Tailored cobalt-salen complexes enable electrocatalytic intramolecular allylic C–H functionalizations

AbstractOxidative allylic C–H functionalization is a powerful tool to streamline organic synthesis as it minimizes the need for functional group activation and generates alkenyl-substituted products amenable to further chemical modifications. The intramolecular variants can be used to construct functionalized ring structures but remain limited in scope and by their frequent requirement for noble metal catalysts and stoichiometric chemical oxidants. Here we report an oxidant-free, electrocatalytic approach to achieve intramolecular oxidative allylic C–H amination and alkylation by employing tailored cobalt-salen complexes as catalysts. These reactions proceed through a radical mechanism and display broad tolerance of functional groups and alkene substitution patterns, allowing efficient coupling of di-, tri- and even tetrasubstituted alkenes with N- and C-nucleophiles to furnish high-value heterocyclic and carbocyclic structures.

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Dual-functional cobalt catalyst enables electrocatalytic allylic C–H alkylation

10.33774/chemrxiv-2021-tsk2m-v2 ◽

2021 ◽

Author(s):

Ming Chen ◽

Zheng-Jian Wu ◽

Jinshuai Song ◽

Hai-Chao Xu

Keyword(s):

Value Added ◽

Synthetic Methods ◽

Radical Mechanism ◽

Alkylation Reaction ◽

Coupling Reactions ◽

Carbon Nucleophiles ◽

Noble Metal Catalysts ◽

Cross Coupling Reactions ◽

Dual Functional ◽

Chemical Oxidants

Transition metal-catalyzed allylic substitution reactions of pre-activated allylation agents with nucleophiles are extensively studied synthetic methods that have enjoyed widespread applications in organic synthesis. The direct alkylation of allylic C–H bonds with nucleophiles, which minimizes pre-functionalization and converts inexpensive, abundantly available materials to value-added alkenyl-substituted products, remains challenging. Current methods generally involve C–H activation, require the use of noble-metal catalysts and stoichiometric chemical oxidants, and often show limited scope. Here we report an electrocatalytic allylic C–H alkylation reaction with carbon nucleophiles employing an easily available cobalt-salen complex as the molecular catalyst. These C(sp3)–H/C(sp3)–H cross-coupling reactions proceed through H2 evolution and require no external chemical oxidants. Importantly, the mild conditions and radical mechanism ensure excellent functional group tolerance and substrate compatibility with both linear and branched terminal alkenes. The synthetic utility of the electrochemical method is highlighted by its scalability (up to 200 mmol scale) and its successful application in the late-stage functionalization of complex structures.

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Asymmetric Ring-Opening of Epoxides Catalyzed by Metal–Salen Complexes

Catalysts ◽

10.3390/catal10060705 ◽

2020 ◽

Vol 10 (6) ◽

pp. 705

Author(s):

Anna Lidskog ◽

Yutang Li ◽

Kenneth Wärnmark

Keyword(s):

Functional Groups ◽

Organic Synthesis ◽

Ring Opening ◽

Kinetic Resolution ◽

Catalytic Systems ◽

Salen Complexes ◽

Epoxide Opening ◽

Ring Opening Of Epoxides ◽

One Step ◽

Asymmetric Ring Opening

The asymmetric ring-opening of epoxides is an important reaction in organic synthesis, since it allows for the enantioselective installation of two vicinal functional groups with specific stereochemistry within one step from a highly available starting material. An effective class of catalysts for the asymmetric ring-opening of epoxides is metal–salen complexes. This review summarizes the development of metal–salen catalyzed enantioselective desymmetrization of meso-epoxides and kinetic resolution of epoxides with various nucleophiles, including the design and application of both homogeneous- and heterogeneous epoxide-opening catalysts as well as multi-metallic covalent and supramolecular catalytic systems.

