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Abstract: The catalytic enantioselective Michael additions of cyclic β-ketoamides to nitroolefins and alkynones were accomplished in the presence of chiral N,N′-dioxide–Co(II) complexes. The desired adducts were obtained in high yields (up to 98%) with excellent enantioselectivities (up to 97%ee). [Copyright &y& Elsevier]

Abstract: A novel C 2-symmetric chiral N,N′-dioxide titanium complex was described, which could efficiently catalyze the asymmetric cyanosilylation of ketones in high yields with up to 92% ee under mild conditions. In addition, the catalyst system was simple and the ligands could be easily prepared from commercially available chiral amino acid. [Copyright &y& Elsevier]

A racemic N,N ′-dioxide-iron(III) complex was first found to be an efficient chemosensor for simultaneous determination of the absolute configuration, concentration, and enantiomeric excess (ee) of hydroxy carboxylic acids in aqueous solution via circular dichroism (CD) and fluorescence. The accuracy of the ee measurement is very good, within 3%. And the analysis is fast, eliminating laborious derivatization and elaborating purification steps. [ABSTRACT FROM AUTHOR]

Abstract: A chiral fluorescent sensor (Ra,S,l)-3 incorporating (R)-BINOL and l-prolinamide is found efficient in enantioselective recognition of N-Cbz-protected phenylglycine. It is observed that one enantiomer of N-Cbz-protected phenylglycine can obviously increase the fluorescence intensity of (Ra,S,l)-3, while the other enantiomer does not cause much fluorescence enhancement. Such highly enantioselective response makes the sensor (Ra,S,l)-3 useful for the enantioselective fluorescence recognition of other N-Cbz-protected amino acids. [Copyright &y& Elsevier]

Abstract: A direct asymmetric Michael addition of cyclic 1,3-dicarbonyl compounds to β,γ-unsaturated α-ketoesters could be efficiently catalyzed by an N,N′-dioxide–nickel(II) complex. A series of chiral warfarin derivatives were obtained in excellent yields (up to 99%) with high enantioselectivities (up to 90% ee) under mild conditions within shorter reaction time. [Copyright &y& Elsevier]

Abstract: Chiral N,N′-dioxide-Ytterbium(III) complexes promoted the asymmetric addition of diethyl phosphate to aldehydes, giving the corresponding products with good yields and enantioselectivities. The addition of pyridine favored both reactivity and enantioselectivity. A possible catalytic cycle was proposed to explain the mechanism of the asymmetric hydrophosphonylation of aldehydes. [Copyright &y& Elsevier]

Abstract: The chiral N,N′-dioxide–Yb(OTf)3 complex-catalyzed enantioselective aza-Diels–Alder reaction of Brassard’s diene with aldimines has been developed, giving the corresponding α,β-unsaturated δ-lactam derivatives in moderate yields with good enantioselectivities (up to 81% ee and up to 99% ee by single recrystallization) under mild conditions. Isolation of the reaction intermediate indicates that this asymmetric aza-Diels–Alder reaction proceeds through a stepwise Mannich-type pathway. [Copyright &y& Elsevier]

Abstract: A highly enantioselective fluorescent sensor, containing benzylaminomethyl groups at 3,3′-position of 1,1′-bi-2-naphthol (BINOL), has been used to conduct the chiral recognition of α-amino acid derivatives. It is observed that one enantiomer of N-Boc-proline can increase the fluorescence intensity of the binaphthyl fluorophores by over 57-fold, while the other enantiomer can cause only sixfold fluorescence enhancement. Such unusually highly enantioselective response demonstrates that this sensor is potentially useful in the enantioselective recognition of amino acid derivatives. [Copyright &y& Elsevier]

Abstract: The enantioselective oxa-Michael addition reaction of 1-(4-methoxyphenyl) ethanone oxime to various α,β-unsaturated aldehydes was accomplished by using chiral N,N′-dioxide-FeSO4·7H2O (1:1) complex. Aromatic acid was employed as additive to increase the yield of the reaction. The corresponding adducts were obtained in moderate yields with up to 76% ee under mild conditions. [Copyright &y& Elsevier]

Abstract: 1,1,3,3-Tetramethylguanidine acts as a highly effective catalyst for cyanosilylation of various ketones and aldehydes to the corresponding cyanohydrin trimethylsilyl ethers in up to 99% yield. The reaction proceeds smoothly with 0.1mol% catalyst loading at 25°C under solvent-free conditions. [Copyright &y& Elsevier]

Abstract: A good chiral discrimination of lansoprazole (LAN) enantiomers was realized by a chiral N,N′-dioxide–Sc(III) complex, which was based on a fluorescent method through an ‘off-on’ process. The chiral ligand, N,N′-dioxide, coordinated with scandium(III) triflate forming an organic–metal complex as a chiral selector. Then the LAN enantiomers reacted with the selector and generated different signals in fluorescence. A distinct enantiomeric difference was observed with good repeatability, low detection limit, good linear range, and highly enantiomeric selectivity. At last, this study had offered a quantitative measurement of the enantiomer composition. [Copyright &y& Elsevier]

Abstract: Enantioselective trifluoromethylation of aromatic ketones promoted by the cinchona alkaloid-derived ammonium bromide and sodium hydride was described. A series of trifluoromethyl-substituted aryl alcohols could be obtained in up to 82% ee with 98% yield under mild conditions. A possible catalytic cycle was also presented. [Copyright &y& Elsevier]