Kinetic resolution of β-ketoesters with quaternary stereocenters via a carbene-catalyzed benzoin reaction

2019 ◽  
Vol 17 (8) ◽  
pp. 2169-2173 ◽  
Author(s):  
Syeda Tazeen Zehra ◽  
Guoxiang Zhang ◽  
Shuang Yang ◽  
Xinqiang Fang
Keyword(s):  
Kinetic Resolution ◽  
Quaternary Stereocenters

N-Heterocyclic carbene-catalyzed kinetic resolution is used to produce enantioenriched β-ketoesters with quaternary stereocenters. Sterically bulky substituents such as benzyl, allyl, phenyl and cyclopropyl groups are all tolerated in this method.

Kinetic resolution of 2,2-disubstituted-1,3-diketones via carbene catalysis

2019 ◽  
Vol 6 (3) ◽  
pp. 290-298 ◽  
Author(s):  
Weici Xu ◽  
Yuanzhen Li ◽  
Rui Liu ◽  
Shuang Yang ◽  
Jian Liu ◽  
...  
Keyword(s):  
Kinetic Resolution ◽  
Quaternary Stereocenters ◽  
First Time

Organocatalytic kinetic resolution of 1,3-diketones with central quaternary stereocenters was achieved for the first time. The resolution proceeds via two basic modes, and the inherent principles between the different combinations of ketone groups and the resolution patterns were also disclosed.

ChemInform Abstract: Enantioselective Formation of Cyano-Bearing All-Carbon Quaternary Stereocenters: Copper-Catalyzed N-Arylation via Kinetic Resolution.

ChemInform ◽  
2016 ◽  
Vol 47 (6) ◽  
pp. no-no
Author(s):  
Yan Long ◽  
Jialing Shi ◽  
Haoqiang Liang ◽  
Youlin Zeng ◽  
Qian Cai
Keyword(s):  
Kinetic Resolution ◽  
Quaternary Stereocenters

Construction of Stereochemical Arrays

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Kinetic Resolution ◽  
Alder Reaction ◽  
State University ◽  
Rhodium Catalysis ◽  
Colorado State University ◽  
Allyl Sulfide ◽  
Institute Of Technology ◽  
Quaternary Stereocenters ◽  
The University ◽  
Technological University

The unprecedented enantioselective 1,8-addition of azlactone 1 to acylpyrrole 2 catalyzed by triaminophosphorane 3 was reported (J. Am. Chem. Soc. 2012, 134, 19370) by Takashi Ooi at Nagoya University. Tomislav Rovis at Colorado State University developed (Angew. Chem. Int. Ed. 2012, 51, 12330) the asymmetric oxidative hetero-Diels-Alder reaction of propionaldehyde (5) and ketone 6 to produce lactone 8, catalyzed by NHC catalyst 7 in the presence of phenazine. A related NHC catalyst 11 was utilized (Angew. Chem. Int. Ed. 2012, 51, 8276) by Xue-Wei Liu at Nanyang Technological University for the homoenolate addition of enal 9 to nitrodiene 10 to furnish 12 with high ee. The vinylogous conjugate addition of butenolide 13 to 15 to produce 16 with exquisite stereoselectivity was accomplished (Angew. Chem. Int. Ed. 2012, 51, 10069) by Kuo-Wei Huang at KAUST, Choon-Hong Tan at Henan University and Nanyang Technological University, and Zhiyong Jiang at Henan University. The enantioselective production of lactone 18 was achieved (J. Am. Chem. Soc. 2012, 134, 20197) by Jeffrey S. Johnson at the University of North Carolina at Chapel Hill by dynamic kinetic resolution (DKR) of α-keto ester 17. A related DKR strategy was employed (Org. Lett. 2012, 14, 6334) by Brinton Seashore-Ludlow at the KTH Royal Institute of Technology and Peter Somfai at Lund University in Sweden and the University of Tartu in Estonia for hydrogenation of α-amino-β-ketoester 19 to furnish aminoalcohol 21 with high Shigeki Matsunaga and Motomu Kanai at the University of Tokyo developed (Angew. Chem. Int. Ed. 2012, 51, 10275) a unique strategy for the selective production of the cross-aldol adduct 24 by in situ generation of an aldehyde enolate from allyloxyborane 23 under rhodium catalysis. The highly diastereoselective construction of adduct 26 bearing two adjacent quaternary stereocenters by ketone allylation with allyl sulfide 25 was reported (Angew. Chem. Int. Ed. 2012, 51, 7263) by Takeshi Takeda at the Tokyo University of Agriculture and Technology. Wen-Hao Hu at East China Normal University reported (Nature Chem. 2012, 4, 733) the enantioselective three-component coupling of diazoester 27, N-benzylindole (28), and imine 29 to furnish 31 under the action of Rh2(OAc)4 and phosphoric acid 30.

