Cooperative Stereocontrol by Proximal and Distal Chlorine Substituents in the Chiral Lewis Base‐catalyzed Kinetic Resolution of cis ‐Vinyl Epoxide

2019 ◽  
Vol 40 (8) ◽  
pp. 835-838
Author(s):  
Jungi Jung ◽  
Jae Hee Kim ◽  
Hanna Kim ◽  
Seungyeop Lee ◽  
Jun‐Ho Choi ◽  
...  
Keyword(s):  
Kinetic Resolution ◽  
Lewis Base ◽  
Vinyl Epoxide

scholarly journals Metal-free oxidative cross-coupling enabled practical synthesis of atropisomeric QUINOL and its derivatives

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Peng-Ying Jiang ◽  
Kai-Fang Fan ◽  
Shaoyu Li ◽  
Shao-Hua Xiang ◽  
Bin Tan
Keyword(s):  
Asymmetric Catalysis ◽  
Kinetic Resolution ◽  
Academic Research ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Industrial Applications ◽  
Lewis Base ◽  
Production Costs ◽  
Metal Free ◽  
Base Catalysts

AbstractAs an important platform molecule, atropisomeric QUINOL plays a crucial role in the development of chiral ligands and catalysts in asymmetric catalysis. However, efficient approaches towards QUINOL remain scarce, and the resulting high production costs greatly impede the related academic research as well as downstream industrial applications. Here we report a direct oxidative cross-coupling reaction between isoquinolines and 2-naphthols, providing a straightforward and scalable route to acquire the privileged QUINOL scaffolds in a metal-free manner. Moreover, a NHC-catalyzed kinetic resolution of QUINOL N-oxides with high selectivity factor is established to access two types of promising axially chiral Lewis base catalysts in optically pure forms. The utility of this methodology is further illustrated by facile transformations of the products into QUINAP, an iconic ligand in asymmetric catalysis.

scholarly journals Developing a Methodology for Catalytic Asymmetric Crotylation of Aldehydes

Synlett ◽  
2021 ◽  
Author(s):  
Andrei V. Malkov ◽  
Aleksandr E. Rubtsov
Keyword(s):  
Kinetic Resolution ◽  
Lewis Base ◽  
Chiral Auxiliaries ◽  
Organometallic Reagents ◽  
Total Syntheses ◽  
Base Catalysts ◽  
Homoallylic Alcohols ◽  
Stereogenic Centers ◽  
Long Time ◽  
Lewis Base Catalysts

AbstractAsymmetric crotylation has firmly earned a place among the set of valuable synthetic tools for stereoselective construction of carbon skeletons. For a long time the field was heavily dominated by reagents bearing stoichiometric chiral auxiliaries, but now catalytic methods are gradually taking center stage, and the area continues to develop rapidly. This account focuses primarily on preformed organometallic reagents based on silicon and, to some extent, boron. It narrates our endeavors to design new and efficient chiral Lewis base catalysts for the asymmetric addition of crotyl(trichloro)silanes to aldehydes. It also covers the development of a novel protocol for kinetic resolution of racemic secondary allylboronates to give enantio- and diastereomerically enriched linear homoallylic alcohols. As a separate topic, cross-crotylation of aldehydes by using enantiopure branched homoallylic alcohols as a source of crotyl groups is discussed. Finally, the synthetic credentials of the developed methodology are illustrated by total syntheses of marine natural products, in which crotylation plays a key role in setting up stereogenic centers.1 Introduction2 Pyridine N-Oxides as Lewis Base Catalysts3 Bipyridine N,N′-Dioxides as Lewis Base Catalysts4 Chiral Allylating Reagents5 Synthetic Applications6 Concluding Remarks

scholarly journals Biocatalytic Dynamic Kinetic Resolution for the Synthesis of Atropisomeric Biaryl N-Oxide Lewis Base Catalysts

2016 ◽  
Vol 128 (36) ◽  
pp. 10913-10917 ◽  
Author(s):  
Samantha Staniland ◽  
Ralph W. Adams ◽  
Joseph J. W. McDouall ◽  
Irene Maffucci ◽  
Alessandro Contini ◽  
...  
Keyword(s):  
Kinetic Resolution ◽  
Lewis Base ◽  
Dynamic Kinetic Resolution ◽  
Base Catalysts ◽  
Lewis Base Catalysts

C–O Ring Formation

2015 ◽  
Author(s):  
Tristan H. Lambert
Keyword(s):  
Kinetic Resolution ◽  
Lewis Base ◽  
State University ◽  
Wayne State University ◽  
Northwestern University ◽  
Iminium Ion ◽  
Peking University ◽  
Complete Reversal ◽  
Dyotropic Rearrangement ◽  
The University

