scholarly journals Rh(III)-Catalyzed Coupling of N-Chloroimines with α-Diazo-α-Phosphonoacetates for Skeleton-Oriented Synthesis of 2H-Isoindoles

2019 ◽  
Author(s):  
Bing Qi ◽  
Lei Li ◽  
Qi Wang ◽  
Wenjing Zhang ◽  
Lili Fang ◽  
...  
Keyword(s):  
Electrophilic Substitution ◽  
Chemical Space ◽  
Full Potential ◽  
Mechanistic Studies ◽  
Complete Elimination ◽  
Nucleophilic Reaction ◽  
Functionalization Reaction

A major hurdle for realizing the full potential of transition metalcatalyzed, directed C-H functionalization synthesis of heterocycles is the blockingof ability for designated structural elaboration by the reactivity-assisting groupderived, unintended appendages. We communicate herein Rh(III)-catalyzed coupling of N-chloroimines with α-diazo-α-phosphonoacetates for skeletonoriented synthesis (SOS) of 2H-Isoindoles. Comprehensive mechanistic studies with rhodacycle intermediates support an associative covalent relay mechanism for this first reported N-chloroimine-directed C-H functionalization reaction. Theinitial dechlorination/dephosphonation under Rh(III) catalysis and subsequent deesterification under Ni(II) catalysis allow the complete elimination of unintended appendages and full exposure of reactivity for C3 and N2 ring atoms. The proofof - concept utility has been demonstrated with electrophilic substitution at the C3 site (formylation, azo derivatization) and nucleophilic reaction (methylation) at the N2 site, showcasing the enormous synthetic potential of SOS for attaching structurally unrelated appendages and enabling entry to distinct chemical space.

scholarly journals Rh(III)-Catalyzed Coupling of N-Chloroimines with α-Diazo-α-Phosphonoacetates for Skeleton-Oriented Synthesis of 2H-Isoindoles

2019 ◽  
Author(s):  
Bing Qi ◽  
Lei Li ◽  
Qi Wang ◽  
Wenjing Zhang ◽  
Lili Fang ◽  
...  
Keyword(s):  
Electrophilic Substitution ◽  
Chemical Space ◽  
Full Potential ◽  
Mechanistic Studies ◽  
Complete Elimination ◽  
Nucleophilic Reaction ◽  
Functionalization Reaction

A major hurdle for realizing the full potential of transition metalcatalyzed, directed C-H functionalization synthesis of heterocycles is the blockingof ability for designated structural elaboration by the reactivity-assisting groupderived, unintended appendages. We communicate herein Rh(III)-catalyzed coupling of N-chloroimines with α-diazo-α-phosphonoacetates for skeletonoriented synthesis (SOS) of 2H-Isoindoles. Comprehensive mechanistic studies with rhodacycle intermediates support an associative covalent relay mechanism for this first reported N-chloroimine-directed C-H functionalization reaction. Theinitial dechlorination/dephosphonation under Rh(III) catalysis and subsequent deesterification under Ni(II) catalysis allow the complete elimination of unintended appendages and full exposure of reactivity for C3 and N2 ring atoms. The proofof - concept utility has been demonstrated with electrophilic substitution at the C3 site (formylation, azo derivatization) and nucleophilic reaction (methylation) at the N2 site, showcasing the enormous synthetic potential of SOS for attaching structurally unrelated appendages and enabling entry to distinct chemical space.

scholarly journals Rh(III)-Catalyzed Coupling of N-Chloroimines with α-Diazo-α-Phosphonoacetates for Skeleton-Oriented Synthesis of 2H-Isoindoles

2019 ◽  
Author(s):  
Bing Qi ◽  
Lei Li ◽  
Qi Wang ◽  
Wenjing Zhang ◽  
Jin Zhu
Keyword(s):  
Electrophilic Substitution ◽  
Chemical Space ◽  
Full Potential ◽  
Mechanistic Studies ◽  
Complete Elimination ◽  
Nucleophilic Reaction ◽  
Functionalization Reaction

A major hurdle for realizing the full potential of transition metalcatalyzed, directed C-H functionalization synthesis of heterocycles is the blockingof ability for designated structural elaboration by the reactivity-assisting groupderived, unintended appendages. We communicate herein Rh(III)-catalyzed coupling of N-chloroimines with α-diazo-α-phosphonoacetates for skeletonoriented synthesis (SOS) of 2H-Isoindoles. Comprehensive mechanistic studies with rhodacycle intermediates support an associative covalent relay mechanism for this first reported N-chloroimine-directed C-H functionalization reaction. Theinitial dechlorination/dephosphonation under Rh(III) catalysis and subsequent deesterification under Ni(II) catalysis allow the complete elimination of unintended appendages and full exposure of reactivity for C3 and N2 ring atoms. The proofof - concept utility has been demonstrated with electrophilic substitution at the C3 site (formylation, azo derivatization) and nucleophilic reaction (methylation) at the N2 site, showcasing the enormous synthetic potential of SOS for attaching structurally unrelated appendages and enabling entry to distinct chemical space.

