Xiaoyan Hou

Bio: Xiaoyan Hou is an academic researcher from University of Göttingen. The author has contributed to research in topics: Enantioselective synthesis & Axial chirality. The author has an hindex of 3, co-authored 8 publications receiving 26 citations.

Ruthenaelectro-Catalyzed Domino Three-Component Alkyne Annulation for Expedient Isoquinoline Assembly.

Abstract: The electrochemical three-component assembly of isoquinolines has been accomplished by ruthenaelectro-catalyzed C-H/N-H functionalization. The robustness of the electrocatalysis was reflected by an ample substrate scope, an efficient electrooxidation, and an operationally friendly procedure. The isolation of key intermediates and detailed mechanistic studies, including unprecedented cyclovoltammetric analysis of a seven-membered ruthenacycle, provided support for an unusual ruthenium(II/III/I) regime.

Enantioselective palladaelectro-catalyzed C-H olefinations and allylations for N-C axial chirality.

Abstract: Enantioselective palladaelectro-catalyzed C–H alkenylations and allylations were achieved with easily-accessible amino acids as transient directing groups. This strategy provided access to highly enantiomerically-enriched N–C axially chiral scaffolds under exceedingly mild conditions. The synthetic utility of our strategy was demonstrated by a variety of alkenes, while the versatility of our approach was reflected by atroposelective C–H allylations. Computational studies provided insights into a facile C–H activation by a seven-membered palladacycle.

Rhoda‐Electrocatalyzed Bimetallic C–H Oxygenation by Weak O‐Coordination

Abstract: Rhodium-electrocatalyzed arene C-H oxygenation by weakly O- coordinating amides and ketones have been established by bimetallic electrocatalysis. Likewise, diverse dihydrooxazinones were selectively accessed by the judicious choice of current, enabling twofold C-H functionalization. Detailed mechanistic studies by experiment, mass spectroscopy and cyclovoltammetric analysis provided support for an unprecedented electrooxidation-induced C-H activation by a bimetallic rhodium catalysis manifold.

A Strategy for Site- and Chemoselective C-H Alkenylation through Osmaelectrooxidative Catalysis.

Abstract: Herein, we disclose osmaelectrocatalyzed C-H activations that set the stage for electrooxidative alkyne annulations by benzoic acids. The osmium electrocatalysis enables site- and chemoselective electrooxidative C-H activations with unique levels of selectivity. The isolation of unprecedented osmium(0) and osmium(II) intermediates, along with crystallographic characterization and analyses by spectrometric and spectroscopic in operando techniques delineate a synergistic osmium redox catalyst regime. Detailed mechanistic studies revealed a facile C-H cleavage, which allows for an ample substrate scope, providing provide robust and user-friendly access to annulated heterocycles.

Electrocatalysis as an enabling technology for organic synthesis.

Abstract: Electrochemistry has recently gained increased attention as a versatile strategy for achieving challenging transformations at the forefront of synthetic organic chemistry. Electrochemistry's unique ability to generate highly reactive radical and radical ion intermediates in a controlled fashion under mild conditions has inspired the development of a number of new electrochemical methodologies for the preparation of valuable chemical motifs. Particularly, recent developments in electrosynthesis have featured an increased use of redox-active electrocatalysts to further enhance control over the selective formation and downstream reactivity of these reactive intermediates. Furthermore, electrocatalytic mediators enable synthetic transformations to proceed in a manner that is mechanistically distinct from purely chemical methods, allowing for the subversion of kinetic and thermodynamic obstacles encountered in conventional organic synthesis. This review highlights key innovations within the past decade in the area of synthetic electrocatalysis, with emphasis on the mechanisms and catalyst design principles underpinning these advancements. A host of oxidative and reductive electrocatalytic methodologies are discussed and are grouped according to the classification of the synthetic transformation and the nature of the electrocatalyst.

