Highly Enantioselective Synthesis of Heteroaromatic Alcohols Catalyzed by Chiral Diaminodiphosphine-Ruthenium(II) Complexes

Chiral diaminodiphosphine-ruthenium(II) complexes were found to be excellent catalysts for the asymmetric transfer hydrogenation of heteroatomic ketones in propan-2-ol. In the presence of potassium hydroxide, the enantioselective reduction of heteroaromatic ketones procceded smoothly to give chiral alcohols with excellent enantiomeric excess (up to 97% ee) under mild conditions without reduction of the heterocycle.National Natural Science Foundation of China [20423002, 20703034]; Natural Science Foundation of Fujian Province of China [2008J0235]; State Key Laboratory of Physical Chemistry of Solid Surface

Assembly of Ag(I) polymers with thioether-S binding and homochiral helices

A novel coordination polymer [Ag(pyta)](n) (pyta(-) = 4-pyridylthioacetate) containing bound thioether sulfurs and single-stranded helical chains has been synthesized and structurally characterized

Highly efficient chiral metal cluster systems derived from Ru-3(CO)(12) and chiral diiminodiphosphines for the asymmetric transfer hydrogenation of ketones

The chiral Ru cluster-based catalyst systems generated in situ from Ru-3(CO)(12) and chiral diiminodiphosphine tetradentate ligands effected asymmetric transfer hydrogenation of propiophenone in 2-propanol, leading to 1-phenyl-1-propanol in 94% yield and with 96% ee

Synthesis and CD spectra of chiral molybdenum-fullerenyl complexes with pineno-bipyridine ligands

The synthesis and characterization of two chiral fullerene complexes (+)(430)(CD)- [Mo(eta(2)-C-60) (CO)(3)(L-RR)] 1and (-) CD430CD-[Mo(eta(2)-C-60)(CO)(3)(L-SS)] 2 were described. The CD spectra of 1 and 2 in the visible range show weak Cotton effects, which are approximately of mirror image, indicating that the appended pineno-groups with opposite chirality in bipyridines can perturb the fullerene chromophores through the molybdenum centers and lead to induced CD effects

Synthesis, characterization and solid-state CD spectra of the chiral bisferrocenyl ligands

A pair of novel chiral tetradentate bisferrocenyl ligands [N,N '-bisferrocenyimethyl-N,N '-bis(2hydroproxypyl)- (1R, 2R)-1,2-diphenylethane-diamine(5R), N,N '-bisferrocenylmethyl-N,N '-bis(2-hydroxypropyl)-(1S, 2S)-1,2-diphenylethane diamine (5S)] were synthesized from ferrocenylcarboxaldehyde (1) and chiral 1,2-diphenylethanediamine (2R or 2S) followed by the reduction of the Schiff bases with NaBH4 and subsequent N-alkylation with 1,2-propyleneoxide. All the chiral products (3R-5S) were charactered by elemental analysis, infrared (IR), H-1 nuclear magnetic resonance (H-1 NMR), ultraviolet-visible (UV-Vis) and solid-state circular dichroism (CD) spectra. The solidstate CD spectra reveal that the chiral characteristics of 5R (or 5S) are quite similar with 4R (or 4S) and it is also notable that there are some differences between 5R (or 5S) and 3R (or 3S)

Novel Chiral PNNP-Ru Complexes: Synthesis and Application in Asymmetric Transfer Hydrogenation of Ketones

The efficient catalytic systems generated in situ from RuCl(2)(PPh(3))(3) and chiral ligands N,N-bis[2-(di-o-tolylphosphino)-benzyl]cyclohexane-1,2-diamine(2) were employed for asymmetric transfer hydrogenation of aromatic ketones, giving the corresponding optically active alcohols with high activities(up to 99% conversion) and excellent enantioselectivities(up to 96% e.e.) undcr mild conditions. The chiral ruthenium(II) complex (R,R)-3 has been prepared and characterized by NMR and X-ray crystallography.National Natural Science Foundation of China[20423002, 20703034]; Natural Science Foundation of Fujian Province of China[2008J0235]; Natural Science Foundation of Guangxi Province of China[0991016

Automatic text clustering via particle swarm optimization

An automatic clustering algorithm based on particle swarm optimization, termed ATCPSO, is proposed for texting clustering in this paper. autoPSO has been exploited for evolving the correct number of clusters and simultaneously identifying clusters and has demonstrated to improve the performance of high-dimensional data clustering. To extend autoPSO to text clustering, a few modifications to the algorithm are necessary, such as the similarity measure, parameter selection and the criterion function. Our experimental results on both ten structured text datasets built from 20 newsgroups as well as four text datasets selected from CLUTO show that the proposed algorithm is able to greatly improve the quality of text clustering compared to four typical clustering algorithms and one competitive subspace clustering method