Enantioselective Inverse Electron Demand (3 + 2) Cycloaddition of Palladium-Oxyallyl Enabled by a Hydrogen-Bond-Donating Ligand

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(2), С. 1038 - 1045

Опубликована: Янв. 6, 2021

Cycloaddition reactions between oxyallyl cations and alkenes are important transformations for the construction of ring systems. Although (4 + 3) cycloaddition well-developed, (3 2) cycloadditions remain rare, an asymmetric version has not yet been developed. Moreover, because highly electrophilic, only electron-rich olefins can be used as partners. We herein report a method enantioselective palladium-oxyallyl species electron-deficient nitroalkenes. This transformation was enabled by rationally designed hydrogen-bond-donating ligand (FeUrPhos) proceeded via inverse electron demand pathway. Using this method, we could assemble cyclopentanones with up to three contiguous stereocenters high enantioselectivity good excellent diastereoselectivity.

Язык: Английский

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Recent advances in annulation reactions based on zwitterionic π-allyl palladium and propargyl palladium complexes

Organic Chemistry Frontiers, Год журнала: 2021, Номер 8(13), С. 3475 - 3501

Опубликована: Янв. 1, 2021

Carbocyclic and heterocyclic compounds could be constructed through the palladium-catalyzed annulation reactions of zwitterionic π-allyl palladium or propargyl complexes with unsaturated electrophiles.

Язык: Английский

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A Palladium Complex as an Asymmetric π-Lewis Base Catalyst for Activating 1,3-Dienes

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(12), С. 4809 - 4816

Опубликована: Март 18, 2021

Here we report that palladium(0) complexes can coordinate in a η2 fashion to 1,3-dienes and significantly raise the energy of their highest occupied molecular orbital (HOMO) by donating electrons from d-orbitals empty antibonding orbitals double bonds (π*) via back-bonding. Thus, uncoordinated bond, as more reactive partner on basis principle vinylogy, directly attack imines, furnishing formal hydrodienylation reaction enantioselectively. A chemoselective cascade vinylogous addition/allylic alkylation difunctionalization process between imines with nucleophilic group is also compatible, trapping situ formed π-allylpalladium species after initial ene addition. This π-Lewis base catalytic mode, featuring simple η2coordination, activation, compatibility both conjugated neutral polyenes electron-deficient polyenes, elucidated control experiments density functional theory (DFT) calculations.

Язык: Английский

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Recent advances of Pd-π-allyl zwitterions in cycloaddition reactions

Chinese Chemical Letters, Год журнала: 2023, Номер 34(11), С. 108401 - 108401

Опубликована: Март 30, 2023

Язык: Английский

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Sadphos as Adaptive Ligands in Asymmetric Palladium Catalysis

Accounts of Chemical Research, Год журнала: 2024, Номер unknown

Опубликована: Янв. 31, 2024

ConspectusPalladium catalysis, as one of the most important strategies in asymmetric synthesis, has continuously attracted attention organic chemists. With development chiral ligands, increasingly challenging reactions and substantial progress catalysis are being realized.Since 2014, we have focused on exploiting a series sulfinamide phosphine ligands called "Sadphos," including Ming-Phos, Xu-Phos, Xiao-Phos, Xiang-Phos, TY-Phos, PC-Phos, GF-Phos, WJ-Phos. These can be easily prepared two to four steps using commercial materials. new types shown remarkable performance transition-metal-catalyzed reactions, especially Pd-catalyzed transformations. X-ray diffraction analysis, mechanistic studies, density functional theory calculations revealed that Sadphos coordinate with Pd0 PdII species Pd0/P, Pd0/P,S, or PdII/P,O modes.This Account summarizes our recent efforts toward palladium-catalyzed enantioselective ligands. were found privileged very crucial promote by increasing reactivity enantioselectivity. Ming-Phos is an effective ligand coupling intramolecular Heck providing highly trisubstituted allenes, axially anilides, gem-diarylmethine silanes, disubstituted dihydroisoquinolinones. Incorporation electron-rich cyclohexyl group moiety afforded which showed unique effect transformations, reductive Heck, dearomative Mizoroki–Heck, tandem Heck/Suzuki coupling, carboiodination, carboamination, cross-coupling reactions. Using similar strategy, synthesized more electron–rich TY-Phos Xiang-Phos bearing t-butyl 1-adamantyl at P atoms, respectively. Regarding stereoelectronic features, these characteristic best choice satisfy requirements fluoroarylation gem-difluoroalkenes, intermolecular α-arylation aldehydes, carboetherification alkenyl oximes, carboheterofunctionalization 2,3-dihydrofurans. Compared aforementioned attractive features high nucleophilicity originating from CH2PPh2 ortho-substituent side aryl ring, presumably responsible for its efficiency. The Pd/Xiao-Phos catalyst system shows good secondary oxides, affording P-stereogenic products multiple molecular skeletons. modification basic backbone introducing xanthene skeleton motivated us design synthesize monophosphines, named PC-Phos GF-Phos. various arylation sulfenate anions, denitrogenative cyclization benzotriazoles, dearomatization indoles. practicability GF-Phos was validated three-component N-tosylhydrazones, halides, terminal alkynes, well N-tosylhydrazones vinyl iodides pendent amines. In addition, ferrocene-derived WJ-Phos employed Suzuki–Miyaura reaction, biaryl monophosphine oxides excellent enantiomeric excesses.

