Supported Metal Catalysts for the Synthesis of N-Heterocycles

Nitrogen-containing heterocycles are important scaffolds for a large number of compounds with biological, pharmaceutical, industrial and optoelectronic applications. A wide range of different methodologies for the preparation of N-heterocycles are based on metal-catalyzed cyclization of suitable substrates. Due to the growing interest in Green Chemistry criteria over the past two decades, the use of supported metal catalysts in the preparation of N-heterocycles has become a central topic in Organic Chemistry. Here we will give a critical overview of all the solid supported metal catalysts applied in the synthesis of N-heterocycles, following a systematic approach as a function of the type of support: (i) metal catalysts supported on inorganic matrices; (ii) metal catalysts supported on organic matrices; (iii) metal catalysts supported on hybrid inorganic-organic matrices. In particular, we will try to emphasize the effective heterogeneity and recyclability of the described metal catalysts, specifying which studies were carried out in order to evaluate these aspects.

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Recent advance in NHC-palladium catalysis for alkynes chemistry: versatile synthesis and applications

Organic Chemistry Frontiers ◽

10.1039/d1qo00111f ◽

2021 ◽

Author(s):

Jianxiao Li ◽

Dan He ◽

Zidong Lin ◽

Wanqing Wu ◽

Huanfeng Jiang

Keyword(s):

Transition Metal ◽

Palladium Catalysis ◽

Metal Catalysts ◽

Chemical Transformations ◽

The Past ◽

Transition Metal Catalyzed ◽

Metal Catalyzed

During the past decades, alkynes chemistry has attracted considerable attention owing to their unique and idiographic nucleophilic and electrophilic properties in transition-metal-catalyzed chemical transformations. Among the various metal catalysts, palladium...

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High-Resolution Scanning Electron Microscopy and Microanalysis of Supported Metal Catalysts

MRS Proceedings ◽

10.1557/proc-589-259 ◽

1999 ◽

Vol 589 ◽

Cited By ~ 1

Author(s):

Jingyue Liu

Keyword(s):

High Resolution ◽

Low Voltage ◽

Supported Catalysts ◽

Metal Catalysts ◽

Supported Metal Catalysts ◽

Surface Sensitivity ◽

Brightness Field ◽

Backscattered Electron ◽

Enhanced Surface ◽

Supported Metal

AbstractThe use of a high-brightness field emission gun and novel secondary electron detection systems makes it possible to acquire nanometer-resolution surface images of bulk materials, even at low electron beam voltages. The advantages of low-voltage SEM include enhanced surface sensitivity, reduced sample charging on non-conducting materials, and significantly reduced electron range and interaction volume. High-resolution images formed by collecting the backscattered electron signal can give information about the size and spatial distribution of metal nanoparticles in supported catalysts. Low-voltage XEDS can provide compositional information of bulk samples with enhanced surface sensitivity and significantly improved spatial resolution. High-resolution SEM techniques enhance our ability to detect and, subsequently, analyze the composition of nanoparticles in supported metal catalysts. Applications of high-resolution SEM imaging and microanalysis techniques to the study of industrial supported catalysts are discussed.

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Modern Synthetic Methods for the Stereoselective Construction of 1,3-Dienes

Molecules ◽

10.3390/molecules26020249 ◽

2021 ◽

Vol 26 (2) ◽

pp. 249

Author(s):

Raquel G. Soengas ◽

Humberto Rodríguez-Solla

Keyword(s):

Organic Chemistry ◽

Natural Products ◽

Functional Group ◽

Biological Activities ◽

Synthetic Methods ◽

Bond Forming ◽

Drug Candidates ◽

The Past ◽

Wide Range

The 1,3-butadiene motif is widely found in many natural products and drug candidates with relevant biological activities. Moreover, dienes are important targets for synthetic chemists, due to their ability to give access to a wide range of functional group transformations, including a broad range of C-C bond-forming processes. Therefore, the stereoselective preparation of dienes have attracted much attention over the past decades, and the search for new synthetic protocols continues unabated. The aim of this review is to give an overview of the diverse methodologies that have emerged in the last decade, with a focus on the synthetic processes that meet the requirements of efficiency and sustainability of modern organic chemistry.

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C-H bond functionalization using Pd and Au supported catalysts with mechanistic insights of the active species

Synthesis ◽

10.1055/a-1468-1455 ◽

2021 ◽

Author(s):

Tamao Ishida ◽

Zhenzhong Zhang ◽

Haruno Murayama ◽

Eiji Yamamoto ◽

Makoto Tokunaga

Keyword(s):

Aromatic Compounds ◽

Reaction Mechanisms ◽

Bond Activation ◽

Supported Catalysts ◽

Metal Catalysts ◽

Active Species ◽

Supported Metal Catalysts ◽

Bond Functionalization ◽

Bond Forming ◽

Supported Metal

The C–H functionalization has been extensively studied as a direct C–C bond forming reaction with high atomic efficiency. The efforts have also been made on the reaction using supported catalysts, which are superior in terms of catalyst separation from the reaction mixture and reusability. In this review, an overview of the C–H functionalization reactions, especially for Pd and Au supported catalysts will be described. In particular, we discuss reaction mechanisms, active species, leaching, reusability, etc. 1 Introduction 2 Types of supported metal catalysts and their active species 3 Modes of C–H bond activation 4 Oxidative C–H C–H coupling of aryl compounds 5 C–H C–H coupling where one side is aromatic 6 C–H acylation of aromatic compounds and related reactions 7 Conclusion

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