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A Brief Discussion on Nucleophilic Substitution Reaction on Saturated Carbon Atom

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.312.433 ◽

2013 ◽

Vol 312 ◽

pp. 433-437 ◽

Cited By ~ 1

Author(s):

Yan Ding

Keyword(s):

Reaction Mechanism ◽

Carbon Atom ◽

Nucleophilic Substitution ◽

Functional Groups ◽

Organic Synthesis ◽

Substitution Reaction ◽

Functional Group ◽

Hydrolysis Reaction ◽

Nucleophilic Substitution Reaction ◽

Saturated Carbon Atom

Nucleophilic substitution reaction is an important reaction of haloalkane. By such a reaction, halogen functional group can turn into various other functional groups. Therefore, it is widely used in organic synthesis and there are many researches on its reaction mechanism. Hydrolysis reaction of bromoalkane is especially a nucleophilic substitution reaction that is studied quite fully. This paper mainly discusses the nucleophilic substitution reaction on saturated carbon atom.

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Dioxasilepanyl Group as a Versatile Organometallic Unit: Studies in Stability, Reactivity, and Utility

Chemical Science ◽

10.1039/d1sc02083h ◽

2021 ◽

Author(s):

Hayate Saito ◽

Jun Shimokawa ◽

Hideki Yorimitsu

Keyword(s):

Functional Groups ◽

Organic Synthesis ◽

Functional Group ◽

Reaction Conditions ◽

Multistep Synthesis

Organic synthesis is orchestrated based on precise choices of functional groups and reactions employed. In a multistep synthesis, an ideal functional group should be orthogonal to various reaction conditions and...

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Styrene-divinylbenzene polymer oxidation catalyst

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19812657 ◽

1981 ◽

Vol 46 (11) ◽

pp. 2657-2662

Author(s):

Zdeněk Prokop ◽

Karel Setínek

Keyword(s):

Functional Groups ◽

Noble Metal ◽

Additional Data ◽

Catalytic Properties ◽

Metal Catalysts ◽

Oxidation Catalyst ◽

Noble Metal Catalysts ◽

Polymer Catalyst ◽

Styrene Divinylbenzene ◽

Polymer Oxidation

Some additional data about properties and applicability of a styrene-divinylbenzene polymer catalyst containing acidic and redox functional groups are reported. It is shown that the catalysts of this type can be prepared reproducibly and exhibit catalytic properties comparable to the properties of noble metal catalysts.

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Modern Organic Synthesis in the Laboratory

10.1093/oso/9780195187984.001.0001 ◽

2008 ◽

Cited By ~ 1

Author(s):

Jie Jack Li ◽

Chris Limberakis ◽

Derek A. Pflum

Keyword(s):

Organic Chemistry ◽

Graduate Students ◽

Organic Synthesis ◽

Functional Group ◽

Bond Formation ◽

Reaction Conditions ◽

Carbon Bond ◽

Oxidation Reduction ◽

Carbon Carbon Bond ◽

Daunting Task

Searching for reaction in organic synthesis has been made much easier in the current age of computer databases. However, the dilemma now is which procedure one selects among the ocean of choices. Especially for novices in the laboratory, it becomes a daunting task to decide what reaction conditions to experiment with first in order to have the best chance of success. This collection intends to serve as an "older and wiser lab-mate" one could have by compiling many of the most commonly used experimental procedures in organic synthesis. With chapters that cover such topics as functional group manipulations, oxidation, reduction, and carbon-carbon bond formation, Modern Organic Synthesis in the Laboratory will be useful for both graduate students and professors in organic chemistry and medicinal chemists in the pharmaceutical and agrochemical industries.

