scholarly journals Recent Advances in C–H Bond Functionalization with Ruthenium-Based Catalysts

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 173 ◽  
Author(s):  
Keisham Singh
Keyword(s):  
Transition Metals ◽  
Bond Cleavage ◽  
Rapid Development ◽  
Bond Functionalization ◽  
Bond Forming ◽  
The Past ◽  
Tremendous Progress ◽  
Specific Manner ◽  
Ruthenium Catalysis ◽  
Cleavage Reactions

The past decades have witnessed rapid development in organic synthesis via catalysis, particularly the reactions through C–H bond functionalization. Transition metals such as Pd, Rh and Ru constitute a crucial catalyst in these C–H bond functionalization reactions. This process is highly attractive not only because it saves reaction time and reduces waste,but also, more importantly, it allows the reaction to be performed in a highly region specific manner. Indeed, several organic compounds could be readily accessed via C–H bond functionalization with transition metals. In the recent past, tremendous progress has been made on C–H bond functionalization via ruthenium catalysis, including less expensive but more stable ruthenium(II) catalysts. The ruthenium-catalysed C–H bond functionalization, viz. arylation, alkenylation, annulation, oxygenation, and halogenation involving C–C, C–O, C–N, and C–X bond forming reactions, has been described and presented in numerous reviews. This review discusses the recent development of C–H bond functionalization with various ruthenium-based catalysts. The first section of the review presents arylation reactions covering arylation directed by N–Heteroaryl groups, oxidative arylation, dehydrative arylation and arylation involving decarboxylative and sp3-C–H bond functionalization. Subsequently, the ruthenium-catalysed alkenylation, alkylation, allylation including oxidative alkenylation and meta-selective C–H bond alkylation has been presented. Finally, the oxidative annulation of various arenes with alkynes involving C–H/O–H or C–H/N–H bond cleavage reactions has been discussed.

Distal radical migration strategy: an emerging synthetic means

2018 ◽  
Vol 47 (3) ◽  
pp. 654-667 ◽  
Author(s):  
Weipeng Li ◽  
Wentao Xu ◽  
Jin Xie ◽  
Shouyun Yu ◽  
Chengjian Zhu
Keyword(s):  
Rapid Development ◽  
Long Distance ◽  
Migration Strategy ◽  
Bond Functionalization ◽  
The Past ◽  
Radical Migration

In the past three years, we have witnessed the rapid development of C–C and C–H bond functionalization by means of long-distance radical migration events which bring us a new platform to deal with the challenging C–C and C–H bond functionalization.

scholarly journals Transamidation of Amides and Amidation of Esters by Selective N–C(O)/O–C(O) Cleavage Mediated by Air- and Moisture-Stable Half-Sandwich Nickel(II)–NHC Complexes

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 188
Author(s):  
Jonathan Buchspies ◽  
Md. Mahbubur Rahman ◽  
Michal Szostak
Keyword(s):  
Organic Synthesis ◽  
Bond Cleavage ◽  
Methyl Esters ◽  
Heterocyclic Carbenes ◽  
Amide Bond ◽  
Amide Bonds ◽  
Bond Forming ◽  
Cleavage Reactions ◽  
Metal Catalyzed ◽  
Half Sandwich

The formation of amide bonds represents one of the most fundamental processes in organic synthesis. Transition-metal-catalyzed activation of acyclic twisted amides has emerged as an increasingly powerful platform in synthesis. Herein, we report the transamidation of N-activated twisted amides by selective N–C(O) cleavage mediated by air- and moisture-stable half-sandwich Ni(II)–NHC (NHC = N-heterocyclic carbenes) complexes. We demonstrate that the readily available cyclopentadienyl complex, [CpNi(IPr)Cl] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), promotes highly selective transamidation of the N–C(O) bond in twisted N-Boc amides with non-nucleophilic anilines. The reaction provides access to secondary anilides via the non-conventional amide bond-forming pathway. Furthermore, the amidation of activated phenolic and unactivated methyl esters mediated by [CpNi(IPr)Cl] is reported. This study sets the stage for the broad utilization of well-defined, air- and moisture-stable Ni(II)–NHC complexes in catalytic amide bond-forming protocols by unconventional C(acyl)–N and C(acyl)–O bond cleavage reactions.

