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Amino- and Alkoxybenziodoxoles: Facile Preparation and Use as Arynophiles. Chemistry 2024; 30:e202400894. [PMID: 38494436 DOI: 10.1002/chem.202400894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 03/15/2024] [Accepted: 03/15/2024] [Indexed: 03/19/2024]
Abstract
We report here on the facile synthesis of amino- and alkoxy-λ3-iodanes supported by a benziodoxole (BX) template and their use as arynophiles. The amino- and alkoxy-BX derivatives can be readily synthesized by reacting the respective amines or alcohols with chlorobenziodoxole in the presence of a suitable base. Unlike previously known nitrogen- and oxygen-bound iodane compounds, which have primarily been employed as electrophilic group transfer agents or oxidants, the present amino- and alkoxy-BX reagents manifest themselves as nucleophilic amino and alkoxy transfer agents toward arynes. This reactivity leads to the aryne insertion into the N-I(III) or O-I(III) bond to afford ortho-amino- and ortho-alkoxy-arylbenziodoxoles, iodane compounds nontrivial to procure by existing methods. The BX group in these insertion products exhibits excellent leaving group ability, enabling diverse downstream transformations.
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2
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Three-component N-alkenylation of azoles with alkynes and iodine(III) electrophile: synthesis of multisubstituted N-vinylazoles. Beilstein J Org Chem 2024; 20:891-897. [PMID: 38711595 PMCID: PMC11070964 DOI: 10.3762/bjoc.20.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 04/11/2024] [Indexed: 05/08/2024] Open
Abstract
A stereoselective N-alkenylation of azoles with alkynes and iodine(III) electrophile is reported. The reaction between various azoles and internal alkynes is mediated by benziodoxole triflate as the electrophile in a trans-fashion, affording azole-bearing vinylbenziodoxoles in moderate to good yields. The tolerable azole nuclei include pyrazole, indazole, 1,2,3-triazole, benzotriazole, and tetrazole. The iodanyl group in the product can be leveraged as a versatile synthetic handle, allowing for the preparation of hitherto inaccessible types of densely functionalized N-vinylazoles.
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3
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Carboiodanation of Arynes: Organoiodine(III) Compounds as Nucleophilic Organometalloids. J Am Chem Soc 2024; 146:3910-3919. [PMID: 38315817 DOI: 10.1021/jacs.3c11524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Organic iodine(III) compounds represent the most widely used hypervalent halogen compounds in organic synthesis, where they typically perform the role of an electrophile or oxidant to functionalize electron-rich or -nucleophilic organic compounds. In contrast to this convention, we discovered their unique reactivity as organometallic-like nucleophiles toward arynes. Equipped with diverse transferable ligands and supported by a tethered spectator ligand, the organoiodine(III) compounds undergo addition across the electrophilic C-C triple bond of arynes while retaining the trivalency of the iodine center. This carboiodanation reaction can forge a variety of aryl-alkynyl, aryl-alkenyl, and aryl-(hetero)aryl bonds along with the concurrent formation of an aryl-iodine(III) bond under mild conditions. The newly formed aryl-iodine(III) bond serves as a versatile linchpin for downstream transformations, particularly as an electrophilic reaction site. The amphoteric nature of the iodine(III) group as a metalloid and a leaving group in this sequence enables the flexible and expedient synthesis of extended π-conjugated molecules and privileged biarylphosphine ligands, where all of the iodine(III)-containing compounds can be handled as air- and thermally stable materials.
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Stereoselective Approach to Multisubstituted Enolates from Unactivated Alkynes: Oxyalkylidenation of Alkynyl Ketone Enolates with Aldehydes. J Org Chem 2023; 88:14096-14104. [PMID: 37733580 DOI: 10.1021/acs.joc.3c01615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/23/2023]
Abstract
The preparation of multisubstituted enolates with precise regio- and stereocontrol is a nontrivial task when conventional deprotonation methods are used on the corresponding carbonyl compounds. We describe herein an approach to preparing stereodefined enolates by leveraging the stereoselective oxyfunctionalization of unactivated alkynes, particularly in the context of the alkynylogous aldol reaction. trans-Iodo(III)acetoxylation of alkynes and subsequent Sonogashira coupling allow for the facile preparation of multisubstituted enynyl acetates, which can be deacetylated by MeLi into the corresponding enolates. The alkynyl enolates react with aldehydes to afford γ,δ-unsaturated β-diketones through a cascade of alkynylogous aldol addition, intramolecular Michael addition, and ring opening of the oxetene intermediate.
