Hyper-Crosslinked Porous Chiral Phosphoric Acids: Robust Solid Organocatalysts for Asymmetric Dearomatization Reactions

Huang, Xian-Yun; Zheng, Qingshu; Zou, Lei-Ming; Gu, Qianqun; Tu, Tao; You, Shu‐Li

doi:10.1021/acscatal.2c00397

Cited by 27 publications

(8 citation statements)

References 94 publications

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“…Very recently, Gu, Tu, You, and co-workers reported the synthesis and application of porous chiral phosphoric acids, such as the BINOL-derived compound CPA-4 , for the enantioselective transfer hydrogenation of a variety of 2-phenylquinolines 2 in the presence of Hantzsch ester HEH-4 (Scheme ). The porous heterogeneous catalyst CPA-4 could be recovered via centrifugation and reused up to 10 times without significant loss in terms of yield and enantioselectivity, which greatly enhances the synthetic utility of this methodology.…”

Section: Hydroboration Hydrosilylation and Reduction Reactionsmentioning

confidence: 99%

Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines

Escolano,

Gaviña,

Alzuet-Piña

et al. 2024

Chem. Rev.

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Dearomatization reactions have become fundamental chemical transformations in organic synthesis since they allow for the generation of three-dimensional complexity from two-dimensional precursors, bridging arene feedstocks with alicyclic structures. When those processes are applied to pyridines, quinolines, and isoquinolines, partially or fully saturated nitrogen heterocycles are formed, which are among the most significant structural components of pharmaceuticals and natural products. The inherent challenge of those transformations lies in the low reactivity of heteroaromatic substrates, which makes the dearomatization process thermodynamically unfavorable. Usually, connecting the dearomatization event to the irreversible formation of a strong C−C, C− H, or C−heteroatom bond compensates the energy required to disrupt the aromaticity. This aromaticity breakup normally results in a 1,2-or 1,4-functionalization of the heterocycle. Moreover, the combination of these dearomatization processes with subsequent transformations in tandem or stepwise protocols allows for multiple heterocycle functionalizations, giving access to complex molecular skeletons. The aim of this review, which covers the period from 2016 to 2022, is to update the state of the art of nucleophilic dearomatizations of pyridines, quinolines, and isoquinolines, showing the extraordinary ability of the dearomative methodology in organic synthesis and indicating their limitations and future trends.

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Section: Hydroboration Hydrosilylation and Reduction Reactionsmentioning

confidence: 99%

Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines

Escolano,

Gaviña,

Alzuet-Piña

et al. 2024

Chem. Rev.

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“…In 2022, You et al successfully achieved the synthesis of chiral phosphoric acid 25 (5 mol%) through the utilization of a heterogeneous porous BINOL and the ‘weaving’ strategy ( Scheme 25 ). 101 By introducing an anthracene group at the 3,3′-position of BINOL, a three-dimensional environment was created, facilitating the formation of highly cross-linked networked PCPAs as controllable connecting units. These PCPAs exhibited remarkable catalytic activity in the asymmetric transfer hydrogenation of 2-phenylquinoline and the dearomatization of β-naphthol with DEAD, resulting in an impressive yields of 98% and a high ee of 99%.…”

Section: Insoluble Carrier Supported Catalystmentioning

confidence: 99%

Application of chiral recyclable catalysts in asymmetric catalysis

Han,

Ren,

Zhang

et al. 2024

RSC Adv.

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“…In 2022, the You group reported another copolymerization approach using external cross-linkers and applied their catalysts in an asymmetric transfer hydrogenation and dearomatization of β-naphthols, however, under batch conditions only. 43 …”

Section: Introductionmentioning

confidence: 99%

General, Modular Access toward Immobilized Chiral Phosphoric Acid Catalysts and Their Application in Flow Chemistry

Laue,

Schneider,

Gebauer

et al. 2024

ACS Catal.

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Chiral phosphoric acids (CPAs) are among the most frequently used organocatalysts, with an ever-increasing number of applications. However, these catalysts are only obtained in a multistep synthesis and are poorly recyclable, which significantly deteriorates their environmental and economic performance. We herein report a conceptually different, general strategy for the direct immobilization of CPAs on a broad scope of solid supports including silica, polystyrene, and aluminum oxide. Solid-state catalysts were obtained in high yields and thoroughly characterized with elemental analysis by inductively coupled plasma-optical emission spectrometry (ICP-OES), nitrogen sorption measurements, thermogravimetric analysis, scanning transmission electron microscopy/energy-dispersive X-ray spectroscopy (STEM/EDX) images, and solid-state NMR spectroscopy. Further, the immobilized catalysts were applied to a variety of synthetically valuable, highly stereoselective transformations under batch and flow conditions including transfer hydrogenations, a Friedlander condensation/transfer hydrogenation sequence, and Mannich reactions under cryogenic flow conditions. Generally, high yields and stereoselectivities were observed along with robust catalyst stability and reusability. After being used for 10 runs under batch conditions, no loss of selectivity or catalytic activity was observed. Under continuous-flow conditions, the heterogeneous system was in operation for 19 h and the high enantioselectivity remained unchanged throughout the entire process. We expect our approach to extend the applicability of CPAs to a higher level, with a focus on flow chemistry and a more environmentally friendly and resource-efficient use of these powerful catalysts.

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Hyper-Crosslinked Porous Chiral Phosphoric Acids: Robust Solid Organocatalysts for Asymmetric Dearomatization Reactions

Cited by 27 publications

References 94 publications

Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines

Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines

Application of chiral recyclable catalysts in asymmetric catalysis

General, Modular Access toward Immobilized Chiral Phosphoric Acid Catalysts and Their Application in Flow Chemistry

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