The concept of utilizing the methods of directed evolution for tuning the enantioselectivity of synthetic achiral metal-ligand centers anchored to proteins has been implemented experimentally for the first time.

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Synthesis of chiral diphosphine ligands containing a spiro scaffold was described. The ruthenium complexes of these spiro ligands were found to have extremely high activities (S/C up to 100 000) and enantioselectivities (ee up to 99.5%) in the asymmetric hydrogenation of aromatic, heteroaromatic, and alpha,beta-unsaturated ketones.

Optically active a-arylalkylamines are an important class of compounds that are widely used in organic and pharmaceutical synthesis, and much effort has been made to develop efficient asymmetric synthetic methods for them. [1] Asymmetric catalytic hydrogenation of enamides, initiated by Kagan et al., [2] provides a direct and convenient route to chiral amine derivatives. However, many well-known chiral diphosphane ligands, such as DIOP, BINAP, and CHIRA-PHOS, which are extremely successful in the asymmetric hydrogenation of dehydroamino acid derivatives, do not give high enantioselectivity in the hydrogenation of enamides. [3,4] A breakthrough was achieved by Burk et al. [4a] with the introduction of BPE and DuPHOS ligands, which gave excellent enantioselectivity in the Rh-catalyzed asymmetric hydrogenation of enamides. Lately, some other P ligands were also reported to be efficient in the hydrogenation of enamides. [4b, 5] However, all ligands that gave a high degree of enantiocontrol are bidentate. To our knowledge, no efficient chiral monodentate ligand has been reported for the asymmetric hydrogenation of enamides, although some monodentate P ligands were successfully used in the hydrogenation of dehydroamino acid derivatives. [6] Here we describe highly efficient monodentate chiral ligands 1 containing a 1,1'-spirobiindane backbone for the Rh-catalyzed asymmetric hydrogenation of a-arylethenylamine derivatives [Eq. (1)] with excellent enantioselectivities (up to 99.7 % ee).The chiral monodentate phosphoramidite ligands 1 (abbreviated SIPHOS) were conveniently synthesized in good yields from enantiomerically pure 1,1'-spirobiindane-7,7'-diol, which was easily prepared from 3-methoxybenzaldehyde by using the procedure described by Birman et al. [7] We demonstrated recently that the Rh complex of (S)-1 a (R CH 3 ) is a highly efficient catalyst in the asymmetric hydrogenation of dehydroamino acid and itaconic acid derivatives with up to 99.3 % ee. Therefore, we were prompted to investigate the utility of this catalyst in the asymmetric hydrogenation of a-phenylenamide 4 a and an excellent enantioselectivity (up to 98.8 % ee) was achieved. This showed, for the first time, that monodentate phosphorus ligands can be effective in the enantiocontrol of asymmetric hydrogenation of enamides.The results in Table 1 show that the enantioselectivity of the reaction was sensitive to the solvent used, and toluene is the solvent of choice. In contrast, the hydrogen pressure has a negligible influence on the enantioselectivity. For example, in the hydrogenation of 4 a with Rh/(S)-1 a catalyst in toluene, the ee values of product 5 a at 25 8C under 10 atm and 100 atm H 2 were 96 % and 96.2 %, respectively (Table 1, entries 1 and 2). The investigation of catalyst loading showed that 0.5 mol % catalyst was sufficient to give a high enantioselectivity, while the ee value of the product dropped drastically with 0.1 mol % catalyst.Catalysts prepared in situ from cationic Rh complexes were active in the asymmetric hydrogenation...

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To investigate the effects of Clostridium butyricum on growth performance, antioxidation, and immune function of broilers, 320 one-day-old Arbor Acres commercial male chicks were assigned to one of 5 treatments with 8 replicates in a completely randomized design for 42 d. The 5 treatments were basal diet (control), basal diet supplemented with 2.5×10(8) cfu C. butyricum/kg (CB1), basal diet supplemented with 5×10(8) cfu C. butyricum/kg (CB2), basal diet supplemented with 1×10(9) cfu C. butyricum/kg (CB3), and basal diet supplemented with 150 mg aureomycin/kg (antibiotic). The results showed that all C. butyricum-supplemented groups during d 1 to 21 and the CB2 group during d 22 to 42 had higher ADG compared with the control (P<0.05). Chicks fed the CB3 diet had higher glutathione S-transferase (GST) activity (P<0.05), and chicks fed the CB2 diet had a higher glutathione (GSH) concentration in duodenal and ileal mucosa at 21 d of age than those in the control group (P<0.05). Chicks fed the CB3 diet had a lower malondialdehyde (MDA) concentration in duodenal mucosa than those in the control and CB1 groups (P<0.05). Chicks fed the CB2, CB3, and antibiotic diets had a lower MDA concentration in ileal mucosa than those in the control and CB1 groups (P<0.05). Broilers fed the CB3 diet had greater superoxide dismutase (SOD) activity in the ileal mucosa on d 21 and in jejunal mucosa on d 42 than those in the other groups (P<0.05). Chicks fed the CB2, CB3, and antibiotic diets had a higher GSH concentration in duodenal and jejunal mucosa on d 42 than those in the control group (P<0.05). Broilers fed the CB2 and CB3 diets had a lower MDA concentration in the jejunal mucosa on d 42 than those in the control and CB1 groups. Chicks fed diets supplemented with C. butyricum had a higher IgM concentration than those in the control group at 21 and 42 d of age (P<0.05). The results indicate that C. butyricum improves broilers' growth performance, antioxidation, and immune function.

Combined IVIM and ASL MRI can better evaluate the diffusion and perfusion properties for allografts early after kidney transplantation.

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