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Pirovano V, Abbiati G, Brambilla E, Rossi E. Vinyl‐/Furoindoles and Gold Catalysis: New Achievements and Future Perspectives for the Synthesis of Complex Indole Derivatives. Eur J Inorg Chem 2019. [DOI: 10.1002/ejic.201901044] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Valentina Pirovano
- Sezione di Chimica Generale e Organica “A. Marchesini” Dipartimento di Scienze Farmaceutiche 21, Via Venezian 20133 Milano Italy
| | - Giorgio Abbiati
- Sezione di Chimica Generale e Organica “A. Marchesini” Dipartimento di Scienze Farmaceutiche 21, Via Venezian 20133 Milano Italy
| | - Elisa Brambilla
- Sezione di Chimica Generale e Organica “A. Marchesini” Dipartimento di Scienze Farmaceutiche 21, Via Venezian 20133 Milano Italy
| | - Elisabetta Rossi
- Sezione di Chimica Generale e Organica “A. Marchesini” Dipartimento di Scienze Farmaceutiche 21, Via Venezian 20133 Milano Italy
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2
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Alonso JM, Muñoz MP. Platinum and Gold Catalysis: à la Carte Hydroamination of Terminal Activated Allenes with Azoles. Org Lett 2019; 21:7639-7644. [DOI: 10.1021/acs.orglett.9b02949] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- José Miguel Alonso
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - María Paz Muñoz
- School of Chemistry, University of East Anglia, Norwich NR4 7TJ, United Kingdom
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3
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Praveen C. Dexterity of gold catalysis in controlling the regioselectivity of cycloaddition reactions. CATALYSIS REVIEWS-SCIENCE AND ENGINEERING 2019. [DOI: 10.1080/01614940.2019.1594016] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Chandrasekar Praveen
- Materials Electrochemistry Division, Central Electrochemical Research Institute (CSIR Laboratory), Karaikudi, Tamil Nadu, India
- Academy of Scientific and Innovative Research (AcSIR), Central Electrochemical Research Institute (CSIR Laboratory), Karaikudi, Tamil Nadu, India
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4
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Mascareñas JL, Varela I, López F. Allenes and Derivatives in Gold(I)- and Platinum(II)-Catalyzed Formal Cycloadditions. Acc Chem Res 2019; 52:465-479. [PMID: 30640446 PMCID: PMC6497370 DOI: 10.1021/acs.accounts.8b00567] [Citation(s) in RCA: 148] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Indexed: 12/17/2022]
Abstract
Cycloaddition reactions, by involving the formation of at least two bonds and one cycle in a single operation, represent one of the more practical ways to assemble carbo- and heterocyclic structures from simple acyclic precursors. Especially appealing are formal cycloadditions promoted by transition metals, owing to the ability of these reagents to open mechanisms that are not accessible using classical chemistry. Therefore, along the years, a great variety of annulations based on first-, and particularly second-row transition metals have been discovered. Most of these reactions involve inner sphere mechanisms, with the metal participating via standard oxidative addition or reductive elimination processes. Curiously, metals of the third row like platinum and, especially, gold remained largely unexplored, likely because of the belief that they were inert and expensive. However, from the beginning of this century, many groups realized that these metals can open very interesting mechanistic scenarios and promote novel types of transformations. In particular, the π-acidic, carbophilic behavior of gold(I) complexes, together with the possibility of tuning their reactivity using designed ligands, has triggered important activity in the field. Many gold-catalyzed transformations involved addition or cycloisomerization processes, but during recent years, there have been also important advances in the development of formal cycloaddition reactions. While many of these reactions rely on the activation of alkynes, there has been an increasing number of reports that exploit the peculiar reactivities of allenes and derivatives. In this Account, we present recent efforts on the development of platinum- and gold-catalyzed formal cycloadditions of allenes. For the sake of simplicity, we only include annulations initiated by a direct metal-promoted activation of the allene moiety. Thus, alternative Pt- or Au-catalyzed reactions wherein the allene does not interact with the metal catalyst are not covered. Upon activation by the metals, allenes generate allyl-cation alkenylmetal species that can behave as 1,2- or 1,3-carbon dipoles in cycloaddition processes. Especially relevant is the reactivity of allenamides. The presence of the amide substituent provides for the generation of gold intermediates with a good balance of reactivity and stability, which can therefore react with the corresponding partners in a controlled manner. Moreover, despite the difficulties associated with the transfer of stereochemical information from chiral linear gold(I) complexes, a variety of enantioselective gold-catalyzed annulations have been discovered. This Account is organized considering the number of atoms engaged in the annulation process, and when possible, we present the results in a chronological order.