Connecting Remote C–H Bond Functionalization and Decarboxylative Coupling Using Simple Amines

2019 ◽  
Author(s):  
Francisco de Azambuja ◽  
Ming-Hsiu Yang ◽  
Alexander Bruecker ◽  
Paul Cheong ◽  
Ryan Altman
Keyword(s):  
Organic Molecules ◽  
Mechanistic Studies ◽  
Bond Functionalization ◽  
Bond Forming ◽  
Decarboxylative Coupling

The manuscript describes a Pd-catalyzed reaction of benzylic electrophiles that gives para-substituted arene products. Mechanistic studies suggest a mechanism involving a dearomative C–C bond-forming step, followed by base-mediated rearomatization. This mechanism is uncommon and underappreciated in Pd-catalysis and further exploitation of this mechanism should enable access to other organic molecules.

Stability and Folding of the Unusually Stable Hemoglobin from Synechocystis is Subtly Optimized and Dependent on the Key Heme Pocket Residues.

2020 ◽  
Vol 27 ◽  
Author(s):  
Sheetal Uppal ◽  
Mohd. Asim Khan ◽  
Suman Kundu
Keyword(s):  
Molten Globule ◽  
Life Forms ◽  
Model System ◽  
Heme Pocket ◽  
The Past ◽  
Specific Manner ◽  
Delivery Vehicles ◽  
The Stability ◽  
Key Residues ◽  
Synechocystis Sp

Aims: The aim of our study is to understand the biophysical traits that govern the stability and folding of Synechocystis hemoglobin, a unique cyanobacterial globin that displays unusual traits not observed in any of the other globins discovered so far. Background: For the past few decades, classical hemoglobins such as vertebrate hemoglobin and myoglobin have been extensively studied to unravel the stability and folding mechanisms of hemoglobins. However, the expanding wealth of hemoglobins identified in all life forms with novel properties, like heme coordination chemistry and globin fold, have added complexity and challenges to the understanding of hemoglobin stability, which has not been adequately addressed. Here, we explored the unique truncated and hexacoordinate hemoglobin from the freshwater cyanobacterium Synechocystis sp. PCC 6803 known as “Synechocystis hemoglobin (SynHb)”. The “three histidines” linkages to heme are novel to this cyanobacterial hemoglobin. Objective: Mutational studies were employed to decipher the residues within the heme pocket that dictate the stability and folding of SynHb. Methods: Site-directed mutants of SynHb were generated and analyzed using a repertoire of spectroscopic and calorimetric tools. Result: The results revealed that the heme was stably associated to the protein under all denaturing conditions with His117 playing the anchoring role. The studies also highlighted the possibility of existence of a “molten globule” like intermediate at acidic pH in this exceptionally thermostable globin. His117 and other key residues in the heme pocket play an indispensable role in imparting significant polypeptide stability. Conclusion: Synechocystis hemoglobin presents an important model system for investigations of protein folding and stability in general. The heme pocket residues influenced the folding and stability of SynHb in a very subtle and specific manner and may have been optimized to make this Hb the most stable known as of date. Other: The knowledge gained hereby about the influence of heme pocket amino acid side chains on stability and expression is currently being utilized to improve the stability of recombinant human Hbs for efficient use as oxygen delivery vehicles.