scholarly journals C-H Functionalization Reactions of Unprotected N-Heterocycles by Gold Catalyzed Carbene Transfer

2020 ◽  
Author(s):  
Sripati Jana ◽  
Claire Empel ◽  
Chao Pei ◽  
Polina Aseeva ◽  
Thanh Vinh Nguyen ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Functional Groups ◽  
Gold Catalyst ◽  
Protecting Groups ◽  
Transfer Reactions ◽  
Mechanistic Studies ◽  
Economic Strategies ◽  
Carbene Transfer ◽  
Functionalization Reaction

<p>The C-H functionalization reaction of N-heterocycles with unprotected N-H group is one of the most step-economic strategies to introduce functional groups without the need of installation and removal of protecting groups. Despite recent significant advances in C-H functionalization chemistry, this strategy remains unsatisfactorily developed. In this report, we disclose a simple and straightforward protocol to allow for the selective C-H functionalization of unprotected double benzannellated N-heterocycles via gold catalyzed carbene transfer reactions (29 examples, up to 86% yield). The scope of the reaction can also be expanded to the corresponding protected heterocycles (37 examples, up to 98% yield), further demonstrating the generality of this method. Mechanistic studies by DFT calculations underpin the importance of the gold catalyst and reveal that the selectivity of this reaction is driven by trace amounts of water present in the reaction mixture.</p>

scholarly journals Micellar photocatalysis enables divergent C-H arylation and N dealkylation of benzamides via N-acyliminium cations

2022 ◽  
Author(s):  
Martyna Cybularczyk-Cecotka ◽  
Jędrzej Predygier ◽  
Stefano Crespi ◽  
Joanna Szczepanik ◽  
Maciej Giedyk
Keyword(s):  
Methylene Blue ◽  
Light Source ◽  
Catalytic System ◽  
Chemical Space ◽  
Mechanistic Studies ◽  
Mild Conditions ◽  
Reducing Conditions ◽  
Benzamide Derivatives

Micellar photocatalysis has recently opened new avenues to activate strong carbon halide bonds. So far, however, it has mainly explored strongly reducing conditions restricting the available chemical space to radical or anionic reactivity. Here, we demonstrate a radical-polar crossover process involving cationic intermediates, which enables chemodivergent modification of chlorinated benzamide derivatives via either C H arylation or N dealkylation. The catalytic system operates under mild conditions employing methylene blue as a photocatalyst and blue LEDs as the light source. Factors determining the reactivity of substrates and preliminary mechanistic studies are presented.

scholarly journals Utilization of Cellulose to Its Full Potential: A Review on Cellulose Dissolution, Regeneration, and Applications

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4344
Author(s):  
Sanjit Acharya ◽  
Sumedha Liyanage ◽  
Prakash Parajuli ◽  
Shaida Sultana Rumi ◽  
Julia L. Shamshina ◽  
...  
Keyword(s):  
Hydrophobic Interactions ◽  
Structural Characteristics ◽  
Synthetic Polymers ◽  
Chemical Processing ◽  
Full Potential ◽  
Cellulose Dissolution ◽  
Natural Polymer ◽  
Mechanistic Studies ◽  
Solvent Systems ◽  
Subsequent Regeneration

As the most abundant natural polymer, cellulose is a prime candidate for the preparation of both sustainable and economically viable polymeric products hitherto predominantly produced from oil-based synthetic polymers. However, the utilization of cellulose to its full potential is constrained by its recalcitrance to chemical processing. Both fundamental and applied aspects of cellulose dissolution remain active areas of research and include mechanistic studies on solvent–cellulose interactions, the development of novel solvents and/or solvent systems, the optimization of dissolution conditions, and the preparation of various cellulose-based materials. In this review, we build on existing knowledge on cellulose dissolution, including the structural characteristics of the polymer that are important for dissolution (molecular weight, crystallinity, and effect of hydrophobic interactions), and evaluate widely used non-derivatizing solvents (sodium hydroxide (NaOH)-based systems, N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl), N-methylmorpholine-N-oxide (NMMO), and ionic liquids). We also cover the subsequent regeneration of cellulose solutions from these solvents into various architectures (fibers, films, membranes, beads, aerogels, and hydrogels) and review uses of these materials in specific applications, such as biomedical, sorption, and energy uses.

scholarly journals Mechanistic studies of non-canonical amino acid mutagenesis

2021 ◽  
Author(s):  
Rachel C. Fleisher ◽  
Nina Michael ◽  
Ruben L Gonzalez
Keyword(s):  
Protein Synthesis ◽  
Single Molecule ◽  
Cellular Protein ◽  
Full Potential ◽  
Mechanistic Studies ◽  
The Past ◽  
The Poor ◽  
Protein Synthesis Machinery ◽  
Canonical Amino Acid ◽  
Amino Acid Mutagenesis

