Friedel-Crafts-Type Reactions with Electrochemically Generated Electrophiles from Donor-Acceptor Cyclopropanes and -Butanes.
TL;DR: In this article, a general electrochemical method to functionalize donor-acceptor (D-A) cyclopropanes and -butanes with arenes utilizing Friedel-Crafts-type reactivity was described.
About: This article is published in Organic Letters.The article was published on 2021-07-07. It has received 16 citations till now. The article focuses on the topics: Electrophile & Friedel–Crafts reaction.
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TL;DR: In this article , a novel electrochemical ring-opening dicarboxylation of C−C single bonds in strained rings with CO2 has been investigated, which is the first realization of an electroreductive ring opening reaction of strained rings, including commercialized ones.
Abstract: Diacids are important monomers in the polymer industry to construct valuable materials. Dicarboxylation of unsaturated bonds, such as alkenes and alkynes, with CO2 has been demonstrated as a promising synthetic method. However, dicarboxylation of C─C single bonds with CO2 has rarely been investigated. Herein we report a novel electrochemical ring-opening dicarboxylation of C─C single bonds in strained rings with CO2. Structurally diverse glutaric acid and adipic acid derivatives were synthesized from substituted cyclopropanes and cyclobutanes in moderate to high yields. In contrast to oxidative ring openings, this is also the first realization of an electroreductive ring-opening reaction of strained rings, including commercialized ones. Control experiments suggested that radical anions and carbanions might be the key intermediates in this reaction. Moreover, this process features high step and atom economy, mild reaction conditions (1 atm, room temperature), good chemoselectivity and functional group tolerance, low electrolyte concentration, and easy derivatization of the products. Furthermore, we conducted polymerization of the corresponding diesters with diols to obtain a potential UV-shielding material with a self-healing function and a fluorine-containing polyester, whose performance tests showed promising applications.
41 citations
TL;DR: In this paper , a photoredox-driven ring-opening C( sp 3 )-heteroatom bond formation of arylcyclopropanes is presented, which enables the construction of structurally diversified while sterically congested dialkyl ether, alkyl ester, alcohol, amine, chloride/fluoride, azide and also thiocyanate derivatives.
Abstract: Abstract Sterically congested C–O and C–N bonds are ubiquitous in natural products, pharmaceuticals, and bioactive compounds. However, the development of a general method for the efficient construction of those sterically demanding covalent bonds still remains a formidable challenge. Herein, a photoredox-driven ring-opening C( sp 3 )–heteroatom bond formation of arylcyclopropanes is presented, which enables the construction of structurally diversified while sterically congested dialkyl ether, alkyl ester, alcohol, amine, chloride/fluoride, azide and also thiocyanate derivatives. The selective single electron oxidation of aryl motif associated with the thermodynamic driving force from ring strain-release is the key for this transformation. By this synergistic activation mode, C–C bond cleavage of otherwise inert cyclopropane framework is successfully unlocked. Further mechanistic and computational studies disclose a complete stereoinversion upon nucleophilic attack, thus proving a concerted S N 2-type ring-opening functionalization manifold, while the regioselectivity is subjected to an orbital control scenario.
9 citations
TL;DR: In this article , a class of highly activated donor-acceptor cyclopropanes bearing only a single, vinylogous acceptor is presented, which readily undergo cycloadditions with aldehydes, ketones, thioketones, nitriles, naphth-2-ols and various other substrates to yield the corresponding carbo-and heterocycles.
Abstract: Abstract A novel class of highly activated donor‐acceptor cyclopropanes bearing only a single, vinylogous acceptor is presented. These strained moieties readily undergo cycloadditions with aldehydes, ketones, thioketones, nitriles, naphth‐2‐ols and various other substrates to yield the corresponding carbo‐ and heterocycles. Diastereocontrol can be achieved through the choice of catalyst (Brønsted or Lewis acid). The formation of tetrahydrofurans was shown to be highly enantiospecific when chiral cyclopropanes are employed. A series of mechanistic and kinetic experiments was conducted to elucidate a plausible catalytic cycle and to rationalize the stereochemical outcome.
7 citations
TL;DR: In this article , a Lu(OTf)3-catalyzed formal [4+4] cycloaddition reaction of cyclobutane 1,1-diesters with anthranils was reported to deliver oxa-bridged eight-membered heterocycles.