The Medicinal Chemistry of Therapeutic Peptides: Recent Developments in Synthesis and Design Optimizations

2019 ◽  
Vol 26 (13) ◽  
pp. 2330-2355 ◽  
Author(s):  
Anutthaman Parthasarathy ◽  
Sasikala K. Anandamma ◽  
Karunakaran A. Kalesh
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Therapeutic Potential ◽  
The Past ◽  
Recombinant Production ◽  
Tremendous Progress ◽  
Recent Developments ◽  
Therapeutic Peptides ◽  
Development Processes ◽  
Delivery Strategies

Peptide therapeutics has made tremendous progress in the past decade. Many of the inherent weaknesses of peptides which hampered their development as therapeutics are now more or less effectively tackled with recent scientific and technological advancements in integrated drug discovery settings. These include recent developments in synthetic organic chemistry, high-throughput recombinant production strategies, highresolution analytical methods, high-throughput screening options, ingenious drug delivery strategies and novel formulation preparations. Here, we will briefly describe the key methodologies and strategies used in the therapeutic peptide development processes with selected examples of the most recent developments in the field. The aim of this review is to highlight the viable options a medicinal chemist may consider in order to improve a specific pharmacological property of interest in a peptide lead entity and thereby rationally assess the therapeutic potential this class of molecules possesses while they are traditionally (and incorrectly) considered ‘undruggable’.

Hydrogenation-dehydrogenation and cleavage functions of hydrorefining catalysts studied by the reaction of tetrahydrothiophene

1986 ◽  
Vol 51 (12) ◽  
pp. 2770-2780 ◽  
Author(s):  
Alexandra Drahorádová ◽  
Miroslav Zdražil
Keyword(s):  
Activated Carbon ◽  
Catalyst Surface ◽  
Bond Cleavage ◽  
Unsaturated Hydrocarbons ◽  
Cleavage Reactions

The reaction of tetrahydrothiophene in a stream of nitrogen was used to study the relations between dehydrogenation and C-S cleavage reactions on sulphided Co-Mo/Al2O3 catalysts. The course of the reaction was compared for Co-Mo catalysts supported on alumina and activated carbon, for alumina alone as well as for a Pt/C catalyst. The effect of substitution of nitrogen for hydrogen, of the addition of water to the feed, of pre-sulphidation of catalysts and their deactivation by coking on the rate and selectivity of the reaction were also investigated. The results showed that hydrogenation-dehydrogenation and dehydrosulphurization activity of the sulphide catalysts have the same origin. Hydrogen accelerates dehydrosulphurization on the sulphide catalysts by removing sulphur and unsaturated hydrocarbons formed on catalyst surface by C-S bond cleavage reactions.

History—an overview

2018 ◽  
Author(s):  
Oriol Bohigas ◽  
Hans A. Weidenmüller
Keyword(s):  
Random Matrix Theory ◽  
Random Matrix ◽  
Matrix Theory ◽  
Rapid Development ◽  
The Past ◽  
History Of ◽  
And Mathematics

An overview of the history of random matrix theory (RMT) is provided in this chapter. Starting from its inception, the authors sketch the history of RMT until about 1990, focusing their attention on the first four decades of RMT. Later developments are partially covered. In the past 20 years RMT has experienced rapid development and has expanded into a number of areas of physics and mathematics.

Organophotoredox-Catalyzed C–H Alkylation of Imidazoheterocycles with Malonates: Total Synthesis of Zolpidem

Synthesis ◽  
2020 ◽  
Author(s):  
Narendra R. Chaubey ◽  
Anant R. Kapdi ◽  
Biswanath Maity
Keyword(s):  
Total Synthesis ◽  
Room Temperature ◽  
Drug Molecule ◽  
Bond Functionalization ◽  
First Report ◽  
Mild Conditions ◽  
The Past ◽  
Hypnotic Drug ◽  
Free Environment

AbstractOrganophotocatalytic C–H bond functionalization has attracted a lot of attention in the past several years due to the possibility of catalyzing reactions in a metal- and peroxide-free environment. Continuing on these lines, an organophotoredox-catalyzed C–H functionalization of imidazo[1,2-a]pyridines and related heterocycles with bromomalonates under mild conditions is reported, providing excellent yields of the products at room temperature. This is the first report involving malonates as coupling partners leading to the synthesis of a range of functionalized products including total synthesis of zolpidem, a sedative­-hypnotic drug molecule.

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

Molecules ◽  
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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