Recent approaches for C–C bond formation via direct dehydrative coupling strategies

Kumar, Rakesh; Eycken, Erik V. Van der

doi:10.1039/c2cs35397k

Cited by 265 publications

(97 citation statements)

References 127 publications

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“…As alcohols and aromatic hydrocarbons are among the most abundant and commonly used feedstocks in industrial processes, their exploitation in C-C coupling reactions has become one of the significant approaches in direct functionalization of C-H bonds, avoiding the need for halogen-containing intermediates and thereby eliminating synthetic steps, which results in enhanced atom economy [3]. Alcohols are a highly attractive class of alkylating agents since they are inexpensive, they are usually easily derived from natural sources and the only side product resulting from associated coupling reaction is water [4]. On the other hand, the flexibility of the alkene functional group offers leverage for subsequent transformation into various other moieties [5].…”

Section: Introductionmentioning

confidence: 99%

Molecular iodine as a mild catalyst for cross-coupling of alkenes and alcohols

Čebular

Stavber

2018

Pure and Applied Chemistry

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C-C bond formation is one of the most fundamental approaches toward molecular diversity in organic synthesis. In pursuit of environmentally friendlier chemical approaches to organic chemistry, we present a new metal-free method for direct dehydrative cross-coupling of alcohols and alkenes using molecular iodine as a Lewis acid catalyst under solvent-free reaction conditions. The reaction is atom-economical, tolerant to air and allows simple synthetic procedure, furnishing C sp 3 -C sp 2 coupling products with yields up to 97 %. The method has proved efficient for coupling of secondary benzyl alcohols with phenyl-substituted alkenes.

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Section: Introductionmentioning

confidence: 99%

Molecular iodine as a mild catalyst for cross-coupling of alkenes and alcohols

Čebular

Stavber

2018

Pure and Applied Chemistry

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“…[6,7] Beyond that, the development of protocols to replace toxic alkyl halides with more benign alkylating agents is crucial to chemical technology and environmental concerns, [8,9] and it will also continue to influence and motivate the development of catalysts for environmental remediation. [10] One area in this field that has attracted much attention is the reaction of indoles to give their derivatives [11,12] such as bis(indolyl)methanes, which are more attractive active materials as bioactive metabolites of terrestrial and marine origin [13,14] and have wide medicinal applications in the pharmaceutical and agrochemical industries. [11,15] Ethyl ammonium nitrate (EAN) was the first ionic liquid (IL) [16] discovered with acidic properties (pH 5), [17] which has been used in various organic reactions.…”

Section: Introductionmentioning

confidence: 99%

Friedel–Crafts Alkylation of Indoles Exclusively in Water Catalyzed by Ionic Liquid Supported on a Polyacrylonitrile Fiber: A Simple “Release and Catch” Catalyst

Lin

Zhang

2014

ChemCatChem

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A series of ionic liquids supported on polyacrylonitrile fibers (FSILs) served as “release and catch” catalysts to mediate the Friedel–Crafts alkylation of indoles exclusively in water. Detailed characterization by elemental analysis, FTIR spectroscopy, and SEM confirmed that a significant amount of ionic liquid was immobilized on the surface layer of the fiber, and excellent results, in terms of the simple procedure, high yields (87–96 %), and superior catalytic recyclability (over 10 cycles), are reported for the metal and cosolvent‐free synthesis of a wide variety of bis(indolyl)methanes at room temperature. The reason why the reaction catalyzed with FSILs only proceeded in water is explained, and a “release and catch” catalytic mechanism is proposed. Moreover, the procedures can be scaled up efficiently, and the solvent can be recovered and reused without contamination. The prominent features of the fiber catalyst are very attractive for fixed‐bed reactors in the chemical industry.

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“…1 The ability to form multiple C-C bonds using iterative or one-pot methods allows a rapid increase in molecular complexity.…”

Section: Introductionmentioning

confidence: 99%

“…1 The ability to form multiple C-C bonds using iterative or one-pot methods allows a rapid increase in molecular complexity. [2][3][4][5] While many such sequences are known, there is still room to exploit new reactivity patterns and different chemical combinations derived from reactive intermediates.…”

Section: Introductionmentioning

confidence: 99%

Iterative reactions of transient boronic acids enable sequential C–C bond formation

et al. 2016

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(2016). Iterative reactions of transient boronic acids enable sequential C-C bond formation. Nature Chemistry, 8 (4), 360-363. Copyright and re-use policySee http://shura.shu.ac.uk/information.html Sheffield Hallam University Research Archivehttp://shura.shu.ac.uk The ability to form multiple carbon-carbon bonds in a controlled sequence and thus rapidly build molecular complexity in an iterative fashion is an important goal in modern chemical synthesis. In recent times, transition metal-catalysed coupling reactions have dominated in the development of C-C bond forming processes. A desire to reduce the reliance on precious metals and a need to obtain products with very low levels of metal impurities has brought a renewed focus on metal-free coupling processes. Here, we report the in situ preparation of reactive allylic and benzylic boronic acids, obtained by reacting flow-generated diazo compounds with boronic acids, and their application in controlled iterative C-C bond forming reactions is described. Thus far we have shown the formation of up to three C-C bonds in a sequence including the final trapping of a reactive boronic acid species with an aldehyde to generate a range of new chemical structures. Iterative reactions of transient boronic acids enable sequential C-C bond formation IntroductionThe generation of C-C bonds is at the heart of synthetic organic chemistry. 1 The ability to form multiple C-C bonds using iterative or one-pot methods allows a rapid increase in molecular complexity.2-5 While many such sequences are known, there is still room to exploit new reactivity patterns and different chemical combinations derived from reactive intermediates. 6 In recent times, transition metal chemistry has dominated C-C bond cross-coupling strategies. [7][8][9][10][11][12][13] This powerful approach has been central to the planning and execution of modern synthesis programs both in academia and industry. Nevertheless, the desire of industry to reduce its reliance on the use of precious metals in coupling reactions and the need for very low metal levels in active pharmaceutical ingredients has increased interest in metal-free coupling processes considerably. 14 Boronic esters 15 and acids 16 are considered to be important coupling partners as they are versatile intermediates for the preparation of a wide variety of molecules. For example, Barluenga 17 and others [18][19][20] recently demonstrated the powerful application of a reductive metal-free cross-coupling between tosylhydrazones and boronic acids. The reaction likely proceeds via a carbene-like species which on combination with a boronic acid initiates a sequence of reactions that terminates in the formation of a coupling product. However, high temperatures are necessary to affect these coupling processes so that any further exploitation of potentially useful intermediates in the reaction has not been possible so far.From our own mechanistic studies based on the use of flow-generated diazo compounds, 21 in the metal-free cross-coupling with aryl boronic a...

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Recent approaches for C–C bond formation via direct dehydrative coupling strategies

Cited by 265 publications

References 127 publications

Molecular iodine as a mild catalyst for cross-coupling of alkenes and alcohols

Molecular iodine as a mild catalyst for cross-coupling of alkenes and alcohols

Friedel–Crafts Alkylation of Indoles Exclusively in Water Catalyzed by Ionic Liquid Supported on a Polyacrylonitrile Fiber: A Simple “Release and Catch” Catalyst

Iterative reactions of transient boronic acids enable sequential C–C bond formation

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