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5
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Site‐Selective C–H Alkenylation of N‐Heteroarenes by Ligand‐Directed Co/Al and Co/Mg Cooperative Catalysis. Angew Chem Int Ed Engl 2023. [DOI: 10.1002/ange.202301006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
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6
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Site-Selective C-H Alkenylation of N-Heteroarenes by Ligand-Directed Co/Al and Co/Mg Cooperative Catalysis. Angew Chem Int Ed Engl 2023; 62:e202301006. [PMID: 36855924 DOI: 10.1002/anie.202301006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/18/2023] [Accepted: 02/27/2023] [Indexed: 03/02/2023]
Abstract
We report herein the design and development of Co/Al and Co/Mg bimetallic catalysts, supported by a phosphine/secondary phosphine oxide (PSPO) bifunctional ligand, for the site-selective C-H alkenylation of nitrogen-containing heteroarenes with alkynes. These catalysts enable the alkenylation of pyridine, pyridone, and imidazo[1,2-a]pyridine derivatives at the C-H site proximal to the Lewis basic nitrogen or oxygen atom, which represents a selectivity profile distinct from that of the previously developed cobalt-diphosphine/aluminum catalyst. The alkenylated products were obtained in moderate to good yields using various heterocycles and differently substituted internal alkynes. Kinetic isotope effect experiments suggest the irreversibility of the C-H activation step, the relevance of which to the rate-limiting step depends on the reaction conditions. Density functional theory calculations indicate that ligand-to-ligand hydrogen transfer is the common mechanism of C-H activation.
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7
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Exploring New Reactions and Syntheses of Trivalent Iodine Compounds. J SYN ORG CHEM JPN 2022. [DOI: 10.5059/yukigoseikyokaishi.80.1011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Stereoselective Synthesis of β-Alkoxy-β-amido Vinylbenziodoxoles via Iodo(III)etherification of Ynamides. Org Lett 2022; 24:6914-6918. [PMID: 36125122 DOI: 10.1021/acs.orglett.2c02570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A trans-iodo(III)etherification reaction of ynamides with benziodoxole triflate and alcohols is reported. Despite the sensitivity of ynamides and enamides toward Brønsted acid, the reaction could be successfully performed under carefully controlled conditions to afford β-alkoxy-β-amido vinylbenziodoxoles in moderate to good yields. The products could be subjected to a sequence of cross-coupling via C-I(III) bond cleavage and electrophilic halogenation of the resulting α-alkoxyenamides, allowing for the preparation of densely functionalized esters.
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9
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Diastereoselective Conversion of Cyclopropanols to Cyclopentane-1,3-diols via Aldol Dimerization of Zinc Homoenolates. CHEM LETT 2022. [DOI: 10.1246/cl.220311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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11
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Zinc-Mediated Hydroxyallylation of Aldehydes with Cyclopropanols: Direct Access to Vicinal anti- sec, tert-Diols via Enolized Homoenolates. Org Lett 2022; 24:960-965. [PMID: 35030003 DOI: 10.1021/acs.orglett.1c04331] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Direct and diastereoselective synthesis of vicinal anti-sec,tert-diols has been achieved by zinc-mediated α-hydroxyallylation of aldehydes with cyclopropanols. The reaction features the action of the zinc-enolized homoenolate as a γ-oxyallyl nucleophile toward the carbonyl electrophile. The diastereoselectivity of the present reaction is ascribed to the strong preference for a chelated (Z)-configuration of the enolized homoenolate as well as the bicyclic chairlike transition state it forms with the aldehyde, where the aldehyde substituent prefers to occupy the pseudoaxial position.
