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Abstract: A dimeric salen ligand derived from L-tartaric acid was synthesized through linking two salen units with 1,6-dibromohexane. The corresponding Ti complex was proved to be an efficient catalyst for asymmetric addition of trimethylsilyl cyanide to aldehydes, providing the corresponding optically active trimethylsilyl ether of cyanohydrins with moderate to good enantiomeric excesses and excellent yields under relatively low catalyst loading condition. [Copyright &y& Elsevier]

Abstract: Two new tetradentate ligands derived from salen have been prepared and their titanium complexes are used as chiral catalysts in the enantioselective silylcyanation of aldehydes, which give the silyl ethers of cyanohydrins in moderate to good enantiomeric excesses. [ABSTRACT FROM AUTHOR]

Abstract: Chiral N-oxide salen ligands and their corresponding Al complexes were synthesized. Notably, the catalytic activity and asymmetric induction ability of the bifunctional N-oxide salen-Al for asymmetric cyanosilylation were compared with that of bi-component catalyst system including chiral pyrrolidine salen–Al complex and Ph3PO. Interestingly, introducing N-oxide group in salen unit could enhance the activity and enantioselectivity of bifunctional catalyst without further adding Ph3PO as co-catalyst and inverse configurations were generated from the two systems. In addition, excellent yields and high ee values could be obtained under milder conditions in bifunctional catalyst system compared with that of bi-component catalyst system. [Copyright &y& Elsevier]

A series of copper(II) complexes, [CuCl 2 (HL 1 )]·CH 3 OH ( 1 ), [CuL 2 (ONO 2 )] ( 2 ), [CuBrL 2 ] ( 3 ) and [CuL 3 (NCS)(CH 3 OH)] ( 4 ) were prepared from 3,5-dihydroxy- N ′-(pyridin-2-ylmethylene)benzohydrazide (HL 1 ), 2-hydroxy- N ′-(1-(pyridin-2-yl)ethylidene)benzohydrazide (HL 2 ) and 4-methoxy- N ′-(pyridin-2-ylmethylene)benzohydrazide (HL 3 ). The compounds were characterized by physico-chemical methods. Structures of HL 1 and the complexes were further confirmed by single crystal X-ray diffraction. The metal atoms in complexes 1 and 4 display square pyramidal coordination, in complexes 2 and 3 display square planar coordination. The inhibitory effects of the compounds on Jack bean urease were evaluated. The results showed that the hydrazone HL 1 and complexes 1 and 4 have significant urease inhibitory activities, with IC 50 values of 8.2 ± 1.5, 6.3 ± 1.7, and 3.1 ± 1.2 μmol·L −1 , respectively. Complexes 2 and 3 show medium urease inhibitory activities, with IC 50 values of 35.7 ± 3.1, and 41.5 ± 2.7 μmol·L −1 , respectively. Molecular docking study of the compounds with Jack bean urease was performed to study the probable binding modes. The compounds with effective urease inhibitory activities anchor well in the active center of the urease and extend to the entrance of the binding pocket by interacting with its key amino acid residues. The results endorse that the hydrazone compound HL 1 and complexes 1 and 4 may serve as structural templates for the design and development of novel urease inhibitors. [ABSTRACT FROM AUTHOR]

Urease inhibitors can counteract the negative effects of urease. In this paper, three new copper(II) complexes derived from 3-methyl- N ′-(pyridin-2-ylmethylene)benzohydrazide (HL) were prepared. They are [CuBr(CH 3 OH)L] ( 1 ), [Cu(CH 3 OH)L(NCS)] ( 2 ), and [CuL(HL)]·ClO 4 ( 3 ). The complexes were characterized by infrared and UV–Vis spectra, and single crystal X-ray determination. The Cu atoms in complexes 1 and 2 display square pyramidal coordination, and in complex 3 the Cu atom displays octahedral coordination. Complex 1 shows effective urease inhibitory activity, with IC 50 value of 1.46 ± 0.83 μM. Molecular docking study of the complexes with Jack bean urease was performed. [ABSTRACT FROM AUTHOR]