Atropisomers beyond the C–C axial chirality: Advances in catalytic asymmetric synthesis

Abstract: Atropisomers beyond the C–C axis (denoted as X–Y herein) are important addition to the repertoire of axially chiral compounds, which have received much attention in recent years. Compared with conventional C–C axial chirality around biaryl and olefin axes, atropisomerism portrayed by C–N, C–O, C–B, or N–N bond was deemed to be challenging due to the relatively low rotational barriers. However, the intrinsic shorter bond length and electron-repelling effect lead to a congested hetero X–Y axis, resulting in stable axially chiral frameworks. The past two decades, especially the past few years have witnessed a rapid progress of this emerging area. A range of catalytic atroposelective approaches have been reported for the efficient synthesis of these challenging skeletons. The X–Y axially chiral compounds are valuable molecules, and they may be used as new ligands or catalysts in asymmetric catalysis or evaluated for their potential biological activities. We believe that the chemistry of atropisomers beyond C–C axial chirality will be forthcoming and blooming in the near future, taking up an important position in organic chemistry and beyond. Atropisomers beyond the C–C axis (denoted as X–Y herein) are important addition to the repertoire of axially chiral compounds, which have received much attention in recent years. Compared with conventional C–C axial chirality around biaryl and olefin axes, atropisomerism portrayed by C–N, C–O, C–B, or N–N bond was deemed to be challenging due to the relatively low rotational barriers. However, the intrinsic shorter bond length and electron-repelling effect lead to a congested hetero X–Y axis, resulting in stable axially chiral frameworks. The past two decades, especially the past few years have witnessed a rapid progress of this emerging area. A range of catalytic atroposelective approaches have been reported for the efficient synthesis of these challenging skeletons. The X–Y axially chiral compounds are valuable molecules, and they may be used as new ligands or catalysts in asymmetric catalysis or evaluated for their potential biological activities. We believe that the chemistry of atropisomers beyond C–C axial chirality will be forthcoming and blooming in the near future, taking up an important position in organic chemistry and beyond.

Stereoselective construction of atropisomers featuring a C–N chiral axis

Abstract: Atropisomeric C–N compounds belong to an important class of axially chiral compounds. However, whereas the asymmetric synthesis of biaryl atropisomers have been well established, general and efficient strategies to access single enantiomers of C–N atropisomers are still rare. Until recently, innovative methods have been developed, providing new opportunities for the highly stereoselective synthesis of this vital class of atropisomers. Herein, we comprehensively summarize the development in this emerging field and give some insights into future advance. Emphasis is placed on the synthetic strategies. Atropisomeric C–N compounds belong to an important class of axially chiral compounds. Herein, we comprehensively summarize the development in this emerging field and give some insights into future advance.

Asymmetric Synthesis of Axially Chiral C−N Atropisomers

Abstract: Abstract Molecules with restricted rotation around a single bond or atropisomers are found in a wide number of natural products and bioactive molecules as well as in chiral ligands for asymmetric catalysis and smart materials. Although most of these compounds are biaryls and heterobiaryls displaying a C−C stereogenic axis, there is a growing interest in less common and more challenging axially chiral C−N atropisomers. This review offers an overview of the various methodologies available for their asymmetric synthesis. A brief introduction is initially given to contextualize these axially chiral skeletons, including a historical background and examples of natural products containing axially chiral C−N axes. The preparation of different families of C−N based atropisomers is then presented from anilides to chiral five‐ and six‐membered ring heterocycles. Special emphasis has been given to modern catalytic asymmetric strategies over the past decade for the synthesis of these chiral scaffolds. Applications of these methods to the preparation of natural products and biologically active molecules will be highlighted along the text.

Green strategies for transition metal-catalyzed C–H activation in molecular syntheses

Abstract: Transition metal catalyzed C–H activation has surfaced as a powerful tool to improve the efficacy of molecular synthesis. Last two decades have witnessed a considerable progress in the activation of otherwise inert C–H bonds. However, during recent years, focus has shifted to address rising concerns to achieve high levels of resource economy in molecular syntheses. Herein, we discuss the advent and recent emerging strategies to improve the sustainability and environmentally benign nature of C–H activation manifolds.