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12
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Regio- and Stereoselective Synthesis of Enol Carboxylate, Phosphate, and Sulfonate Esters via Iodo(III)functionalization of Alkynes. Org Lett 2021; 24:430-434. [PMID: 34962817 DOI: 10.1021/acs.orglett.1c04123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
β-Iodo(III)enol carboxylates, phosphates, and tosylates can be efficiently synthesized through regio- and stereoselective iodo(III)functionalization of alkynes. The combination of chlorobenziodoxole and silver salt has proven to generate a versatile cationic iodine(III) electrophile to activate alkynes and engage various carboxylic acids, triethyl phosphate, and p-toluenesulfonic acid as nucleophiles. The β-iodo(III)enol esters serve as starting materials for the synthesis of multisubstituted alkenes through sequential cross-coupling of the C-I(III) and C-O bonds.
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Ritter-type iodo(iii)amidation of unactivated alkynes for the stereoselective synthesis of multisubstituted enamides. Chem Sci 2021; 12:15128-15133. [PMID: 34909154 PMCID: PMC8612402 DOI: 10.1039/d1sc05240c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 10/26/2021] [Indexed: 01/24/2023] Open
Abstract
The Ritter reaction, Brønsted- or Lewis acid-mediated amidation of alkene or alcohol with nitrile via a carbocation, represents a classical method for the synthesis of tertiary amides. Although analogous reactions through a vinyl cation or a species alike may offer a route to enamide, an important synthetic building block as well as a common functionality in bioactive compounds, such transformations remain largely elusive. Herein, we report a Ritter-type trans-difunctionalization of alkynes with a trivalent iodine electrophile and nitrile, which affords β-iodanyl enamides in moderate to good yields. Mediated by benziodoxole triflate (BXT), the reaction proves applicable to a variety of internal alkynes as well as to various alkyl- and arylnitriles. The benziodoxole group in the product serves as a versatile handle for further transformations, thus allowing for the preparation of various tri- and tetrasubstituted enamides that are not readily accessible by other means.
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Zinc-Catalyzed β-Functionalization of Cyclopropanols via Enolized Homoenolate. J Am Chem Soc 2021; 143:18400-18405. [PMID: 34714060 DOI: 10.1021/jacs.1c10109] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We report herein a zinc-catalyzed β-allylation of cyclopropanols with Morita-Baylis-Hillman (MBH) carbonates with retention of the cyclopropane ring. The reaction is promoted by a zinc aminoalkoxide catalyst, affording cyclopropyl-fused α-alkylidene-δ-valerolactone derivatives in moderate to good yields. Mechanistic experiments suggest that the present reaction does not proceed via direct β-C-H cleavage of the cyclopropanol, but involves zinc homoenolate and its enolization to generate a key bis-nucleophilic species. α-Allylation of this "enolized homoenolate" with MBH carbonate would be followed by regeneration of the cyclopropane ring and irreversible lactonization. The enolized homoenolate mechanism has also been proven to allow for β-functionalization with alkylidenemalononitrile as the reaction partner. A sequence of the present reaction and known cyclopropanol transformation provides an opportunity to transform a simple cyclopropanol into α,β- or β,β-difunctionalized ketones.
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15
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Because I Wanted to be Independent. J SYN ORG CHEM JPN 2021. [DOI: 10.5059/yukigoseikyokaishi.79.971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Iron-Catalyzed Remote C–H Alkylation of 8-Amidoquinolines with Cycloalkanes. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/a-1337-5416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AbstractAn iron-catalyzed, peroxide-mediated cross-dehydrogenative coupling between 8-amidoquinolines and cycloalkanes has been developed for the site-selective alkylation of the quinoline nucleus at the C5 position. The reaction tolerates various substituted N-(quinolin-8-yl)benzamides and N-(quinolin-8-yl)alkylamides, affording the corresponding C5-alkylation products in good yields. On the basis of control experiments, a reaction mechanism involving the addition of an alkyl radical to an iron-chelated intermediate is proposed.
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Abstract
We report herein a nickel-catalyzed ring-opening allylation of cyclopropanols with allylic carbonates that occurs under mild and neutral conditions. The reaction displays linear selectivity for both linear and branched acyclic allylic carbonates and is also applicable to cyclic allylic carbonates, affording a variety of δ,ε-unsaturated ketones in moderate to good yields. Mechanistic experiments are in accord with a catalytic cycle involving decarboxylative oxidative addition of allylic carbonate to Ni(0), alkoxide exchange with cyclopropanol, cyclopropoxide-to-homoenolate conversion on Ni(II), and C-C reductive elimination.