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Ligand-Driven Advances in Iridium Catalyzed sp3 C-H Borylation: 2,2’-Dipyridylarylmethane

Synlett ◽

10.1055/a-1344-1904 ◽

2020 ◽

Author(s):

Margaret R Jones ◽

Nathan D. Schley

Keyword(s):

Recent Work ◽

Organic Synthesis ◽

Functional Group ◽

Reaction Conditions ◽

Recent Advances ◽

Additional Ligand ◽

Limited Application ◽

Hydrocarbon Substrates ◽

Phenanthroline Ligands

The field of catalytic C-H borylation has grown considerably since its founding, providing a means for the preparation of synthetically versatile organoborane products. While sp2 C-H borylation methods have found widespread and practical use in organic synthesis, the analogous sp3 C-H borylation reaction remains challenging and has seen limited application. Existing catalysts are often hindered by incomplete consumption of the diboron reagent, poor functional group tolerance, harsh reaction conditions, and the need for excess or neat substrate. These challenges acutely affect C-H borylation chemistry of unactivated hydrocarbon substrates, which has lagged in comparison to methods for the C-H borylation of activated compounds. Herein we discuss recent advances in sp3 C-H borylation of undirected substrates in the context of two particular challenges: (1) utilization of the diboron reagent and (2) the need for excess or neat substrate. Our recent work on the application of dipyridylarylmethane ligands in sp3 C-H borylation has allowed us to make contributions in this space and has presented an additional ligand scaffold to supplement traditional phenanthroline ligands.

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Cycloaddition of Thiourea- and Guanidine-Substituted Furans to Dienophiles: A Comparison of the Environmentally-Friendly Methods

Chemistry Proceedings ◽

10.3390/ecsoc-24-08380 ◽

2020 ◽

Vol 3 (1) ◽

pp. 57

Author(s):

Luka Barešić ◽

Davor Margetić ◽

Zoran Glasovac

Keyword(s):

High Pressure ◽

Functional Groups ◽

Organic Synthesis ◽

High Speed ◽

Environmentally Friendly ◽

Microwave Assisted ◽

Pressure Synthesis ◽

Ultrasound Assisted ◽

Substituted Furans ◽

Guanidine Moiety

The cycloaddition strategy was employed in order to obtain a 7-oxanorbornene framework substituted with a guanidine moiety or its precursor functional groups: protected amine or thiourea. In order to optimize the conditions for the cycloaddition, several environmentally-friendly methods—microwave assisted organic synthesis, high pressure synthesis, high speed vibrational milling, and ultrasound assisted synthesis—were employed. The outcomes of the cycloaddition reactions were interpreted in terms of endo/exo selectivity, the conversion of the reactants to the product, and the isolated yields. In general, our results indicated the HP and HSVM approaches as the methods of choice to give good yields and conversions.

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Resilience of Epiphytic Lichens to Combined Effects of Increasing Nitrogen and Solar Radiation

Journal of Fungi ◽

10.3390/jof7050333 ◽

2021 ◽

Vol 7 (5) ◽

pp. 333

Author(s):

Lourdes Morillas ◽

Javier Roales ◽

Cristina Cruz ◽

Silvana Munzi

Keyword(s):

Global Change ◽

Solar Radiation ◽

Functional Groups ◽

Physiological Response ◽

Functional Group ◽

Environmental Drivers ◽

Combined Effects ◽

Environmental Stressor ◽

Comprehensive Understanding ◽

Direct Sunlight

Lichens are classified into different functional groups depending on their ecological and physiological response to a given environmental stressor. However, knowledge on lichen response to the synergistic effect of multiple environmental factors is extremely scarce, although vital to get a comprehensive understanding of the effects of global change. We exposed six lichen species belonging to different functional groups to the combined effects of two nitrogen (N) doses and direct sunlight involving both high temperatures and ultraviolet (UV) radiation for 58 days. Irrespective of their functional group, all species showed a homogenous response to N with cumulative, detrimental effects and an inability to recover following sunlight, UV exposure. Moreover, solar radiation made a tolerant species more prone to N pollution’s effects. Our results draw attention to the combined effects of global change and other environmental drivers on canopy defoliation and tree death, with consequences for the protection of ecosystems.

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