Asymmetric synthesis of chiral bisoxazolines and their use as ligands in metal catalysis

Recent advances in the asymmetric reduction of imines by recycled catalyst systems

Recent advances relating to the asymmetric reduction of imines to afford optically active amines via recyclable catalyst systems are reviewed.

The first 4,4′-imidazolium-tagged C2-symmetric bis(oxazolines): application in the asymmetric Henry reaction

Highly efficient and recyclable imidazolium-tagged bis(oxazolines), with an imidazolium tagged onto the 4,4′-position of the box, have been designed and prepared for the first time.

Synthesis and characterization of some new C2 symmetric chiral bisamide ligands derived from chiral Feist's acid

The hemilabile chiral C2 symmetrical bidentate substituted amide ligands (1R,2R)-5(a-d) and (1S,2S)-6(a-d) were synthesized in quantitative yield from (1R,2R)-(+)-3-methylenecyclo-propane-1,2-dicarboxylic acid (1R,2R)-3 and (1S,2S)-(-)-3-methylene-cyclopropane-1,2-dicarboxylic acid (1S,2S)-3, in two steps, respectively. The chiral Feist's acids (1R,2R)-3 and (1S,2S)-3 were obtained in good isomeric purity by resolution of trans-(±)-3-methylene-cyclopropane-1,2-dicarboxylic acid from an 8:2 mixture of tert-butanol and water, using (R)-(+)-α-methylbenzyl amine as a chiral reagent. This process is reproducible on a large scale. All these new synthesized chiral ligands were characterized by 1H-NMR, 13C-NMR, IR, and mass spectrometry, as well as elemental analysis and their specific rotations were measured. These new classes of C2 symmetric chiral bisamide ligands could be of special interest in asymmetric transformations.

Recent advances in enantioselective organocatalyzed anhydride desymmetrization and its application to the synthesis of valuable enantiopure compounds

Recent years have witnessed increasing interest in the field of asymmetric organocatalysis. In particular, efforts in this field have been devoted to the use of small organic molecules in asymmetric processes based on enantiotopic face discrimination and, only recently, efforts have also been devoted to asymmetric organocatalytic desymmetrization of prochiral substrates-a process based on enantiotopic group discrimination. This critical review documents the advances in the use of organocatalysis for the enantioselective desymmetrization of achiral and meso anhydrides and its application to the synthesis of valuable compounds as reported until 2010 (134 references).

An Efficient Diastereoselective Route to Differentially Protected anti-4-Amino-1-alken-3-ols

Zinc-promoted hydroxyallylation of alpha-amidoalkyl arylsulfones 4 using 3-bromo-propenyl methyl carbonate 5 proceeds smoothly in DMF at room temperature to afford high yields of differentially protected anti-1,2-amino alcohols 6.

The application of bis(oxazoline) ligands in the catalytic enantioselective methallylation of aldehydes

A series of symmetric and non-symmetric bis(oxazoline) ligands were applied in the Nozaki-Hiyama-Kishi methallylation of a range of aromatic and aliphatic aldehydes. A non-symmetrical ligand with tert-butyl/benzyl-substituted oxazolines provided the highest enantioselectivity of 99.5% for the methallylation of benzaldehyde.