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PREPARATION AND SOME APPLICATIONS OF ENANTIOPURE IMIDAZOLE DERIVATIVES IN ASYMMMETRIC CATALYSIS
Authors: Mloston Grzegorz | Wróblewska Aneta | Tydlitát Jiří | Bureš Filip
Year: 2012
Type of publication: ostatní - přednáška nebo poster
Page from-to: nestránkováno
Titles:
Language Name Abstract Keywords
eng PREPARATION AND SOME APPLICATIONS OF ENANTIOPURE IMIDAZOLE DERIVATIVES IN ASYMMMETRIC CATALYSIS Optically active imidazoles and its saturated analogues (imidazolines, imidazolidines) are relatively little known as organocatalysts or ligands for asymmetric catalysis [1]. Due to our ongoing interest in the chemistry of optically active, five membered N-heterocycles [2], we elaborated an efficient method for preparation of enantiopure imidazole derivatives 2-6 starting with N-benzylated (S)-prolinamine (1) as a chirality platform [3]. Both, imidazole N-oxides 2 and imidazoles 3, upon treatment with alkyl bromides, underwent alkylation yielding the imidazolium salts, exclusively. After Br → BF4 anion exchange, new optically active room temperature ionic liquids (RTIL’s) 5 and 6 were obtained [3]. All of the reported compounds 2-6 are potentially useful as the new, (S)-proline based ligands for asymmetric catalysis and related applications. In addition, synthesis of a series of the regioisomeric, enantiopure imidazolines 8 and 9 from (1R,2S,3R)-camphor-2,3-diamine dihydrochloride (7) via Pinner reaction and subsequent functionalization of the NH-position, will also be presented [4]. After chromatographic separation, imidazolines 8 and 9 were tested as ligands in asymmetric Henry reaction using p-nitrobenzaldehyde and nitromethane. In the series of the performed experiments, chemical yields up to 94% and ee values up to 60% were obtained [4]. imidazole; asymmetric catalysis; ligand