Synthesis of B-ring-fluorinated (−)-epicatechin gallate derivatives

2020 ◽  
Vol 18 (21) ◽  
pp. 4024-4028
Author(s):  
David D. S. Thieltges ◽  
Kai D. Baumgarten ◽  
Carina S. Michaelis ◽  
Constantin Czekelius
Keyword(s):  
Kinetic Resolution ◽  
Convergent Sequence ◽  
Epicatechin Gallate

Electronically modified, fluorinated catechins and epicatechins are enantioselectively synthesized in a short, convergent sequence via kinetic resolution.

Probing the Parallel Kinetic Resolution of Racemic Oxazolidinones using Quasi-enantiomeric Profens

2006 ◽  
Author(s):  
Jason Eames ◽  
Gregory Coumbarides ◽  
Marco Dingjan ◽  
Tony Flinn ◽  
Northern Northen ◽  
...  
Keyword(s):  
Kinetic Resolution ◽  
Parallel Kinetic Resolution

Catalyst- and Silane- Controlled Enantioselective Hydrofunctionalization of Alkenes by Cobalt-Catalyzed Hydrogen Atom Transfer and Radical-Polar Crossover

2020 ◽  
Author(s):  
Kousuke Ebisawa ◽  
Kana Izumi ◽  
Yuka Ooka ◽  
Hiroaki Kato ◽  
Sayori Kanazawa ◽  
...  
Keyword(s):  
Hydrogen Atom ◽  
Absolute Configuration ◽  
Kinetic Resolution ◽  
Hydrogen Atom Transfer ◽  
Biologically Active ◽  
Atom Transfer ◽  
High Concentration ◽  
Chain Reaction ◽  
Radical Chain ◽  
Radical Chain Reaction

Catalytic enantioselective synthesis of tetrahydrofurans, which are found in the structures of many biologically active natural products, via a transition-metal catalyzed-hydrogen atom transfer (TM-HAT) and radical-polar crossover (RPC) mechanism is described herein. Hydroalkoxylation of non-conjugated alkenes proceeded efficiently with excellent enantioselectivity (up to 94% ee) using a suitable chiral cobalt catalyst, <i>N</i>-fluoro-2,4,6-collidinium tetrafluoroborate, and diethylsilane. Surprisingly, absolute configuration of the product was highly dependent on the steric hindrance of the silane. Slow addition of the silane, the dioxygen effect in the solvent, thermal dependency, and DFT calculation results supported the unprecedented scenario of two competing selective mechanisms. For the less-hindered diethylsilane, a high concentration of diffused carbon-centered radicals invoked diastereoenrichment of an alkylcobalt(III) intermediate by a radical chain reaction, which eventually determined the absolute configuration of the product. On the other hand, a more hindered silane resulted in less opportunity for radical chain reaction, instead facilitating enantioselective kinetic resolution during the late-stage nucleophilic displacement of the alkylcobalt(IV) intermediate.

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