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Robust Cobalt Catalyst for Nitrile/Alkyne [2+2+2] Cycloaddition: Synthesis of Polyarylpyridines and Their Mechanochemical Cyclodehydrogenation to Nitrogen-Containing Polyaromatics*. Angew Chem Int Ed Engl 2021; 60:9627-9634. [PMID: 33559370 DOI: 10.1002/anie.202017220] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Indexed: 12/16/2022]
Abstract
The transition-metal-catalyzed [2+2+2] cycloaddition of nitriles and alkynes is an established synthetic approach to pyridines; however, these cycloadditions often rely on the use of tethered diynes or cyanoalkynes as one of the reactants. Thus, examples of efficient, fully intermolecular catalytic [2+2+2] pyridine synthesis, especially those employing unactivated nitriles and internal alkynes leading to pentasubstituted pyridines, remain scarce. Herein, we report on simple and inexpensive catalytic systems based on cobalt(II) iodide, 1,3-bis(diphenylphosphino)propane, and Zn that promote [2+2+2] cycloaddition of various nitriles and diarylacetylenes for the synthesis of a broad range of polyarylated pyridines. DFT studies support a reaction pathway involving oxidative coupling of two alkynes, insertion of the nitrile into a cobaltacyclopentadiene, and C-N reductive elimination. The resulting tetra- and pentaarylpyridines serve as precursors to hitherto unprecedented nitrogen-containing polycyclic aromatic hydrocarbons via mechanochemically assisted multifold reductive cyclodehydrogenation.
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Robust Cobalt Catalyst for Nitrile/Alkyne [2+2+2] Cycloaddition: Synthesis of Polyarylpyridines and Their Mechanochemical Cyclodehydrogenation to Nitrogen‐Containing Polyaromatics**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202017220] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Enantioselective Conjugate Addition of Catalytically Generated Zinc Homoenolate. J Am Chem Soc 2021; 143:4775-4781. [PMID: 33724809 DOI: 10.1021/jacs.1c00869] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We report herein an enantioselective conjugate addition reaction of a zinc homoenolate, catalytically generated via ring opening of a cyclopropanol, to an α,β-unsaturated ketone. The reaction is promoted by a zinc aminoalkoxide catalyst generated from Et2Zn and a chiral β-amino alcohol to afford 1,6-diketones, which undergo, upon heating, intramolecular aldol condensation to furnish highly substituted cyclopentene derivatives with good to high enantioselectivities. The reaction has proved applicable to various 1-substituted cyclopropanols as well as chalcones and related enones. The chiral amino alcohol has proved to enable ligand-accelerated catalysis of the homoenolate generation and its conjugate addition. Positive nonlinear effects and lower reactivity of a racemic catalyst have been observed, which can be attributed to a stable and inactive heterochiral zinc aminoalkoxide dimer.
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Iodo(III)-Meyer-Schuster Rearrangement of Propargylic Alcohols Promoted by Benziodoxole Triflate. Org Lett 2021; 23:1113-1117. [PMID: 33439023 DOI: 10.1021/acs.orglett.1c00039] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Benziodoxole triflate (BXT), a cyclic iodine(III) electrophile, has been found to promote a rearrangement of propargylic alcohols into α,β-unsaturated ketones bearing an α-λ3-iodanyl group. This iodo(III)-Meyer-Schuster rearrangement proceeds under mild conditions and tolerates a variety of functionalized propargylic alcohols, thus complementing previously reported halogen-intercepted Meyer-Schuster rearrangement. The α-λ3-iodanylenones can be utilized for facile Pd-catalyzed cross-coupling for the synthesis of multisubstituted enones.
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Metal-Catalyzed Transformations of Cyclopropanols via Homoenolates. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20200270] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Cobalt/Lewis Acid Catalysis for Hydrocarbofunctionalization of Alkynes via Cooperative C-H Activation. J Am Chem Soc 2020; 142:12878-12889. [PMID: 32573213 DOI: 10.1021/jacs.0c06412] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A catalytic system comprising a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines and related azines, imidazo[1,2-a]pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic systems for analogous transformations, the present catalytic systems not only feature convenient setup using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp) but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Meanwhile, the present catalytic system proved to promote exclusively C5-selective alkenylation of imidazo[1,2-a]pyridine derivatives. Mechanistic studies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkenyl(carbamoyl)cobalt intermediate.
