Palladium‐Catalyzed Asymmetric Quaternary Stereocenter Formation

Gottumukkala, Aditya L.; Matcha, Kiran; Lutz, Martin; Vries, Johannes G. de; Minnaard, Adriaan J.

doi:10.1002/chem.201200694

Cited by 94 publications

(34 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…18 However, we found that highly polar solvents failed to produce product (Table 4, entries 2 and 3). Switching to dicationic palladium by employing tetrakis acetonitrile palladium(II) tetrafluoroborate facilitated no conversion in methanol at a variety of temperatures (entries 4–6), or as a mixture with dichloroethane as cosolvent (entry 6).…”

Section: Development and Optimization Of Reaction Conditionsmentioning

confidence: 91%

Synthesis of diverse β-quaternary ketones via palladium-catalyzed asymmetric conjugate addition of arylboronic acids to cyclic enones

et al. 2015

View full text Add to dashboard Cite

The development and optimization of a palladium-catalyzed asymmetric conjugate addition of arylboronic acids to cyclic enone conjugate acceptors is described. These reactions employ air-stable and readily-available reagents in an operationally simple and robust transformation that yields β-quaternary ketones in high yields and enantioselectivities. Notably, the reaction itself is highly tolerant of atmospheric oxygen and moisture and therefore does not require the use of dry or deoxygenated solvents, specially purified reagents, or an inert atmosphere. The ring size and β-substituent of the enone are highly variable, and a wide variety of β-quaternary ketones can be synthesized. More recently, the use of NH4PF6 has further expanded the substrate scope to include heteroatom-containing arylboronic acids and β-acyl enone substrates.

show abstract

Section: Development and Optimization Of Reaction Conditionsmentioning

confidence: 91%

Synthesis of diverse β-quaternary ketones via palladium-catalyzed asymmetric conjugate addition of arylboronic acids to cyclic enones

et al. 2015

View full text Add to dashboard Cite

show abstract

“…77 A related palladium catalyzed conjugate addition of arylboronic acids to acyclic enones was reported but enantioselectivities were quite low (not shown). 78 …”

Section: Acyclic Quaternary Carbon Stereocentersmentioning

confidence: 99%

Acyclic Quaternary Carbon Stereocenters via Enantioselective Transition Metal Catalysis

2017

View full text Add to dashboard Cite

Whereas numerous asymmetric methods for formation of quaternary carbon stereocenters in cyclic systems have been documented, the construction of acyclic quaternary carbon stereocenters with control of absolute stereochemistry remains a formidable challenge. This review summarizes enantioselective methods for the construction of acyclic quaternary carbon stereocenters from achiral or chiral racemic reactants via transition metal catalysis.

show abstract

“…Indeed, recent publications prove palladium-catalyzed conjugate addition to be a burgeoning field of research. 16 After the initial disclosure, we observed that in addition to catalyzing conjugate additions to 5-, 6-, and 7-membered enones, the Pd/PyOx catalyst successfully reacted with chromones and 4-quinolones. 17 Intrigued by the broad substrate scope and operational simplicity of this highly asymmetric process, we conducted a thorough study to optimize the reaction conditions, including measures to reduce the catalyst loading, lower the reaction temperature, and further generalize the substrate scope.…”

Section: Introductionmentioning

confidence: 98%

Mechanism and Enantioselectivity in Palladium-Catalyzed Conjugate Addition of Arylboronic Acids to β-Substituted Cyclic Enones: Insights from Computation and Experiment

et al. 2013

View full text Add to dashboard Cite

Enantioselective conjugate additions of arylboronic acids to β-substituted cyclic enones have been reported previously from our laboratories. Air and moisture tolerant conditions were achieved with a catalyst derived in situ from palladium(II) trifluoroacetate and the chiral ligand (S)-t-BuPyOx. We now report a combined experimental and computational investigation on the mechanism, the nature of the active catalyst, the origins of the enantioselectivity, and the stereoelectronic effects of the ligand and the substrates of this transformation. Enantioselectivity is controlled primarily by steric repulsions between the t-Bu group of the chiral ligand and the α-methylene hydrogens of the enone substrate in the enantiodetermining carbopalladation step. Computations indicate that the reaction occurs via formation of a cationic arylpalladium(II) species, and subsequent carbopalladation of the enone olefin forms the key carbon-carbon bond. Studies of non-linear effects and stoichiometric and catalytic reactions of isolated (PyOx)Pd(Ph)I complexes show that a monomeric arylpalladium-ligand complex is the active species in the selectivity-determining step. The addition of water and ammonium hexafluorophosphate synergistically increases the rate of the reaction, corroborating the hypothesis that a cationic palladium species is involved in the reaction pathway. These additives also allow the reaction to be performed at 40 °C and facilitate an expanded substrate scope.

show abstract

Palladium‐Catalyzed Asymmetric Quaternary Stereocenter Formation

Cited by 94 publications

References 55 publications

Synthesis of diverse β-quaternary ketones via palladium-catalyzed asymmetric conjugate addition of arylboronic acids to cyclic enones

Synthesis of diverse β-quaternary ketones via palladium-catalyzed asymmetric conjugate addition of arylboronic acids to cyclic enones

Acyclic Quaternary Carbon Stereocenters via Enantioselective Transition Metal Catalysis

Mechanism and Enantioselectivity in Palladium-Catalyzed Conjugate Addition of Arylboronic Acids to β-Substituted Cyclic Enones: Insights from Computation and Experiment

Contact Info

Product

Resources

About