Achiral and α-Amino Acid Derived Dicationic Imidazoliophanes
作者:Filip Bureš、Aleš Marek、Jiří Kulhánek、W. Schweizer
DOI:10.1055/s-0030-1258183
日期:2010.9
Achiral and chiral imidazoliophanes were prepared by N-alkylation of chiral imidazole derivatives featuring an α-amino acid motif and subsequent double quarternization of the imidazole N3-position of the corresponding precyclophanes. Eight new optically pure imidazoliophanes were synthesized in good yields, whereas the molecular structure of one achiral analogue was confirmed by X-ray analysis.
Design and Efficient Synthesis of Amino Acid Derived 2-Substituted Imidazoles by Palladium-Catalyzed Cross-Coupling Reactions
作者:Filip Bureš、Aleš Marek、Jiří Kulhánek
DOI:10.1055/s-0028-1083263
日期:2009.1
Optically active imidazole derivatives featuring an α-amino acid motif substituted at the 2-position can be prepared in moderate to good yields by Negishi as well as Suzuki-Miyaura cross-couplings as the key synthetic steps. The reaction sequence involves N-protection (ethoxymethylation), whereby both generated regioisomers could be separated by column chromatography, and selective 2-lithiation. Subsequent transmetalation to zinc or an iodine quench affords reactants suitable for Pd-catalyzed Negishi and Suzuki-Miyaura reactions with (hetero)aromatics.