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Fluorobenziodoxole−BF
3
Reagent for Iodo(III)etherification of Alkynes in Ethereal Solvent. Chem Asian J 2020; 15:2166-2169. [DOI: 10.1002/asia.202000653] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Indexed: 12/19/2022]
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Site-selective aromatic C-H λ 3-iodanation with a cyclic iodine(iii) electrophile in solution and solid phases. Chem Sci 2020; 11:7356-7361. [PMID: 34123017 PMCID: PMC8159425 DOI: 10.1039/d0sc02737e] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
An efficient and site-selective aromatic C-H λ3-iodanation reaction is achieved using benziodoxole triflate (BXT) as an electrophile under room temperature conditions. The reaction tolerates a variety of electron-rich arenes and heteroarenes to afford the corresponding arylbenziodoxoles in moderate to good yields. The reaction can also be performed mechanochemically by grinding a mixture of solid arenes and BXT under solvent-free conditions. The arylbenziodoxoles can be used for various C-C and C-heteroatom bond formations, and are also amenable to further modification by electrophilic halogenation. DFT calculations suggested that the present reaction proceeds via a concerted λ3-iodanation-deprotonation transition state, where the triflate anion acts as an internal base.
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Cobalt‐Catalyzed Intramolecular Hydroacylation Involving Cyclopropane Cleavage. Chemistry 2020; 26:8302-8307. [DOI: 10.1002/chem.202001223] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/09/2020] [Indexed: 11/06/2022]
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27
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Stereoselective Access to Highly Substituted Vinyl Ethers via trans-Difunctionalization of Alkynes with Alcohols and Iodine(III) Electrophile. J Am Chem Soc 2020; 142:8619-8624. [DOI: 10.1021/jacs.0c04140] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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28
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Synthesis of triphenylene-fused phosphole oxides via C-H functionalizations. Beilstein J Org Chem 2020; 16:524-529. [PMID: 32273913 PMCID: PMC7113549 DOI: 10.3762/bjoc.16.48] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 03/20/2020] [Indexed: 01/14/2023] Open
Abstract
The synthesis of triphenylene-fused phosphole oxides has been achieved through two distinct C–H functionalization reactions as key steps. The phosphole ring was constructed by a three-component coupling of 3-(methoxymethoxy)phenylzinc chloride, an alkyne, and dichlorophenylphosphine, involving the regioselective C–H activation of the C2 position of the arylzinc intermediate via 1,4-cobalt migration. The resulting 7-hydroxybenzo[b]phosphole derivative was used for further π-extension through Suzuki–Miyaura couplings and a Scholl reaction, the latter closing the triphenylene ring. The absorption and emission spectra of the thus-synthesized compounds illustrated their nature as hybrids of triphenylene and benzo[b]phosphole.
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Cobalt-Catalyzed, N–H Imine-Directed Arene C–H Benzylation with Benzyl Phosphates. J Org Chem 2019; 84:13172-13178. [DOI: 10.1021/acs.joc.9b01775] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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30
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Abstract
A cobalt-diphosphine catalyst has been found to promote a selective 1:2 coupling reaction between aldehydes and allenes to form β,δ-dialkylidene ketones, featuring skipped diene moieties, with high regioselectivities and stereoselectivities. The reaction is distinct from previously reported, rhodium-catalyzed aldehyde-allene 1:2 coupling to afford β,γ-dialkylidene ketones bearing 1,3-diene moieties. The present hydroacylative dimerization involves a unique allene/allene oxidative cyclization mode to form a C1-C2 linkage between the allene molecules.