Язык: Английский

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Feeble Single-Atom Pd Catalysts for H₂ Production from Formic Acid

ACS Applied Materials & Interfaces, Год журнала: 2024, Номер 16(8), С. 10251 - 10259

Опубликована: Янв. 19, 2024

Single-atom catalysts are thought to be the pinnacle of catalysis. However, for many reactions, their suitability has yet unequivocally proven. Here, we demonstrate why single Pd atoms (PdSA) not catalytically ideal generating H2 from formic acid as a carrier. We loaded PdSA on three silica substrates, mesoporous silicas functionalized with thiol, amine, and dithiocarbamate functional groups. The catalytic activity amino-functionalized (SiO2–NH2/PdSA) was far higher than that thiol-based (SiO2–S–PdSA SiO2–NHCS2–PdSA), while single-atom stability SiO2–NH2/PdSA against aggregation after first cycle weakest. In this case, boosted reaction yield. Our experiments calculations in loosely binds amine This leads limited charge transfer groups causes high aggregability activity. According density calculations, loose binding between N most Pd's 4d electrons SiO2 remain close Fermi level labile chemically thiol group, resulting strong hybridization S, pulling states deeper into conduction band away level. Consequently, fewer were available

Язык: Английский

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Palladium-Catalyzed Enantioselective Cycloadditions of Aliphatic 1,4-Dipoles: Access to Chiral Cyclohexanes and Spiro [2.4] heptanes

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(43), С. 18628 - 18636

Опубликована: Окт. 14, 2020

Design and exploration of new intermediates for chemo-, regio-, stereoselective cycloadditions remain a formidable challenge in modern organic synthesis. Compared to the well-developed 1,3-dipolar cycloadditions, Pd-catalyzed1,4-dipolar are generally limited specialized substrates due inherent nature thermodynamically driven intramolecular transformations undesired isomerizations. Herein, we demonstrate use ligated palladium catalysts control modulate intermolecular reactivity aliphatic 1,4-dipoles, enabling two distinctive cycloaddition pathways with broad scope acceptors. This atom-economic process also features an eco-friendly situ deprotonation strategy generate corresponding active palladium-mediated dipoles. Overall, diverse array chiral 6-membered rings spiro [2.4] heptanes were prepared high yield selectivity. In addition, unexpected property cyano-stabilized carbanions was discovered investigated, which can be useful designing predicting future transformations.

Язык: Английский

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Palladium-Catalyzed Asymmetric Tandem Denitrogenative Heck/Tsuji–Trost of Benzotriazoles with 1,3-Dienes

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(33), С. 13010 - 13015

Опубликована: Авг. 17, 2021

The asymmetric denitrogenative cycloaddition has emerged as a powerful tool to build chiral aza-heterocyles. However, only one example of benzotriazole with unsaturated hydrocarbons been explored so far, because the ring-opening generate α-imino metal carbenoid species is thermodynamically unfavorable process. We herein report an efficient benzotriazoles cyclic and acyclic 1,3-dienes enabled by Pd sulfonamide phosphine ligand. A variety substituted hexahydrocarbazoles indolines were delivered in good yields high ee values. Interestingly, pair enantiomers could be obtained use Xu1 PC2 same absolute configuration. synthetic utilities optically active also showcased.

Язык: Английский

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Lewis-Acid-Promoted Ligand-Controlled Regiodivergent Cycloaddition of Pd-Oxyallyl with 1,3-Dienes: Reaction Development and Origins of Selectivities

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(9), С. 3595 - 3603

Опубликована: Фев. 25, 2021

For nearly 30 years, considerable research effort has been focused on the development of methods for catalytic (3 + 2) cycloaddition reactions palladium-oxyallyl species with alkenes. However, because C–O bond formation is kinetically favored, cycloadditions achieved to date have involved reductive elimination. We herein report a method lithium triflate-promoted 1,3-dienes that proceed via pathway terminated C–C give five-membered carbocycle. Coordination ion alkoxide moiety disrupts elimination and forms metal-enolate tethered π-allyl-Pd. The π-allyl-Pd then accepts intramolecular allylic attack from enolate form carbocyclic products. Furthermore, by tuning steric properties palladium ligand, we could also accomplish competing (4 3) cycloadditions, thus this provides regiodivergent access both cyclopentanones cycloheptanones. reaction mechanism was investigated DFT calculation origins regioselectivities were rationalized.

Язык: Английский

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Palladium-Catalyzed Enantioselective Cycloaddition of Carbonylogous 1,4-Dipoles: Efficient Access to Chiral Cyclohexanones

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(52), С. 21645 - 21650

Опубликована: Дек. 18, 2020

A novel palladium-mediated carbonylogous 1,4-dipole was developed by in situ deprotonation. By using our own-developed C2-unsymmetric phosphoramidite as supporting ligand, this dipole applied to the asymmetric synthesis of chiral cyclohexanones via a catalytic [4+2] cycloaddition. Electron-deficient allylic carbonate used generate highly reactive dipoles for first time, and diverse array stable precursors explored elaboration cyclohexanones. general mechanism reaction process stereochemical outcome proposed, which can be useful designing predicting future transformation.

Язык: Английский

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