Robby Vroemans

Nickel catalysis has significantly contributed to ketones synthesis from carboxylic acid derivatives (CADs) over last five decades. Stabilization of acyl-nickel complexes and methods for stoichiometric to catalytic ratio of nickel have successfully achieved. Remarkably, acid chlorides and amides have extensively participated, and Ni(0) catalytic systems have predominantly contributed comparatively Ni(II) catalysts in ketone manufacturing process using CADs.

Abstract

Nickel catalysis in cross-coupling reaction of carboxylic acid derivatives (CADs) with various coupling partners to access ketones has grown steadily in last five decades and substantially contributed to this area. These synthetic protocols have afforded various unique privileges: 1) robust approach to access ketones in a stereo defined manner; 2) reduced byproduct formation; 3) broad substrate scope with high functional group tolerance and 4) avoids direct use of fatal carbon monoxide. Herein, an overview of acyl-nickel complexes reactivity, major mechanistic pathways in ketones synthesis, rational aspects of nickel catalysis with CADs and highlights of synthetic applications will be described in detail. The main objective of this review is demonstration of historical development of nickel catalysis with CADs to access ketones from year 1970 to 2020 and introductory remarks of current state of work progress in this area.

Recent advances and challenges in the application of single-atom nanozymes for biosensing detection and biomedical therapy are summarized in this review.

Abstract

Nanozymes have received extensive attention in the fields of sensing and detection, medical therapy, industry, and agriculture thanks to the combination of the catalytic properties of natural enzymes and the physicochemical properties of nanomaterials, coupled with superior stability and ease of preparation. Despite the promise of nanozymes, conventional nanozymes are constrained by their oversized size and low catalytic capacity in sophisticated practical application environments. single-atom nanozymes (SAzymes) were characterized as nanozymes with high catalytic efficiency by uniformly distributed single atoms as catalysis sites, thus effectively addressing the defects of conventional nanozymes. This paper reviews the activity improvement scheme and catalytic mechanism of SAzymes and highlights the latest research progress of SAzymes in the fields of biomedical sensing and therapy. Eventually, the challenges and future directions of SAzymes are discussed in this paper.

A ligand-controlled 1,4-palladium shift onto an N-methyl group enables the construction of C−C bonds in a remote position to the initial C−Br bond, leading to valuable isoindoline and β-lactam products. The reaction proceeds via trapping of the σ-alkylpalladium intermediate by C−H activation at another nitrogen substituent.

Abstract

In the past years, Pd⁰-catalyzed C(sp³)−H activation provided efficient and step-economical methods to synthesize carbo- and heterocycles via direct C(sp²)−C(sp³) bond formation. We report herein that a 1,4-Pd shift allows access to N-heterocycles which are difficult to build via a direct reaction. It is shown that o-bromo-N-methylanilines undergo a 1,4-Pd shift at the N-methyl group, followed by intramolecular trapping by C(sp²)−H or C(sp³)−H activation at another nitrogen substituent and remote C−C bond formation to generate biologically relevant isoindolines and β-lactams. The product selectivity is influenced by the employed ligand, with NHCs favoring the product of remote C−C coupling against products arising from direct C−C coupling and N-demethylation.

This review emphasized the composition and characteristics of recent development on g-C₃N₄ based materials. Various fabrication methodologies for g-C₃N₄ and g-C₃N₄-based materials were focused and evaluated in this report. Methods for enhancing the photocatalytic performance of g-C₃N₄ based materials. Most important aspects were extensively explored.

Abstract

Being one of the foremost enticing and intriguing innovations, heterogeneous photocatalysis has also been used to effectively gather, transform, and conserve sustainable sun‘s radiation for the production of efficient and clean fossil energy as well as a wide range of ecological implications. The generation of solar fuel-based water splitting and CO₂ photoreduction is excellent for generating alternative resources and reducing global warming. Developing an inexpensive photocatalyst can effectively split water into hydrogen (H₂), oxygen (O₂) sources, and carbon dioxide (CO₂) into fuel sources, which is a crucial problem in photocatalysis. The metal-free g-C₃N₄ photocatalyst has a high solar fuel generation potential. This review covers the most recent advancements in g-C₃N₄ preparation, including innovative design concepts and new synthesis methods, and novel ideas for expanding the light absorption of pure g-C₃N₄ for photocatalytic application. Similarly, the main issue concerning research and prospects in photocatalysts based g-C₃N₄ was also discussed. The current dissertation provides an overview of comprehensive understanding of the exploitation of the extraordinary systemic and characteristics, as well as the fabrication processes and uses of g-C₃N₄.

A Pd^II-catalyzed tertiary C−H activation of cyclobutylmethyl ketones using a transient directing group is reported. An electron-deficient 2-pyridone ligand was identified as an external ligand to enable tertiary C−H activation. A variety of cyclobutylmethyl ketones bearing quaternary carbon centers was readily accessed in up to 81 % yield and >95 : 5 regioisomeric ratios of tertiary C−H arylation to β-methylene (β-methyl) or γ-C−H arylation.

Abstract

We report the first example of selective Pd^II-catalyzed tertiary C−H activation of cyclobutylmethyl ketones using a transient directing group. An electron-deficient 2-pyridone ligand was identified as the optimal external ligand to enable tertiary C−H activation. A variety of cyclobutylmethyl ketones bearing quaternary carbon centers was readily accessed without preinstalling internal directing groups in up to 81 % yield and >95 : 5 regioisomeric ratios of tertiary C−H arylation to β-methylene (β-methyl) or γ-C−H arylation.

Publication date: 10 February 2022

Source: Chem, Volume 8, Issue 2

Author(s): Hong Deng, Minyan Wang, Yong Liang, Xiangyang Chen, Tianhang Wang, Jonathan J. Wong, Yue Zhao, Kendall N. Houk, Zhuangzhi Shi