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Pd-Catalyzed Annulation of 1-Halo-8-arylnaphthalenes and Alkynes Leading to Heptagon-Embedded Aromatic Systems. Chemistry 2019; 25:9395-9399. [PMID: 30457177 DOI: 10.1002/chem.201805746] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Indexed: 11/11/2022]
Abstract
A palladium-catalyzed heptagon-forming annulation reaction between 1-halo-8-arylnaphthalene and diarylacetylene is reported. The reaction is promoted using a catalytic system comprised of Pd(OAc)2 , moderately electron-deficient triarylphosphine P(4-ClC6 H4 )3 , and Ag2 CO3 to afford benzo[4,5]cyclohepta[1,2,3-de]naphthalene derivatives in moderate to good yields, in preference to fluoranthene as a competing byproduct. Twofold annulation can also be achieved to access a novel heptagon-embedded polycyclic aromatic hydrocarbon compound.
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Iron-Catalyzed ortho C-H Arylation and Methylation of Pivalophenone N-H Imines. CHEMSUSCHEM 2019; 12:3049-3053. [PMID: 30786170 DOI: 10.1002/cssc.201900164] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/19/2019] [Indexed: 06/09/2023]
Abstract
Iron-catalyzed ortho C-H arylation and methylation reactions of pivalophenone N-H imines are reported. The pivaloyl N-H imine proved an excellent directing group for the arylation with diarylzinc reagents in the presence of an iron-diphosphine catalyst and 2,3-dichlorobutane at room temperature. A similar catalytic system also allowed methylation with Me3 Al at 70 °C. The pivaloyl imine of the product could be readily converted to a cyano group, thus allowing convenient preparation of ortho-functionalized benzonitriles.
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Cobalt-Catalyzed Tandem Radical Cyclization/C–C Coupling Initiated by Directed C–H Activation. Org Lett 2019; 21:5238-5242. [DOI: 10.1021/acs.orglett.9b01846] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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34
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Cobalt-Catalyzed Enantioselective and Chemodivergent Addition of Cyclopropanols to Oxabicyclic Alkenes. ACS Catal 2019. [DOI: 10.1021/acscatal.9b00655] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Stereocontrolled Synthesis of Halovinylbenziodoxoles by Hydro- and Iodochlorination of Ethynylbenziodoxoles. Chemistry 2019; 25:7839-7842. [PMID: 31020740 DOI: 10.1002/chem.201901543] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 04/23/2019] [Indexed: 12/12/2022]
Abstract
We report herein the synthesis of highly substituted and stereochemically well-defined vinylbenziodoxole (VBX) derivatives through hydrochlorination and iodochlorination of ethynylbenziodoxoles. The hydrochlorination is achieved using pyridine hydrochloride as an HCl source in an anti-fashion under mild, open-air conditions to afford a 2-chlorinated VBX product, which serves as a useful building block for the stereoselective synthesis of trisubstituted alkenes. Meanwhile, iodochlorination with iodine monochloride proceeds in an unusual syn-pathway, stereoselectively affording a tetrasubstituted VBX derivative.
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Abstract
New phospha[5]helicene derivatives featuring angular fusion of phosphole and carbohelicene moieties have been synthesized using 7-hydroxybenzo[ b]phosphole oxide as a key intermediate, which can be regioselectively prepared through one-pot multicomponent coupling. The structural behavior of the present phospha[5]helicene oxide, sulfide, and gold complex in the solid and solution states, along with DFT calculations, demonstrated close correlation between the P-centered chirality and the helical chirality as well as facile helicity inversion and equilibrium between the diastereomers in solution.
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Photosensitized, Energy-Transfer-Mediated Cyclization of 2-(1-Arylvinyl)benzaldehydes to Anthracen-9-(10H)-ones. Org Lett 2019; 21:1202-1206. [DOI: 10.1021/acs.orglett.9b00182] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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38
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Cobalt-Catalyzed Regio- and Diastereoselective Formal [3 + 2] Cycloaddition between Cyclopropanols and Allenes. ACS Catal 2019. [DOI: 10.1021/acscatal.8b05114] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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39
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Cobalt-Catalyzed Intermolecular [2+2] Cycloaddition between Alkynes and Allenes. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201813283] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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40
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Cobalt-Catalyzed Intermolecular [2+2] Cycloaddition between Alkynes and Allenes. Angew Chem Int Ed Engl 2019; 58:2500-2504. [PMID: 30614605 DOI: 10.1002/anie.201813283] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 12/26/2018] [Indexed: 12/25/2022]
Abstract
An intermolecular [2+2] cycloaddition reaction between an alkyne and an allene is reported. In the presence of a cobalt(I)/diphosphine catalyst, a near equimolar mixture of the alkyne and allene is converted into a 3-alkylidenecyclobutene derivative in good yield with high regioselectivity. The reaction tolerates a variety of internal alkynes and mono- or disubstituted allenes bearing various functional groups. The reaction is proposed to involve regioselective oxidative cyclization of the alkyne and allene to form a 4-alkylidenecobaltacyclopentene intermediate, with subsequent C-C reductive elimination.
