ChemInform Abstract: The Design and Synthesis of Planar Chiral Ligands and Their Application to Asymmetric Catalysis

Background: Asymmetric catalysis holds a prestigious role in organic syntheses since a long time and chiral inductors such as ligands have been used to achieve the utmost desired results at this pitch. The asymmetric version of Tsuji-Trost allylation has played a crucial role in enantioselective synthesis. Various chiral ligands have been known for Pdcatalyzed Asymmetric Allylic Alkylation (AAA) reactions and exhibited excellent catalytic potential. The use of chiral ligands as asymmetric inductors has widened the scope of Tsuji-Trost allylic alkylation reactions. Conclusion: Therefore, in this review article, a variety of chiral inductors or ligands have been focused for palladium catalyzed asymmetric allylic alkylation (Tsuji-Trost allylation) and in this regard, recently reported literature (2013-2017) has been described. The use of ligands causes the induction of enantiodiscrimination to the allylated products, therefore, the syntheses of various kinds of ligands have been targeted by many research groups to employ in Pd-catalyzed AAA reactions.

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Helical Poly(quinoxaline-2,3-diyl)s Bearing Metal-Binding Sites as Polymer-Based Chiral Ligands for Asymmetric Catalysis

Angewandte Chemie International Edition ◽

10.1002/anie.200803719 ◽

2009 ◽

Vol 48 (3) ◽

pp. 539-542 ◽

Cited By ~ 142

Author(s):

Takeshi Yamamoto ◽

Michinori Suginome

Keyword(s):

Asymmetric Catalysis ◽

Metal Binding ◽

Binding Sites ◽

Chiral Ligands ◽

Metal Binding Sites

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Computational Insight into the Rope-Skipping Isomerization of Diarylether Cyclophanes

Symmetry ◽

10.3390/sym13112127 ◽

2021 ◽

Vol 13 (11) ◽

pp. 2127

Author(s):

Thomas J. Summers ◽

Hrishikesh Tupkar ◽

Tyler M. Ozvat ◽

Zoë Tregillus ◽

Kenneth A. Miller ◽

...

Keyword(s):

Asymmetric Catalysis ◽

Room Temperature ◽

Chemical Bonds ◽

Chiral Molecules ◽

Free Energies ◽

Design And Synthesis ◽

The Impact ◽

Rope Skipping ◽

Temperature Factors ◽

Insight Into

The restricted rotation of chemical bonds may lead to the formation of stable, conformationally chiral molecules. While the asymmetry in chiral molecules is generally observed in the presence of one or more stereocenters, asymmetry exhibited by conformational chirality in compounds lacking stereocenters, called atropisomerism, depends on structural and temperature factors that are still not fully understood. This atropisomerism is observed in natural diarylether heptanoids where the length of the intramolecular tether constrains the compounds to isolable enantiomers at room temperature. In this work, we examine the impact tether length has on the activation free energies to isomerization of a diarylether cyclophane substructure with a tether ranging from 6 to 14 carbons. Racemization activation energies are observed to decay from 48 kcal/mol for a 7-carbon tether to 9.2 kcal/mol for a 14-carbon tether. Synthetic efforts to experimentally test these constraints are also presented. This work will likely guide the design and synthesis of novel asymmetric cyclophanes that will be of interest in the catalysis community given the importance of atropisomeric ligands in the field of asymmetric catalysis.

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