogues can begin from either the parent imidazole or a substituted imidazole, providing rapid access to complex imidazole structures.
Catalytic C-H arylation of SEM-protected azoles with palladium complexes of NHCs and phosphines
Toure, B. Barry,Lane, Benjamin S.,Sames, Dalibor
, p. 1979 - 1982 (2007/10/03)
The synthesis and catalytic evaluation of palladium complexes containing imidazolyl carbene ligand of varying steric and electronic properties is reported. These complexes catalyze the efficient C-H arylation of SEM-protected azole heteroarenes and thus provide a good method for preparation of a wide range of arylated free (NH)-azoles including pyrroles, indoles, imidazoles, and imidazo[1,2-a]pyridines. The reaction is operationally simple; the complexes are insensitive to moisture.
New Synthetic Applications of Vinyliminophosphoranes Based on the Reactivity of the Vinyl Side Chain
Molina, Pedro,Aller, Enrique,Lopez-Lazaro, Antonia,Alajarin, Mateo,Lorenzo, Angeles
, p. 3817 - 3820 (2007/10/02)
New reactions of vinyliminophosphoranes involving either the β-carbon atom of the vinyl side chain as nucleophilic center or the α-carbon as electrophilic center are described
