A New Class of Non-<i>C</i><sub>2</sub>-Symmetric Ligands for Oxidative and Redox-Neutral Palladium-Catalyzed Asymmetric Allylic Alkylations of 1,3-Diketones

Trost, Barry M.; Donckèle, Etienne J.; Thaisrivongs, David A.; Osipov, Maksim; Masters, James T.

doi:10.1021/jacs.5b00786

Cited by 90 publications

(38 citation statements)

References 81 publications

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“…Our approach herein was to examine non–C 2 -symmetric central chirality, and to investigate topologies not previously explored ( 106 ), with a particular focus on chiral 1,2-diamines and their derivative salens as chiral motifs with wide-ranging potential in asymmetric catalysis. Systems built around amino acid, terpenoid, and carbohydrate scaffolds were initially explored.…”

Section: Introductionmentioning

confidence: 99%

Mini-ISES identifies promising carbafructopyranose-based salens for asymmetric catalysis: Tuning ligand shape via the anomeric effect

et al. 2015

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This study introduces new methods of screening for and tuning chiral space and in so doing identifies a promising set of chiral ligands for asymmetric synthesis. The carbafructopyranosyl-1,2-diamine(s) and salens constructed therefrom are particularly compelling. It is shown that by removing the native anomeric effect in this ligand family, one can tune chiral ligand shape and improve chiral bias. This concept is demonstrated by a combination of (i) x-ray crystallographic structure determination, (ii) assessment of catalytic performance, and (iii) consideration of the anomeric effect and its underlying dipolar basis. The title ligands were identified by a new mini version of the in situ enzymatic screening (ISES) procedure through which catalyst-ligand combinations are screened in parallel, and information on relative rate and enantioselectivity is obtained in real time, without the need to quench reactions or draw aliquots. Mini-ISES brings the technique into the nanomole regime (200 to 350 nmol catalyst/20 μml organic volume) commensurate with emerging trends in reaction development/process chemistry. The best-performing β-d-carbafructopyranosyl-1,2-diamine–derived salen ligand discovered here outperforms the best known organometallic and enzymatic catalysts for the hydrolytic kinetic resolution of 3-phenylpropylene oxide, one of several substrates examined for which the ligand is “matched.” This ligand scaffold defines a new swath of chiral space, and anomeric effect tunability defines a new concept in shaping that chiral space. Both this ligand set and the anomeric shape-tuning concept are expected to find broad application, given the value of chiral 1,2-diamines and salens constructed from these in asymmetric catalysis.

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Section: Introductionmentioning

confidence: 99%

Mini-ISES identifies promising carbafructopyranose-based salens for asymmetric catalysis: Tuning ligand shape via the anomeric effect

et al. 2015

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“…Allylic functionalization provides a direct path to chiral synthons with a newly formed stereocenter from petrochemical feedstocks while preserving the olefin functionality as a handle for further elaboration. Various metal-based catalysts have been discovered for the enantioselective allylic C–H oxidation of simple alkenes with cyclic or terminal double bonds 8–16 . However, a general and selective allylic oxidation remains elusive with the more common internal alkenes.…”

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confidence: 99%

Catalytic allylic oxidation of internal alkenes to a multifunctional chiral building block

Bayeh

Tambar

2017

Nature

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The stereoselective oxidation of hydrocarbons represents one of the most significant advances in synthetic chemistry over the last fifty years1–3. Inspired by nature, chemists have developed enantioselective dihydroxylations, epoxidations, and other oxidations of unsaturated hydrocarbons. More recently, the catalytic enantioselective allylic C–H oxidation of alkenes has emerged as a powerful chemical strategy, streamlining the production of pharmaceuticals, natural products, fine chemicals and other functional materials4–7. Allylic functionalization provides a direct path to chiral synthons with a newly formed stereocenter from petrochemical feedstocks while preserving the olefin functionality as a handle for further elaboration. Various metal-based catalysts have been discovered for the enantioselective allylic C–H oxidation of simple alkenes with cyclic or terminal double bonds8–16. However, a general and selective allylic oxidation remains elusive with the more common internal alkenes. Here, we report the enantioselective, regioselective, and E/Z selective allylic oxidation of unactivated internal alkenes via a catalytic asymmetric hetero-ene reaction with a chalcogen-based oxidant. This method represents the first example of selectively converting unsymmetrical internal alkenes into allylic functionalized products with high stereoselectivity and regioselectivity. Stereospecific transformations of the multifunctional allylic oxidation products highlight the potential for rapidly converting internal alkenes into a broad range of enantioenriched structures that can be utilized in the synthesis of complex target molecules.

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“…In recent years, we– and others have reported that phosphoramidite ligands are compatible with Pd‐catalyzed allylic C−H functionalizations, some of which enable a diverse range of regio‐ and stereoselective allylic C−H alkylation reactions of 1,4‐dienes with various soft carbon nucleophiles (Scheme A). By means of DFT calculations, we identified that the geometry and coordination pattern of nucleophiles lead to different bond‐forming transition states and thereby determine the Z / E selectivites and regioselectivities (Scheme B) .…”

Section: Methodsmentioning

confidence: 99%

Nucleophile Coordination Enabled Regioselectivity in Palladium‐Catalyzed Asymmetric Allylic C−H Alkylation

et al. 2019

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Branched selectivity in asymmetric allylic C−H alkylation is enabled by using 2‐acylimidazoles as nucleophiles in the presence of a chiral phosphoramidite‐palladium catalyst. A wide range of terminal alkenes, including 1,4‐dienes and allylarenes, are nicely tolerated and provide chiral 2‐acylimidazoles in moderate to high yields and with high levels of regio‐, and enantio‐, and E/Z‐selectivities. Mechanistic studies using density‐functional theory calculations suggest a nucleophile‐coordination‐enabled inner‐sphere attack mode for the enantioselective carbon–carbon bond‐forming event.

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A New Class of Non-C₂-Symmetric Ligands for Oxidative and Redox-Neutral Palladium-Catalyzed Asymmetric Allylic Alkylations of 1,3-Diketones

Cited by 90 publications

References 81 publications

Mini-ISES identifies promising carbafructopyranose-based salens for asymmetric catalysis: Tuning ligand shape via the anomeric effect

Mini-ISES identifies promising carbafructopyranose-based salens for asymmetric catalysis: Tuning ligand shape via the anomeric effect

Catalytic allylic oxidation of internal alkenes to a multifunctional chiral building block

Nucleophile Coordination Enabled Regioselectivity in Palladium‐Catalyzed Asymmetric Allylic C−H Alkylation

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A New Class of Non-C2-Symmetric Ligands for Oxidative and Redox-Neutral Palladium-Catalyzed Asymmetric Allylic Alkylations of 1,3-Diketones

Cited by 90 publications

References 81 publications

Mini-ISES identifies promising carbafructopyranose-based salens for asymmetric catalysis: Tuning ligand shape via the anomeric effect

Mini-ISES identifies promising carbafructopyranose-based salens for asymmetric catalysis: Tuning ligand shape via the anomeric effect

Catalytic allylic oxidation of internal alkenes to a multifunctional chiral building block

Nucleophile Coordination Enabled Regioselectivity in Palladium‐Catalyzed Asymmetric Allylic C−H Alkylation

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A New Class of Non-C₂-Symmetric Ligands for Oxidative and Redox-Neutral Palladium-Catalyzed Asymmetric Allylic Alkylations of 1,3-Diketones