Biphenyl dioxygenase-catalysed cis-dihydroxylation of 2-chloroquinoline, 2-chloro-3-methylquinoline and 2-chloro-6-phenylpyridine substrates yielded the corresponding enantiopure cis-dihydrodiols; enantiopure 2,2'-bipyridines, synthesised in four steps from 2-chloroquinoline, proved to be efficient chiral ligands in catalytic asymmetric allylic oxidation and cyclopropanation reactions of alkenes.
The first enantiopure 4,4'-bipyridyls, , , and have been prepared in four or five steps via bacterial dioxygenase-catalysed cis-dihydroxylation of 4-chloroquinoline and C-C coupling; ligands and are found to be effective building blocks for the preparation of chiral metal-organic frameworks as demonstrated with the rational synthesis of two pillared-grid structures [Zn(2)(fumarate)(2)(L)], which exhibit interesting structural and dynamic aspects.
A series of enantiopure 2,2'-bipyridines have been synthesised from the corresponding cis-dihydrodiol metabolites of 2-chloroquinolines. Several of the resulting hydroxylated 2,2'-bipyridines were found to be useful chiral ligands for the asymmetric aminolysis of meso-epoxides leading to the formation of enantioenriched amino alcohols (-->84% ee). N-oxide and N,N'-dioxide derivatives of these 2,2'-bipyridines, including separable atropisomers, have been synthesised and used as enantioselective organocatalysts in the asymmetric allylation of aldehydes to give allylic alcohols (-->86% ee).
The absolute configurations of cis-dihydrodiol bacterial metabolites derived from quinoline substrates and their quinolinium salts have been determined by comparison of experimental and calculated chiroptical data (circular dichroism spectra and optical rotations). The role of intramolecular H-bonding and other interactions in the preferred conformations has been investigated, including the effect of protonation of several cis-dihydrodiols. The presence of a strong intramolecular OHÁÁ ÁN bond in several cis-dihydrodiol metabolites suggests that such species have a residually chiral oxygen atom. Chirality 21:E37-E47, 2009. V
Frameworks. -Enantiopure 4,4'-bipyridyls such as (VII) are prepared via bacterial dioxygenase-catalyzed cis-dihydroxylation of 4-chloroquinoline (I) followed by Suzuki reaction. (VII) is an effective building block for the synthesis of chiral metal-organic frameworks based on pillared-layer topologies. -(SBIRCEA, L.; SHARMA, N. D.; CLEGG, W.; HARRINGTON, R. W.; HORTON, P. N.; HURSTHOUSE, M. B.; APPERLEY, D. C.; BOYD*, D. R.; JAMES, S. L.; Chem. Commun. (Cambridge) 2008, 43, 5538-5540; Sch. Chem. Chem. Eng., Queen's Univ., Belfast BT9 5AG, UK; Eng.) -M. Paetzel 13-134
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