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Abstract
This Short Review describes recent developments in cobalt-catalyzed enantioselective C–C bond-forming reactions. The article focuses on reactions that most likely involve chiral organocobalt species as crucial catalytic intermediates and their mechanistic aspects.1 Introduction2 Hydrovinylation3 C–H Functionalization4 Cycloaddition and Cyclization5 Addition of Carbon Nucleophiles6 Cross-Coupling7 Conclusion
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Divergent ring-opening coupling between cyclopropanols and alkynes under cobalt catalysis. Chem Sci 2018; 9:6928-6934. [PMID: 30210767 PMCID: PMC6124909 DOI: 10.1039/c8sc02074d] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/13/2018] [Indexed: 12/04/2022] Open
Abstract
Cobalt catalysts promote ring-opening coupling between cyclopropanols and unactivated alkynes to give β-alkenyl ketones or cyclopentenols with exquisite chemoselectivity control.
Cobalt–diphosphine catalysts promote ring-opening coupling reactions between cyclopropanols and unactivated internal alkynes, affording either β-alkenyl ketones or multisubstituted cyclopentenol derivatives in good yields with good to excellent regioselectivities. The chemoselectivity between these β-alkenylation and [3 + 2] annulation reactions, which likely share a cobalt homoenolate as a key catalytic intermediate, is exquisitely controlled by the reaction conditions, with the solvent being a major controlling factor. The reactions are proposed to involve ring opening of cobalt cyclopropoxide into homoenolate, migratory insertion of the alkyne into the Co–C bond, and protodemetalation or intramolecular carbonyl addition of the resulting alkenylcobalt species. The feasibility of these reaction steps was supported by DFT calculations.
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Cobalt‐Catalyzed Intramolecular Reactions between a Vinylcyclopropane and an Alkyne: Switchable [5+2] Cycloaddition and Homo‐Ene Pathways. Angew Chem Int Ed Engl 2018; 57:6558-6562. [DOI: 10.1002/anie.201803162] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Indexed: 02/03/2023]
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45
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Cobalt‐Catalyzed Intramolecular Reactions between a Vinylcyclopropane and an Alkyne: Switchable [5+2] Cycloaddition and Homo‐Ene Pathways. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201803162] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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46
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Cobalt-catalyzed directed C-H alkenylation of pivalophenone N-H imine with alkenyl phosphates. Beilstein J Org Chem 2018; 14:709-715. [PMID: 29719569 PMCID: PMC5905286 DOI: 10.3762/bjoc.14.60] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 03/14/2018] [Indexed: 11/24/2022] Open
Abstract
A cobalt–N-heterocyclic carbene (NHC) catalyst efficiently promotes an ortho C–H alkenylation reaction of pivalophenone N–H imine with an alkenyl phosphate. The reaction tolerates various substituted pivalophenone N–H imines as well as cyclic and acyclic alkenyl phosphates.
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48
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Abstract
A cobalt catalyst enables directed ortho-methylation of arenes using readily available methyl tosylate as well as its deuterated analogue.
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Cobalt-catalyzed C(sp2)–H/C(sp3)–H coupling via directed C–H activation and 1,5-hydrogen atom transfer. Org Chem Front 2018. [DOI: 10.1039/c7qo00906b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A cobalt catalyst promotes C(sp2)–H/C(sp3)–H coupling through a merger of directed C(sp2)–H activation and 1,5-hydrogen atom transfer.
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Directed C-H Alkenylation of Aryl Imines with Alkenyl Phosphates Promoted by a Cobalt-N-Heterocyclic Carbene Catalyst. Adv Synth Catal 2017. [DOI: 10.1002/adsc.201701105] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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