3 citations
References
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TL;DR: This review discusses advances in synthetic organic electrochemistry since 2000 with enabling methods and synthetic applications analyzed alongside innate advantages as well as future challenges of electroorganic chemistry.
Abstract: Electrochemistry represents one of the most intimate ways of interacting with molecules. This review discusses advances in synthetic organic electrochemistry since 2000. Enabling methods and synthetic applications are analyzed alongside innate advantages as well as future challenges of electroorganic chemistry.
1,930 citations
TL;DR: This Review surveys recent developments in electrochemical synthesis that will influence the future of this area and examines the role of stoichiometric reagents in this area.
Abstract: The direct synthetic organic use of electricity is currently experiencing a renaissance. More synthetically oriented laboratories working in this area are exploiting both novel and more traditional concepts, paving the way to broader applications of this niche technology. As only electrons serve as reagents, the generation of reagent waste is efficiently avoided. Moreover, stoichiometric reagents can be regenerated and allow a transformation to be conducted in an electrocatalytic fashion. However, the application of electroorganic transformations is more than minimizing the waste footprint, it rather gives rise to inherently safe processes, reduces the number of steps of many syntheses, allows for milder reaction conditions, provides alternative means to access desired structural entities, and creates intellectual property (IP) space. When the electricity originates from renewable resources, this surplus might be directly employed as a terminal oxidizing or reducing agent, providing an ultra-sustainable and therefore highly attractive technique. This Review surveys recent developments in electrochemical synthesis that will influence the future of this area.
825 citations
TL;DR: This Review highlights the appropriate tools for successfully employing donor-acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
Abstract: The effective use of ring strain has been applied to considerable advantage for the construction of complex systems. The focus here is directed towards cyclopropanes as building blocks for organic synthesis. Although thermodynamics should take the side of synthetic chemists, only a specific substitution pattern at the cyclopropane ring allows for particularly mild, efficient, and selective transformations. The required decrease in the activation barrier is achieved by the combined effects of vicinal electron-donating and electron-accepting moieties. This Review highlights the appropriate tools for successfully employing donor–acceptor cyclopropanes in ring-opening reactions, cycloadditions, and rearrangements.
805 citations
TL;DR: This tutorial review focuses on the latter, describing recent developments and applications of cyclopropane ring-expansion reactions in natural product synthesis and several newly developed methods providing access to densely functionalized heterocycles.
Abstract: The construction of heterocyclic compounds from activated cyclopropane derivatives offers an alternative strategy for the preparation of molecules that may be of interest from a structural or biological standpoint. Several newly developed methods provide access to densely functionalized heterocycles in a manner that can be considered useful for both diversity- and target-oriented synthetic approaches. This tutorial review focuses on the latter, describing recent developments and applications of cyclopropane ring-expansion reactions in natural product synthesis.
693 citations
TL;DR: The ring-strain theory was formulated by Adolf von Baeyer over one hundred years ago as discussed by the authors, and it has repeatedly stimulated experimental and theoretical chemists to investigate the structure, energy and reactivity of organic compounds.
Abstract: “Die Ringschliesung ist offenbar diejenige Erscheinung, welche am meisten uber die raumliche Anordnung der Atome Auskunft geben kann. Wenn eine Kette von 5 und 6 Gliedern sich leicht, eine von weniger oder mehr Gliedern sich schwierig oder auch gar nicht schliesen last, so mussen dafur offenbar raumliche Grunde vorhanden sein.… Die vier Valenzen des Kohlenstoffatoms wirken in den Richtungen, welche den Mittelpunkt der Kugel mit den Tetraederecken verbinden, und welche miteinander einen Winkel von 109°28′ machen. Die Richtung der Anziehung kann eine Ablenkung erfahren, die jedoch eine mit der Grose der Letzteren wachsende Spannung zur Folge hat,”[ ] This is the quintessence of the “ring-strain theory” formulated by Adolf von Baeyer over one hundred years ago. Although it is today only one facet of the many aspects of strain theory, it has repeatedly stimulated experimental and theoretical chemists. Among the most spectacular of the recent successes in synthetic chemistry are the syntheses of tetra-tert-butyltetrahedrane and [1.1.1]propellane. The reasons for the great stability of these two highly strained compounds are completely different. The experimental findings as well as the results of theoretical analysis by means of molecular mechanics and ab initio calculations have contributed decisively to our present state of knowledge of the structure, energy, and reactivity of organic compounds.
494 citations