Solid Superbase‐Catalyzed Stereoselective 1,4‐Addition Reactions of Simple Amides in Batch and Continuous‐Flow Systems

Borah, Parijat; Yamashita, Yasuhiro; Kobayashi, Shū

doi:10.1002/adsc.201900364

Cited by 7 publications

(2 citation statements)

References 46 publications

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“…Moreover, the low reaction temperature (−78 °C or −50 °C) was pivotal for the high asymmetric induction. Except for the Grignard reagents, several other carbon-based nucleophiles were also employed in the catalytic asymmetric addition to α,β-unsaturated amides. , In 2015, the Kobayashi group uncovered an interesting catalytic asymmetric conjugate addition of simple amides to α,β-unsaturated amides . Notably, the catalyst in this reaction was generated from a potassium base and a macrocyclic chiral crown ether.…”

Section: Introductionmentioning

confidence: 99%

Copper(I)-Catalyzed Asymmetric 1,4-Conjugate Hydrophosphination of α,β-Unsaturated Amides

2020

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A catalytic asymmetric conjugate hydrophosphination of α,β-unsaturated amides is accomplished by virtue of the strong nucleophilicity of copper(I)-PPh 2 species, which provides an array of chiral phosphines bearing an amide moiety in high to excellent yields with excellent enantioselectivity. Furthermore, the dynamic kinetic resolution of unsymmetrical diarylphosphines (HPAr 1 Ar 2 ) is successfully carried out through the copper(I)-catalyzed conjugate addition to α,β-unsaturated amides, which affords P-chiral phosphines with good-to-high diastereoselectivity and high enantioselectivity. 1 H NMR studies show that the precoordination of HPPh 2 to copper(I)-bisphosphine complex is critical for the efficient deprotonation by Barton's Base. Moreover, the relative stability of the copper(I)-(R,R P )-TANIAPHOS complex in the presence of excessive HPPh 2 , confirmed by 31 P NMR studies, is pivotal for the high asymmetric induction, as the ligand exchange between bisphosphine and HPPh 2 would significantly reduce the enantioselectivity. At last, a double catalytic asymmetric conjugate hydrophosphination furnishes the corresponding product in high yield with high diastereoselectivity and excellent enantioselectivity, which is transformed to a chiral pincer palladium complex in moderate yield. This chiral palladium complex is demonstrated as an excellent catalyst in the asymmetric conjugate hydrophosphination of chalcone.

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Section: Introductionmentioning

confidence: 99%

Copper(I)-Catalyzed Asymmetric 1,4-Conjugate Hydrophosphination of α,β-Unsaturated Amides

2020

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“…Superbases were extensively used for catalyzing organic synthesis − and CO 2 capture, − but only a few attempts have been tried on the application of superbases in the CHC of lignin-related model compounds (LRMCs) − and heavy carbon resources. − Since the C-O bridged bonds (COBBs), such as ARCH 2 O-CH 2 AR, AROCH 2 AR, and ARO-AR, are the predominant COBBs in lignites, − insight into the CHCs of LRMCs, such as oxybis(methylene)dibenzene, ,, benzyloxybenzene, , and oxidibenzene , with COBBs, has become a powerful tool to understand the mechanisms for selectively cleaving COBBs and hydrogenating AR in lignites at molecular level. Among the COBBs, BRO-BR bond (360 kJ mol –1 ) in oxidibenzene is the strongest, , so the research gaining insight into the cleavage of COBB in oxidibenzene has attracted extensive attention.…”

Section: The Roles Of H– and H···h In The Chc Of Heavy Carbon Resourcesmentioning

confidence: 99%

Advances in Catalytic Hydroconversion of Typical Heavy Carbon Resources under Mild Conditions

Wei

Bai

et al. 2023

Energy Fuels

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Low-rank coals, biomass, and heavy petroleum are typical heavy carbon resources, which are currently not efficiently used, and many processes for the current use of the heavy carbon resources cause severe environmental pollution with very limited economic benefits even with a great deficit. Efficiently using the heavy carbon resources can greatly improve the environment and create huge economic benefits. The main difficulty in efficiently using the heavy carbon resources is the high content of aromatic rings (ARs) and heteroatoms in addition to the insoluble and complex macromolecular structures of the heavy carbon resources. Catalytic hydroconversion (CHC) includes catalytic hydrocracking and subsequent catalytic hydrofining. Many low-rank coals consist of macromolecular species, which are rich in bridged linkages connecting structural units, especially ARs, on which side chains are usually contained. Many ARs, bridged linkages, and side chains contain heteroatoms. Over a proper active catalyst, many bridged linkages and even some side chains can be cleaved, and many heteroatoms outside the ARs can be removed by the CHC under mild conditions to get soluble portions with relatively simple composition, facilitating subsequent separation to obtain pure chemicals, especially value-added products, such as condensed aromatics. The remaining economically inseparable species can be converted to liquid chemicals, especially nonsubstituted and alkyl-substituted cyclanes, by subsequent catalytic hydrofining. Catalysts and catalytically formed active hydrogen play crucial roles in the processes. Mainly based on our investigations, the related advances are reviewed in this work.

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Stable and Versatile Pd Precursors for the Preparation of Robust Pd Catalysts Under Continuous‐Flow

Sakurada,

Kobayashi,

Abe

et al. 2024

ChemSusChem

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The chemical and engineering communities require the development of versatile precursors that can be used to synthesize robust catalysts to achieve global sustainability. To meet this demand, we developed a new Pd precursor for incorporating fine Pd metal into supports in a highly efficient manner. An atmospherically stable Pd precursor (Pd‐80) was prepared by the thermally promoted aerobic oxidation of tetrakis(triphenylphosphine)palladium. The physical properties of Pd‐80 were investigated using NMR spectroscopy, SEM, XPS, solvent‐relaxation NMR spectroscopy, and dynamic light scattering (DLS) experiments. We also prepared a cordierite‐supported Pd catalyst (Pd/cordierite) by stirring Pd‐80 and cordierite powder in chloroform at room temperature. Pd/cordierite selectively catalyzes the hydrogenation of various reducible functional groups, including alkynes, azides, nitro groups, olefins, CO2Bn, N‐Cbz, O‐Bn, aromatic ketones, and styrene oxide, in continuous‐flow hydrogenation reactions. The Pd/cordierite‐catalyzed continuous‐flow hydrogenation of nitrobenzene derivatives afforded the corresponding anilines, with catalyst activity maintained for over 250 h of continuous operation and a turnover number (TON) of 61,090 recorded.

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Solid Superbase‐Catalyzed Stereoselective 1,4‐Addition Reactions of Simple Amides in Batch and Continuous‐Flow Systems

Abstract: This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record.

Cited by 7 publications

References 46 publications

Copper(I)-Catalyzed Asymmetric 1,4-Conjugate Hydrophosphination of α,β-Unsaturated Amides

Copper(I)-Catalyzed Asymmetric 1,4-Conjugate Hydrophosphination of α,β-Unsaturated Amides

Advances in Catalytic Hydroconversion of Typical Heavy Carbon Resources under Mild Conditions

Stable and Versatile Pd Precursors for the Preparation of Robust Pd Catalysts Under Continuous‐Flow

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