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6 results on '"Qinqin Qian"'

1. Asymmetric Michael addition of malonates to unsaturated ketones catalyzed by rare earth metal complexes bearing phenoxy functionalized chiral diphenylprolinolate ligands

Author

Bei Zhao, Chengrong Lu, Yingming Yao, Wenguo Zhu, and Qinqin Qian

Subjects
010405 organic chemistry, Ligand, Stereochemistry, Organic Chemistry, Rare earth, 010402 general chemistry, 01 natural sciences, Medicinal chemistry, Catalysis, 0104 chemical sciences, Prolinol, Inorganic Chemistry, Metal, chemistry.chemical_compound, chemistry, visual_art, Yield (chemistry), Michael reaction, visual_art.visual_art_medium, Phenol, Physical and Theoretical Chemistry
Abstract

A simple, efficient catalytic asymmetric Michael addition of malonates to unsaturated ketones has been successfully developed. This process was promoted by rare earth metal complexes 1–4 bearing a chiral phenoxy functionalized prolinol ligand at room temperature [L1RE(L1H) (H2L1 = (S)-2,4-di-tert-butyl-6-((2-(hydroxydiphenylmethyl)pyrrolidin-1-yl)methyl)phenol, RE = Yb 1, Y 2, Sc 3 and L2Sc(L2H) 4 (H2L2 = (S)-2,4-di-dimethylbenzyl-6-((2-(hydroxydiphenylmethyl)-pyrrolidin-1-yl)methyl)phenol)]. Complex 3 was the best catalyst in the transformation and the products were obtained in up to 99% yield and with 90% ee. In addition, the molecular structures of the catalysts were well characterized, including X-ray determination of complex 3.

Published
2016

2. Synthesis and characterization of ytterbium guanidinates stabilized by bridged bis(phenolate) ligand and their application for the hydrophosphonylation reaction of aldehydes

Author

Yaorong Wang, Qinqin Qian, Qi Shen, Tinghua Zeng, and Yingming Yao

Subjects
Ytterbium, chemistry.chemical_classification, Ligand, Organic Chemistry, chemistry.chemical_element, Infrared spectroscopy, Biochemistry, Medicinal chemistry, Aldehyde, Catalysis, Inorganic Chemistry, chemistry, Octahedron, Materials Chemistry, Salt metathesis reaction, Physical and Theoretical Chemistry, Coordination geometry
Abstract

A series of ytterbium guanidinato complexes stabilized by an amine-bridged bis(phenolate) ligand were prepared, and their catalytic property for the hydrophosphonylation reaction of aldehydes was explored. Metathesis reactions of amine-bridged bis(phenolate) ytterbium chlorides LYbCl(THF) [L = Me 2 NCH 2 CH 2 N{CH 2 -(2-OC 6 H 2 t Bu 2 -3,5)} 2 ] with corresponding lithium guanidinates in a 1:1 molar ratio in THF gave the expected ytterbium guanidinato complexes LYb[R 2 NC(NR 1 ) 2 ] [R 1 = Cy, R 2 N = N(TMS) 2 ( 1 ), N(CH 2 ) 5 ( 2 ); R 1 = i Pr, R 2 N = N(TMS) 2 ( 3 ), NPh 2 ( 4 )]. These ytterbium complexes were well characterized by elemental analyses, IR spectroscopy and single-crystal X-ray structure determination. The metal ion is six-coordinated by two oxygen and two nitrogen atoms from the bis(phenolate) ligand, and two nitrogen atoms from one guanidinato group. The coordination geometry around ytterbium can be described as a distorted octahedron. It was found that these ytterbium guanidinato complexes are highly efficient catalysts for the hydrophosphonylation reaction of various aldehydes under mild conditions.

