Palladium(0) π-Lewis Base Catalysis: Concept and Development

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(10), P. 6422 - 6437

Published: March 1, 2024

The development of a new catalytic strategy plays vital role in modern organic chemistry since it permits bond formation an unprecedented and more efficient manner. Although the application preformed metal complexes as π-base-activated reagents have enabled diverse transformations elegantly, concept by directly utilizing transition metals π-Lewis base catalysts remain underdeveloped, especially field asymmetric catalysis. Here, we outline our perspective on discovery palladium(0) catalyst, which is capable increasing highest occupied molecular orbital (HOMO) energy both electron-neutral electron-deficient 1,3-dienes 1,3-enynes upon flexible η2-complexes formed situ resultant π-backdonation. Thus, fruitful carbon–carbon-forming reactions with electrophiles can be achieved enantioselectively vinylogous addition pattern, conceptually different from classical oxidative cyclization mechanism. Emphasis will given to mechanism elucidation, features, reaction design together further this emerging field.

Language: Английский

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Palladium‐Catalyzed Inverse and Normal Dehydrogenative Aza‐Morita–Baylis–Hillman Reactions with γ,δ‐Unsaturated Compounds

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(23)

Published: April 3, 2023

σ-Lewis base-catalyzed regio- and enantioselective aza-Morita-Baylis-Hillman (MBH) reaction of α,β,γ,δ-unsaturated systems remains a challenge due to the intrinsic covalent activation mode. Here we demonstrate that Pd0 complex can mediate dehydrogenative γ,δ-unsaturated compounds give corresponding electron-poor dienes, which further undergo δ-regioselective umpolung Friedel-Crafts-type addition imines via auto-tandem -π-Lewis base catalysis. After β-H elimination in situ formed PdII -complexes, unprecedented chemically inverse aza-MBH-type adducts are finally furnished with fair outstanding enantioselectivity, diversity functional groups both ketimine aldimine acceptors be well tolerated. Moreover, switchable α-regioselective normal also realized by tuning catalytic conditions, whereas moderate good enantioselectivity low excellent Z/E-selectivity is attained.

Language: Английский

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Enantioselective Cross-[4 + 2]-Cycloaddition/Decarboxylation of 2-Pyrones by Cooperative Catalysis of the Pd(0)/NHC Complex and Chiral Phosphoric Acid

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(10), P. 6936 - 6946

Published: Feb. 28, 2024

Here, we describe a cooperative Pd(0)/chiral phosphoric acid catalytic system that allows us to realize the first chemo-, regio-, and enantioselective sequential cross-[4 + 2]-cycloaddition/decarboxylation reaction between 2-pyrones unactivated acyclic 1,3-dienes. The key success of this transformation is utilization an achiral N-heterocyclic carbene (NHC) as ligand newly developed chiral cocatalyst. Experimental investigations computational studies support idea Pd(0)/NHC complex acts π-Lewis base increase nucleophilicity 1,3-dienes via η2 coordination, while simultaneously increases electrophilicity by hydrogen bonding. By synergistic catalysis, 2]-cycloaddition decarboxylation proceeds efficiently, enabling preparation wide range vinyl-substituted 1,3-cyclohexadienes in good yields enantioselectivities. synthetic utility demonstrated transformations product various valuable six-membered carbocycles.

Language: Английский

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Metal π-Lewis Base Activation Model in Pd-Catalyzed Hydroamination of Amines and 1,3-Dienes

Chemical Science, Journal Year: 2023, Volume and Issue: 14(17), P. 4597 - 4604

Published: Jan. 1, 2023

As a general mechanism proposal, Pd(ii)-H migration insertion process is not able to well explicate the Pd-catalyzed hydroamination of amines and 1,3-dienes. Here we demonstrate that 1,3-dienes form electron-neutral HOMO-raised η2-complexes with Pd(0) via π-Lewis base activation, which undergoes protonation variety acidic sources, such as Brønsted acids, Lewis acid-activated indazoles, Pd(ii) pre-catalyst triggered ammonium salts. The resultant π-allyl palladium complexes undergo amination reaction give final observed products. FMO NPA analyses have revealed nature mediated activation calculation results show pathway more favourable than species involved one in different reactions. Further control experiments corroborated our mechanistic an efficient was developed.

Language: Английский

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Facile Synthesis of Quinoline-Substituted 3-Hydroxy-2-oxindoles and 3-Amino-2-oxindoles via a Palladium-Catalyzed Cascade Intramolecular Cyclization/Intermolecular Nucleophilic Addition Reaction

The Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 89(5), P. 3413 - 3418

Published: Feb. 20, 2024

An efficient cascade intramolecular cyclization/intermolecular nucleophilic addition reaction of allenyl benzoxazinone with isatin or isatin-derived ketimine has been established by using Pd0-π-Lewis base catalysis. A series 3-hydroxy-2-oxindoles and 3-amino-2-oxindoles quaternary carbon atoms at the C3 position were synthesized in good yields under mild conditions through this protocol.

