Zn-Catalyzed Enantioselective Allylation and Allenylation of Isatins by virtue of Proline-derived Chiral Ligand

2022 ◽  
Author(s):  
Kuiliang Li ◽  
Xiang Sun ◽  
Shuangshuang Zhao ◽  
Tong Li ◽  
Zhenggen Zha ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Chiral Ligand ◽  
Asymmetric Allylation ◽  
Optically Pure

An asymmetric allylation and allenylation of isatins with facile organoboron reagents was developed under the catalysis of Lewis acid. A series of optically pure 3-allyl-3-hydroxyoxindoles and 3-allenyl-3-hydroxyoxindoles can be obtained...

Enantioselective Syntheses of Flavonoid Diels-Alder Natural Products: A Review

2018 ◽  
Vol 15 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Shah Bakhtiar Nasir ◽  
Noorsaadah Abd Rahman ◽  
Chin Fei Chee
Keyword(s):  
Natural Products ◽  
Organic Synthesis ◽  
Lewis Acid ◽  
Alder Reaction ◽  
Diels Alder ◽  
Enantioselective Synthesis ◽  
Chiral Ligand ◽  
Asymmetric Syntheses ◽  
Diels Alder Reaction ◽  
Enantioselective Syntheses

Background: The Diels-Alder reaction has been widely utilised in the syntheses of biologically important natural products over the years and continues to greatly impact modern synthetic methodology. Recent discovery of chiral organocatalysts, auxiliaries and ligands in organic synthesis has paved the way for their application in Diels-Alder chemistry with the goal to improve efficiency as well as stereochemistry. Objective: The review focuses on asymmetric syntheses of flavonoid Diels-Alder natural products that utilize chiral ligand-Lewis acid complexes through various illustrative examples. Conclusion: It is clear from the review that a significant amount of research has been done investigating various types of catalysts and chiral ligand-Lewis acid complexes for the enantioselective synthesis of flavonoid Diels-Alder natural products. The results have demonstrated improved yield and enantioselectivity. Much emphasis has been placed on the synthesis but important mechanistic work aimed at understanding the enantioselectivity has also been discussed.

An enantioselective strategy for the total synthesis of (S)-tylophorine via catalytic asymmetric allylation and a one-pot DMAP-promoted isocyanate formation/Lewis acid catalyzed cyclization sequence

2014 ◽  
Vol 12 (22) ◽  
pp. 3616-3621 ◽  
Author(s):  
Bo Su ◽  
Hui Zhang ◽  
Meng Deng ◽  
Qingmin Wang
Keyword(s):  
Total Synthesis ◽  
Lewis Acid ◽  
Asymmetric Allylation ◽  
One Pot ◽  
Acid Catalyzed ◽  
Catalytic Asymmetric

A novel total synthesis of (S)-tylophorine is reported, featuring asymmetric allylation and cascade isocyanate formation and cyclization.

scholarly journals Origin of Enantioselectivity Reversal in Lewis Acid-Catalyzed Michael Additions Relying on the Same Chiral Source

2020 ◽  
Author(s):  
Paul S. Riehl ◽  
Alistair D. Richardson ◽  
Tatsuhiro Sakamoto ◽  
Jolene P. Reid ◽  
Corinna Schindler
Keyword(s):  
Asymmetric Catalysis ◽  
Lewis Acid ◽  
Chiral Ligand ◽  
Potential Significance ◽  
Kinetics And Thermodynamics ◽  
Important Concept ◽  
Michael Additions ◽  
Acid Catalyzed ◽  
Mechanistic Understanding

Enantiodivergence is an important concept in asymmetric catalysis that enables access to both enantiomers of a product relying on the same chiral source. This strategy is particularly appealing as an alternate approach when only one enantiomer of the required chiral ligand is readily accessible but both enantiomers of the product are desired. Despite their potential significance, general catalytic methods to induce reversal in enantioselectivity remain underdeveloped. Herein we report our studies focused on elucidating the origin of enantioselectivity reversal in Lewis acid-catalyzed Michael additions relying on the same enantiomer of ligand as the chiral source. Our results provide a detailed mechanistic understanding of this transformation based on experimental and computational investigations which reveal the important interplay between kinetics and thermodynamics responsible for the observed enantiodivergence.