Published
2015

3. Asymmetric Epoxidation of Unsaturated Ketones Catalyzed by Heterobimetallic Rare Earth–Lithium Complexes Bearing Phenoxy-Functionalized Chiral Diphenylprolinolate Ligand

Author

Yufang Tan, Bei Zhao, Tao Feng, Qinqin Qian, Qi Shen, and Yingming Yao

Subjects
Chalcone, Ionic radius, Molecular Structure, Proline, Chemistry, Stereochemistry, Ligand, Organic Chemistry, Rare earth, chemistry.chemical_element, Ketones, Lithium, Ligands, Biochemistry, Medicinal chemistry, Catalysis, chemistry.chemical_compound, Coordination Complexes, Epoxy Compounds, Phenol, Metals, Rare Earth, Ytterbium, Physical and Theoretical Chemistry
Abstract

Four novel heterobimetallic complexes [REL2]{[(THF)3Li]2(μ-Cl)} stabilized by chiral phenoxy-functionalized prolinolate (RE = Yb (1), Y (2), Sm (3), Nd (4), H2L = (S)-2,4-di-tert-butyl-6-[[2-(hydroxydiphenylmethyl)pyrrolidin-1-yl]methyl]phenol have been synthesized and characterized. These readily available complexes are highly active in catalyzing the epoxidation of α,β-unsaturated ketones, while the enantioselectivity varies according to the ionic radii of the rare earth center. A series of chalcone derivatives were converted to chiral epoxides in 80 → 99% ee at 0 °C using TBHP as the oxidant in the presence of 10 mol % of 1.

Published
2014

4. ChemInform Abstract: Synthesis and Characterization of Ytterbium Guanidinates Stabilized by Bridged Bis(phenolate) Ligand and Their Application for the Hydrophosphonylation Reaction of Aldehydes

Author

Yaorong Wang, Qinqin Qian, Tinghua Zeng, Qi Shen, and Yingming Yao

Subjects
Ytterbium, Chemistry, Ligand, Polymer chemistry, Organic chemistry, chemistry.chemical_element, General Medicine, Catalysis, Characterization (materials science)
Abstract

Ytterbium guanidinates are shown to be highly efficient catalysts for the hydrophosphonylation of various aldehydes (16 examples) under mild conditions.

Published
2015

6. Lanthanide anilido complexes: synthesis, characterization, and use as highly efficient catalysts for hydrophosphonylation of aldehydes and unactivated ketones.

Author

Chengwei Liu, Qinqin Qian, Kun Nie, Yaorong Wang, Qi Shen, Dan Yuan, and Yingming Yao

Subjects
*RARE earth metal compound synthesis, *ALDEHYDES, *KETONES, *CATALYTIC activity, *ANILIDES, *PHOSPHONATES, *NUCLEAR magnetic resonance
Abstract

Lanthanide anilido complexes stabilized by the 2,6-diisopropylanilido ligand have been synthesized and characterized, and their catalytic activity for hydrophosphonylation reaction was explored. A reaction of anhydrous LnCl3 with 5 equivalents of LiNHPh-iPr2-2,6 in THF generated the heterobimetallic lanthanide-lithium anilido complexes (2,6-iPr2PhNH)5LnLi2(THF)2 [Ln = Sm(1), Nd(2), Y(3)] in good isolated yields. These complexes are well characterized by elemental analysis, IR, NMR (for complex 3) and singlecrystal structure determination. Complexes 1-3 are isostructural. In these complexes, the lanthanide metal ion is five-coordinated by five nitrogen atoms from five 2,6-diisopropylanilido ligands to form a distorted trigonal bipyramidal geometry. The lithium ion is coordinated by two nitrogen atoms from two 2,6-diisopropylanilido ligands, and one oxygen atom from a THF molecule. It was found that these simple lanthanide anilido complexes are highly efficient for catalyzing hydrophosphonylation reactions of various aldehydes and unactivated ketones to generate α-hydroxyphosphonates in good to excellent yields (up to 99%) within a short time (5 min for aldehydes, 20 min for ketones). Furthermore, the mechanism of hydrophosphonylation reactions has also been elucidated via 1H NMR monitoring of reaction. [ABSTRACT FROM AUTHOR]

Published
2014
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