Language: Английский

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Palladium-Catalyzed Asymmetric Cascade Intramolecular Cyclization/Intermolecular Michael Addition Reaction of Allenyl Benzoxazinones with 1-Azadienes

Organic Letters, Journal Year: 2022, Volume and Issue: 24(51), P. 9442 - 9446

Published: Dec. 20, 2022

We herein designed and synthesized allenyl benzoxazinones of a novel type, which were then involved in Pd-catalyzed asymmetric cascade intramolecular cyclization/intermolecular Michael addition reaction with 1-azadienes. A broad range chiral C2-functionalized quinoline derivatives afforded moderate to good yields (up 93%) high enantioselectivities 93% ee) this reaction.

Language: Английский

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Elucidating the mechanism and regioselectivity of phosphine-catalyzed transformation of MBH carbonate

New Journal of Chemistry, Journal Year: 2023, Volume and Issue: 47(35), P. 16636 - 16642

Published: Jan. 1, 2023

A general mechanistic map of the PPh 3 -catalyzed transformation reaction MBH carbonate has been theoretically studied and NCI ELF analyses are performed to disclose origins selectivities role catalyst, respectively.

Language: Английский

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Palladium(0) and Brønsted Acid Co‐catalyzed Enantioselective Hydro‐Cyclization of 2,4‐Dienyl Hydrazones and Oximes

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(44)

Published: Aug. 6, 2024

Abstract The transition metal‐catalyzed asymmetric hydro‐functionalization of 1,3‐dienes has been well explored, but most reactions focus on electron‐neutral substrates in an intermolecular manner. Here we first demonstrate that readily available 2,4‐dienyl hydrazones and oximes can be efficiently utilized the hydro‐cyclization reaction under co‐catalysis a Brønsted acid chiral palladium complex, furnishing multifunctional dihydropyrazones dihydroisoxazoles, respectively. Diverse substitution patterns for both types electron‐deficient diene compounds are tolerated, corresponding heterocycles were generally constructed with moderate to excellent enantioselectivity, which elaborated access products higher molecular complexity diversity. Control experiments density functional theory calculations support α‐regioselective protonation dienyl by concurrent π‐Lewis base activation Pd 0 complex is energetically favoured formation active π‐allylpalladium intermediates, outer‐sphere allylic amination or etherification mode adopted deliver observed cyclized enantioselectively.

Language: Английский

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Theoretical Insight into the Palladium-Catalyzed Prenylation and Geranylation of Oxindoles with Isoprene

Inorganic Chemistry, Journal Year: 2024, Volume and Issue: 63(11), P. 4855 - 4866

Published: March 6, 2024

This work presents a comprehensive mechanistic study of the ligand-controlled palladium-catalyzed prenylation (with C5 added) and geranylation C10 reactions oxindole with isoprene. The calculated results indicate that bis-phosphine ligand monophosphine fundamentally share common mechanism. mechanism involves formation two crucial species: η3-allyl-Pd(II) cation an carbon anion. Furthermore, necessitate assistance second molecule, which serves as Brønsted acid, providing proton to generate nitrogen anion then acts base, abstracting C–H from another molecule form These details differ significantly those proposed in experimental work. present calculations do not support presence Pd–H species η3, η3-diallyl-Pd(II) intermediate, were previously suggested experiments. theoretical rationalize finding favors oxindole, while enables oxindole.

Language: Английский

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Substrate-Controlled Diversity-Oriented Synthesis of Novel Polycyclic Frameworks via [4 + 2] and [3 + 2] Annulations of Ninhydrin-Derived MBH Adducts with 3,4-Dihydroisoquinolines

Molecules, Journal Year: 2023, Volume and Issue: 28(19), P. 6761 - 6761

Published: Sept. 22, 2023

Substrate-controlled diversity-oriented synthesis of polycyclic frameworks via [4 + 2] and [3 annulations between ninhydrin-derived Morita-Baylis-Hillman (MBH) adducts 3,4-dihydroisoquinolines under similar reaction conditions have been developed. The provides a series novel structurally complex spiro multi heterocyclic skeletons in good yields (up to 87% 90%, respectively) with excellent diastereoselectivities >25:1 dr). In particular, the switchable annulation reactions are controlled by tuning hydroxyl protecting group on MBH adduct deliver structural diverse spiro[indene-2,2'-[1,3]oxazino[2,3-a]isoquinoline] spiro[indene-2,1'-pyrrolo[2,1-a]isoquinoline], respectively. Furthermore, relative configuration chemical structure two kinds cycloadducts were confirmed through X-ray diffraction analysis.

Language: Английский

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