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Kuiling Ding

Publications and source records attributed to Kuiling Ding.

27 records · Page 2Linked to original sources
PubMed2003

A new type of C2-symmetric bisphospine ligands with a cyclobutane backbone: practical synthesis and application.

[reaction: see text] A highly efficient and practical optical resolution of anti-head-to-head racemic coumarin dimer, (+/-)-5, by molecular complexation with TADDOL (6) through hydrogen bonding and a convenient transformation of enantiopure 5 to a new type of C(2)-symmetric bisphosphine ligand (3) have been achieved. The asymmetric induction efficiency of these chiral bisphosphine ligands was evaluated in Pd-catalyzed asymmetric allylic substitution, affording the allylic substitution products in excellent yield (up to 99%) and enantioselectivity (up to 98.9% ee).

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PubMed2003

Enantioselective catalysis of hetero Diels-Alder reaction and diethylzinc addition using a single catalyst.

[reaction: see text] Integration of two asymmetric reactions in one pot with the promotion of a single catalyst has been achieved in high efficiency and excellent stereoselectivity for hetero Diels-Alder reaction of Danishefsky's diene and diethylzinc addition to aldehydes. The strategy described in the present work demonstrated the ability of a single catalyst to promote two distinct enantioselective reactions in one pot.

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PubMed2002

To probe the origin of activation effect of carboxylic acid and (+)-NLE in tridentated titanium catalyst systems.

The activation effect of carboxylic acid and positive nonlinear effect ((+)-NLE) in tridentated titanium catalyst systems for hetero Diels-Alder reaction and aldol-type reactions has been first elucidated on the basis of X-ray crystal structural analysis of homochiral (pseudo-octahedral coordination geometry with C2 symmetry) and heterochiral (pseudo-octahedral coordination geometry with C1 symmetry) titanium complexes and the observation of their different reactivities with carboxylic acid additive.

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PubMed2002

Dramatically synergetic effect of carboxylic acid additive on tridentate titanium catalyzed enantioselective hetero-diels-alder reaction: additive acceleration and nonlinear effect.

This paper describes the successful development of a group of highly efficient chiral tridentate titanium catalysts for hetero-Diels-Alder reaction of Danishefsky's diene and a variety of aldehydes through ligand and additive diversity. Dramatically synergetic effect of carboxylic acid additives and influence of substituent in chiral Schiff base ligands on the enantioselectivities of the reaction are reported. It was found that a chiral drug Naproxen (A21) was a highly efficient additive for Ti-catalyzed HDA reaction, affording 2-substituted 2,3-dihydro-4H-pyran-4-one in up to 97 % ee and >99 % yields. Quantitative study of the effect of chiral carboxylic acid A21 revealed that the reaction could be accelerated by one order of magnitude. Another interesting feature of present catalytic system is the existence of significant positive nonlinear effect, which indicates that the heterochiral Schiff base-titanium complexes may have higher stability than their homochiral counterparts. As a result, the homochiral Schiff base-titanium complexes with higher ee than that of starting ligand will react with carboxylic acid additive to form the more active species and predominate the catalytic process. The isolation and characterization of stable heterochiral ((+/-)-L1)2Ti complex has also been successful, which strongly supported the explanation for positive nonlinear effect observed in the catalytic system.

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PubMed2002

Acid-free aza Diels-Alder reaction of Danishefsky's diene with imines.

[reaction: see text] A highly efficient aza Diels-Alder reaction of Danishefsky's diene with imines was found to occur in methanol in the absence of any acids at room temperature to give corresponding 2-substituted dihydro-4-pyridone derivatives in high yields. This reaction can be also carried out in a three-component one-pot reaction manner. The reaction was found to proceed through a Mannich-type condensation mechanism.

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PubMed2002

Discovery of exceptionally efficient catalysts for solvent-free enantioselective hetero-Diels-Alder reaction.

Combinatorial coordination chemistry strategy combined with high-throughput screening techniques has been successfully applied to engineering practical enantioselective catalysts for asymmetric hetero-Diels-Alder reaction. The reaction of Danishefsky's diene with a variety of aldehydes can be carried out with 0.1-0.005 mol % of H4-BINOL/Ti/H4-BINOL or H4-BINOL/Ti/H8-BINOL catalysts at room temperature under solvent- and MS-free conditions to afford dihydropyrone derivatives with up to quantitative yield and 99.8% ee.

Aldehydes↗
PubMed2001

Engineering Catalysts for Enantioselective Addition of Diethylzinc to Aldehydes with Racemic Amino Alcohols: Nonlinear Effects in Asymmetric Deactivation of Racemic Catalysts Financial support from the National Natural Science Foundation of China, the Chinese Academy of Sciences, the Major Basic Research Development Program of China (Grant no. G2000077506), and the Science and Technology Commission of Shanghai Municipality is gratefully acknowledged.

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