Stereodivergent Pd/Cu catalysis: asymmetric alkylation of racemic symmetrical 1,3-diphenyl allyl acetates

2021 ◽  
Vol 19 (9) ◽  
pp. 1955-1959 ◽  
Author(s):  
Ling Zhao ◽  
Guanlin Li ◽  
Rui He ◽  
Penglin Liu ◽  
Feijun Wang ◽  
...  
Keyword(s):  
Catalyst System ◽  
Allylic Alkylation ◽  
Asymmetric Allylic Alkylation ◽  
Asymmetric Alkylation ◽  
Cu Catalyst ◽  
Imino Esters

A stereodivergent Pd/Cu catalyst system was developed, which was successfully applied to the asymmetric allylic alkylation of symmetrical 1,3-disubstituted allyl acetates with prochiral imino esters in a fully stereodivergent manner.

Coordination of the Trost modular ligand to palladium allyl fragments: Oligomers, monomers and memory effects in catalysis

2004 ◽  
Vol 76 (3) ◽  
pp. 589-601 ◽  
Author(s):  
G. C. Lloyd-Jones ◽  
S. C. Stephen ◽  
I. J. S. Fairlamb ◽  
Aina Martorell ◽  
Beatriz Dominguez ◽  
...  
Keyword(s):  
Crucial Role ◽  
Dynamic Equilibrium ◽  
Catalyst System ◽  
Alkylation Reaction ◽  
Allylic Alkylation ◽  
Monomeric Form ◽  
X Ray Diffraction ◽  
Asymmetric Allylic Alkylation ◽  
X Ray ◽  
Oligomeric Form

Reaction of the C2-symmetric "Trost modular ligand" with cationic Pd(II) allyl fragments allows isolation of air- and bench-stable pro-catalysts for the asymmetric allylic alkylation of racemic cycloalkenyl esters. In solution, three distinct complexation modes are observed. When mixed in a ligand/Pd ratio of 1/2, a binuclear bis-P,O-chelate complex is generated. This species does not induce enantioselectivity in the reaction. In contrast, with a ligand/Pd ratio of 1/1, a highly enantioselective, P,P-coordinated pro-catalyst system is generated in which there are two basic coordination modes: monomeric and oligomeric. The monomeric form is mononuclear and exists as two 13-membered chelates, isomeric through loss of C2-symmetry in the ligand. The oligomeric form is polynuclear and forms chains and rings of alternating ligand and cationic Pd(allyl) units, one of which was identified by single-crystal X-ray diffraction. In solution, the monomeric and oligomeric species are in dynamic equilibrium with populations and interconversion rates controlled by concentration, temperature, and counterion. Isotopic desymmetrization analysis suggests that the monomer-oligomer equilibrium plays a crucial role in both the selectivity and efficiency of the asymmetric allylic alkylation reaction.

scholarly journals Copper-catalysed asymmetric allylic alkylation of alkylzirconocenes to racemic 3,6-dihydro-2H-pyrans

2015 ◽  
Vol 11 ◽  
pp. 2435-2443 ◽  
Author(s):  
Emeline Rideau ◽  
Stephen P Fletcher
Keyword(s):  
Nmr Spectroscopy ◽  
Reaction Mechanisms ◽  
Statistical Approach ◽  
Linear Optimization ◽  
Allylic Alkylation ◽  
Asymmetric Allylic Alkylation ◽  
Asymmetric Alkylation ◽  
H Nmr ◽  
Diethyl Phosphate ◽  
Insight Into

Asymmetric allylic alkylation is a powerful reaction that allows the enantioselective formation of C–C bonds. Here we describe the asymmetric alkylation of alkylzirconium species to racemic 3,6-dihydro-2H-pyrans. Two systems were examined: 3-chloro-3,6-dihydro-2H-pyran using linear optimization (45–93% ee, up to 33% yield, 5 examples) and 3,6-dihydro-2H-pyran-3-yl diethyl phosphate with the assistance of a design of experiments statistical approach (83% ee, 12% yield). 1H NMR spectroscopy was used to gain insight into the reaction mechanisms.

Novel Chiral Ligands for Palladium-catalyzed Asymmetric Allylic Alkylation/ Asymmetric Tsuji-Trost Reaction: A Review

2019 ◽  
Vol 23 (11) ◽  
pp. 1168-1213 ◽  
Author(s):  
Samar Noreen ◽  
Ameer Fawad Zahoor ◽  
Sajjad Ahmad ◽  
Irum Shahzadi ◽  
Ali Irfan ◽  
...  
Keyword(s):  
Asymmetric Catalysis ◽  
Enantioselective Synthesis ◽  
Chiral Ligands ◽  
Allylic Alkylation ◽  
Research Groups ◽  
Asymmetric Allylic Alkylation ◽  
Catalytic Potential ◽  
Long Time ◽  
Palladium Catalyzed ◽  
Alkylation Reactions

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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