scholarly journals (±)-trans-1,2-Cyclohexanediamine-Based Bis(NHC) Ligand for Cu-Catalyzed Asymmetric Conjugate Addition Reaction

Catalysts ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 780 ◽  
Author(s):  
Azusa Ishibashi ◽  
Shun Kamihigashi ◽  
Yuuki Iwai ◽  
Satoshi Sakaguchi
Keyword(s):  
Catalytic System ◽  
Amino Alcohol ◽  
Addition Reaction ◽  
Conjugate Addition ◽  
Addition Reactions ◽  
Chiral Ligand ◽  
Facial Selectivity ◽  
Ligand Precursors ◽  
Optically Pure

Bis(NHC) ligand precursors, L1, based on trans-1,2-diaminocyclohexane were designed and synthesized. To introduce chirality at the hydroxyamide side arm on the NHC of L1, a chiral β-amino alcohol, such as enantiopure leucinol, was used. Cu-catalyzed asymmetric conjugate addition reactions of cyclic and acyclic enones with Et2Zn were selected to evaluate the performance of L1 as a chiral ligand. For the reaction of cyclic enone, a combination of [bis(trimethylsilyl)acetylene]-(hexafluoroacetylacetonato)copper(I) (Cu(hfacac)(btmsa)) with a (±)-trans-1,2-cyclohexanediamine-based bis(NHC) ligand precursor, (rac; S,S)-L1, which was prepared from (S)-leucinol, was the most effective. Thus, treating 2-cyclohexen-1-one (3) with Et2Zn in the presence of catalytic amounts of Cu(hfacac)(btmsa) and (rac; S,S)-L1 afforded (R)-3-ethylcyclohexanone ((R)-4) with 97% ee. Similarly, use of (rac; R,R)-L1, which was prepared from (R)-leucinol, produced (S)-4 with 97% ee. Conversely, for the asymmetric 1,4-addition reaction of the acyclic enone, optically pure (−)-trans-1,2-cyclohexanediamine-based bis(NHC) ligand precursor, (R,R; S,S)-L1, worked efficiently. For example, 3-nonen-2-one (5) was reacted with Et2Zn using the CuOAc/(R,R; S,S)-L1 catalytic system to afford (R)-4-ethylnonan-2-one ((R)-6) with 90% ee. Furthermore, initially changing the counterion of the Cu precatalyst between an OAc and a ClO4 ligand on the metal reversed the facial selectivity of the approach of the substrates. Thus, the conjugate addition reaction of 5 with Et2Zn using the Cu(ClO4)2/(R,R; S,S)-L1 catalytic system, afforded (S)-6 with 75% ee.

ChemInform Abstract: Asymmetric Allylation of Aldehydes and Glyoxylates Through ′C-Centered′ Chiral Pentacoordinate Allylsilicates or Promoted by Lewis Acid.

ChemInform ◽  
2010 ◽  
Vol 30 (28) ◽  
pp. no-no
Author(s):  
Dong Wang ◽  
Zhi Gang Wang ◽  
Ming Wen Wang ◽  
Yong Jun Chen ◽  
Li Liu ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Asymmetric Allylation

Catalytic asymmetric allylation using a chiral (acyloxy)borane complex as a versatile Lewis acid catalyst

1993 ◽  
Vol 115 (24) ◽  
pp. 11490-11495 ◽  
Author(s):  
Kazuaki Ishihara ◽  
Makoto Mouri ◽  
Qingzhi Gao ◽  
Tohru Maruyama ◽  
Kyoji Furuta ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Acid Catalyst ◽  
Asymmetric Allylation ◽  
Lewis Acid Catalyst ◽  
Catalytic Asymmetric
Sign in / Sign up

Export Citation Format

Share Document