A reductive radical cyclization of tetrahydropyran 1 to form bicycle 2 using iron(II) chloride in the presence of NaBH4 was reported (Angew. Chem. Int. Ed. 2012, 51, 6942) by Louis Fensterbank and Cyril Ollivier at the University of Paris and Anny Jutand at the Ecole Normale Supérieure. The enantioselective conversion of tetrahydrofuran 3 to spirocycle 5 via iminium ion-catalyzed hydride transfer/cyclization was developed (Angew. Chem. Int. Ed. 2012, 51, 8811) by Yong-Qiang Tu at Lanzhou University. Daniel Romo at Texas A&M University showed (J. Am. Chem. Soc. 2012, 134, 13348) that enantioenriched tricyclic β-lactone 8 could be readily prepared via dyotropic rearrangement of the diketoacid 6 under catalysis by chiral Lewis base 7. A dyotropic rearrangement was also utilized (Angew. Chem. Int. Ed. 2012, 51, 6984) by Zhen Yang at Peking University, Tuoping Luo at H3 Biomedicine in Cambridge, MA, and Yefeng Tang at Tsinghua University for the conversion of 9 to the bicyclic lactone 10. In terms of the enantioselective synthesis of β-lactones, Karl Scheidt at Northwestern University found that NHC catalyst 12 effects (Angew. Chem. Int. Ed. 2012, 51, 7309) the dynamic kinetic resolution of aldehyde 11 to furnish the lactone 13 with very high ee. Meanwhile, Xiaomeng Feng at Sichuan University has developed (J. Am Chem. Soc. 2012, 134, 17023) a rare example of an enantioselective Baeyer-Villiger oxidation of 4-alkyl cyclohexanones such as 14. The diastereoselective preparation of tetrahydropyran 18 by Lewis acid-promoted cyclization of cyclopropane 17 was accomplished (Org. Lett. 2012, 14, 6258) by Jin Kun Cha at Wayne State University. Stephen J. Connon at the University of Dublin reported (Chem. Commun. 2012, 48, 6502) the formal cycloaddition of aryl succinic anhydrides such as 18 with aldehydes to produce γ-butyrolactones, including 20, in high ee. The stereodivergent cyclization of 21 via desilylation-induced heteroconjugate addition to produce the complex tetrahydropyran 22 was discovered (Org. Lett. 2012, 14, 5550) by Paul A. Clarke at the University of York. Remarkably, while TFA produced a 13:1 diastereomeric ratio in favor of the cis diastereomer 22, the use of TBAF resulted in complete reversal of diastereoselectivity.

scholarly journals Biocatalytic Dynamic Kinetic Resolution for the Synthesis of Atropisomeric Biaryl N-Oxide Lewis Base Catalysts

2016 ◽  
Vol 55 (36) ◽  
pp. 10755-10759 ◽  
Author(s):  
Samantha Staniland ◽  
Ralph W. Adams ◽  
Joseph J. W. McDouall ◽  
Irene Maffucci ◽  
Alessandro Contini ◽  
...  
Keyword(s):  
Kinetic Resolution ◽  
Lewis Base ◽  
Dynamic Kinetic Resolution ◽  
Base Catalysts ◽  
Lewis Base Catalysts

ChemInform Abstract: Regio- and Enantioselective Synthesis of Azole Hemiaminal Esters by Lewis Base Catalyzed Dynamic Kinetic Resolution.

ChemInform ◽  
2016 ◽  
Vol 47 (38) ◽  
Author(s):  
David W. Piotrowski ◽  
Adam S. Kamlet ◽  
Anne-Marie R. Dechert-Schmitt ◽  
Jiangli Yan ◽  
Thomas A. Brandt ◽  
...  
Keyword(s):  
Kinetic Resolution ◽  
Enantioselective Synthesis ◽  
Lewis Base ◽  
Dynamic Kinetic Resolution

Dynamic Kinetic Resolution in Enantioselective Reductive Amination ofα-Branched Aldehydes by Lewis Base Organocatalyzed Hydrosilylation

2017 ◽  
Vol 2 (14) ◽  
pp. 4076-4078 ◽  
Author(s):  
Fang-Zhi Hu ◽  
Hui Chen ◽  
Xiao-Ying Xu ◽  
Wei-Cheng Yuan ◽  
Xiao-Mei Zhang
Keyword(s):  
Reductive Amination ◽  
Kinetic Resolution ◽  
Lewis Base ◽  
Dynamic Kinetic Resolution

scholarly journals Enantioselective Lewis Base Catalyzed Phosphonyldifluoromethylation of Allylic Fluorides Using C-Silyl Latent Pronucleophile

2020 ◽  
Author(s):  
You Zi ◽  
Markus Lange ◽  
Ivan Vilotijevic
Keyword(s):  
Kinetic Resolution ◽  
Lewis Base ◽  
Facile Synthesis ◽  
High Stereoselectivity

The first enantioselective phosphonyldifluoromethylation is enabled by the use of diethyl (difluoro(trimethylsilyl)methyl)pho-sphonate reagent as a latent pronuclephile in Lewis base catalyzed substitution of allylic fluorides. The reactions proceed as kinetic resolution to produce both the difluoromethylphosphonate products and the remaining fluorides in good yields and with high stereoselectivity. The use of cinchona based alkaloid catalysts enables the facile synthesis of both enantiomers of the difluoromethylphosphonate products.

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