Over the past decade, harnessing the cellular protein synthesis machinery to incorporate non-canonical amino acids (ncAAs) into tailor-made peptides has significantly advanced many aspects of molecular science. More recently, groundbreaking progress in our ability to engineer this machinery for improved ncAA incorporation has led to significant enhancements of this powerful tool for biology and chemistry. By revealing the molecular basis for the poor or improved incorporation of ncAAs, mechanistic studies of ncAA incorporation by the protein synthesis machinery have tremendous potential for informing and directing such engineering efforts. In this chapter, we describe a set of complementary biochemical and single-molecule fluorescence assays that we have adapted for mechanistic studies of ncAA incorporation. Collectively, these assays provide data that can guide engineering of the protein synthesis machinery to expand the range of ncAAs that can be incorporated into peptides and increase the efficiency with which they can be incorporated, thereby enabling the full potential of ncAA mutagenesis technology to be realized.

scholarly journals Electrophilic Substitution of Thiophenes with Arylpalladium(II) and Platinum(II) Complexes: Mechanistic Studies on Palladium-Catalyzed CH Arylation of Thiophenes

2009 ◽  
Vol 82 (5) ◽  
pp. 555-562 ◽  
Author(s):  
Atsushi Sugie ◽  
Hirotoshi Furukawa ◽  
Yuji Suzaki ◽  
Kohtaro Osakada ◽  
Munetaka Akita ◽  
...  
Keyword(s):  
Electrophilic Substitution ◽  
Mechanistic Studies ◽  
Palladium Catalyzed

scholarly journals C-H Functionalization Reactions of Unprotected N-Heterocycles by Gold Catalyzed Carbene Transfer

2020 ◽  
Author(s):  
Sripati Jana ◽  
Claire Empel ◽  
Chao Pei ◽  
Polina Aseeva ◽  
Thanh Vinh Nguyen ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Functional Groups ◽  
Gold Catalyst ◽  
Protecting Groups ◽  
Transfer Reactions ◽  
Mechanistic Studies ◽  
Economic Strategies ◽  
Carbene Transfer ◽  
Functionalization Reaction

<p>The C-H functionalization reaction of N-heterocycles with unprotected N-H group is one of the most step-economic strategies to introduce functional groups without the need of installation and removal of protecting groups. Despite recent significant advances in C-H functionalization chemistry, this strategy remains unsatisfactorily developed. In this report, we disclose a simple and straightforward protocol to allow for the selective C-H functionalization of unprotected double benzannellated N-heterocycles via gold catalyzed carbene transfer reactions (29 examples, up to 86% yield). The scope of the reaction can also be expanded to the corresponding protected heterocycles (37 examples, up to 98% yield), further demonstrating the generality of this method. Mechanistic studies by DFT calculations underpin the importance of the gold catalyst and reveal that the selectivity of this reaction is driven by trace amounts of water present in the reaction mixture.</p>

Mechanistic Studies on the Nucleophilic Reaction of Porphyrins with Organolithium Reagents

2001 ◽  
Vol 66 (26) ◽  
pp. 8693-8700 ◽  
Author(s):  
Xiangdong Feng ◽  
Ines Bischoff ◽  
Mathias O. Senge
Keyword(s):  
Mechanistic Studies ◽  
Nucleophilic Reaction ◽  
Organolithium Reagents

scholarly journals Direct deoxygenative borylation of carboxylic acids

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jianbin Li ◽  
Chia-Yu Huang ◽  
Mohamad Ataya ◽  
Rustam Z. Khaliullin ◽  
Chao-Jun Li
Keyword(s):  
Carboxylic Acids ◽  
Boronic Acid ◽  
Chemical Space ◽  
Boronic Acids ◽  
Mechanistic Studies ◽  
Sodium Salts ◽  
Aromatic Carboxylic Acids ◽  
Metal Free ◽  
Aliphatic Carboxylic Acids ◽  
Shelf Stable

AbstractCarboxylic acids are readily available, structurally diverse and shelf-stable; therefore, converting them to the isoelectronic boronic acids, which play pivotal roles in different settings, would be highly enabling. In contrast to the well-recognised decarboxylative borylation, the chemical space of carboxylic-to-boronic acid transformation via deoxygenation remains underexplored due to the thermodynamic and kinetic inertness of carboxylic C-O bonds. Herein, we report a deoxygenative borylation reaction of free carboxylic acids or their sodium salts to synthesise alkylboronates under metal-free conditions. Promoted by a uniquely Lewis acidic and strongly reducing diboron reagent, bis(catecholato)diboron (B2cat2), a library of aromatic carboxylic acids are converted to the benzylboronates. By leveraging the same borylative manifold, a facile triboration process with aliphatic carboxylic acids is also realised, diversifying the pool of available 1,1,2-alkyl(trisboronates) that were otherwise difficult to access. Detailed mechanistic studies reveal a stepwise C-O cleavage profile, which could inspire and encourage future endeavours on more appealing reductive functionalisation of oxygenated feedstocks.

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