- SupraBox: Chiral supramolecular oxazoline ligands
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A new class of oxazoline ligands, named SupraBox, was studied. These ligands possess an additional urea functionality to generate supramolecular bidentate ligands in transition-metal complexes, by the establishment of hydrogen bonds between the urea N-hydrogens of one ligand and the carbonyl oxygen of a second one. A library of 16 SupraBox ligands was prepared using 5 differently substituted oxazoline nuclei, 4 linkers and 3 different urea substituents. The formation of copper(II) and palladium(II) complexes was investigated by MS, UV/Vis and 1H-NMR spectroscopy. The SupraBox library was screened in the copper-catalyzed asymmetric benzoylation of vic-diols. Good selectivities were obtained in the kinetic resolution of racemic hydrobenzoin [up to 86 % ee and selectivity (s) = 28] and in the desymmetrization of meso-hydrobenzoin (up to 88 % ee).
- Durini, Marco,Russotto, Eleonora,Pignataro, Luca,Reiser, Oliver,Piarulli, Umberto
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p. 5451 - 5461
(2012/10/30)
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- NITROSATION OF N'-SUBSTITUTED 3- AND 4-UREIDOALKANOIC ACIDS
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The nitrosation of N'-substituted 3- and 4-ureidoalkanoic acids, synthesized by the condensation of 3- and 4-aminoalkanoic acids with hexyl- and phenyl isocyanates, was studied under various conditions.The ratios of the obtained N- and N'-nitroso derivatives were established by PMR spectroscopy.
- Lutsenko, V. V.,Klimavichyus, K.-A. V.
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p. 1905 - 1908
(2007/10/02)
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