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Affiliation(s)
- José L. Mascareñas
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CiQUS) and Departamento de Química
Orgánica, Universidad de Santiago
de Compostela, 15782 Santiago de Compostela, Spain
| | - Iván Varela
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CiQUS) and Departamento de Química
Orgánica, Universidad de Santiago
de Compostela, 15782 Santiago de Compostela, Spain
| | - Fernando López
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CiQUS) and Departamento de Química
Orgánica, Universidad de Santiago
de Compostela, 15782 Santiago de Compostela, Spain
- Instituto
de Química Orgánica General, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain
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5
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Wu Q, Shao PL, He Y. Synthesis of 1,4,5,6-tetrahydropyridazines and pyridazines via transition-metal-free (4 + 2) cycloaddition of alkoxyallenes with 1,2-diaza-1,3-dienes. RSC Adv 2019; 9:21507-21512. [PMID: 35521294 PMCID: PMC9066181 DOI: 10.1039/c9ra02712b] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 07/04/2019] [Indexed: 12/19/2022] Open
Abstract
We developed an economical and practical protocol for the synthesis of 1,4,5,6-tetrahydropyridazines. A diverse range of alkoxyallenes and 1,2-diaza-1,3-dienes undergo (4 + 2) cycloaddition to generate the desired products in excellent yields. The high efficiency, wide substrate scope and good functional group tolerance of this process, coupled with operational simplicity, render the method synthetically attractive. The utility of the cycloaddition is also demonstrated by the preparation of various pyridazines from 1,4,5,6-tetrahydropyridazines. We developed an economical and practical protocol for the synthesis of 1,4,5,6-tetrahydropyridazines and pyridazines via cyclization of alkoxyallenes and 1,2-diaza-1,3-dienes.![]()
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Affiliation(s)
- Qi Wu
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research
- School of Pharmaceutical Sciences
- Chongqing University
- Chongqing 401331
- People's Republic of China
| | - Pan-Lin Shao
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research
- School of Pharmaceutical Sciences
- Chongqing University
- Chongqing 401331
- People's Republic of China
| | - Yun He
- Chongqing Key Laboratory of Natural Product Synthesis and Drug Research
- School of Pharmaceutical Sciences
- Chongqing University
- Chongqing 401331
- People's Republic of China
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6
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Pirovano V, Borri M, Abbiati G, Rizzato S, Rossi E. Gold(I)-Catalyzed Enantioselective Synthesis of Tetrahydrocarbazoles through Dearomative [4+2] Cycloadditions of 3/2-Substituted 2/3-Vinylindoles. Adv Synth Catal 2017. [DOI: 10.1002/adsc.201700280] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Valentina Pirovano
- Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Generale e Organica “A. Marchesini”; Università degli Studi di Milano; Via Venezian 21 20133 Milano Italy
| | - Micol Borri
- Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Generale e Organica “A. Marchesini”; Università degli Studi di Milano; Via Venezian 21 20133 Milano Italy
| | - Giorgio Abbiati
- Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Generale e Organica “A. Marchesini”; Università degli Studi di Milano; Via Venezian 21 20133 Milano Italy
| | - Silvia Rizzato
- Dipartimento di Chimica; Università degli Studi di Milano; Via Golgi 19 20133 Milano Italy
| | - Elisabetta Rossi
- Dipartimento di Scienze Farmaceutiche, Sezione di Chimica Generale e Organica “A. Marchesini”; Università degli Studi di Milano; Via Venezian 21 20133 Milano Italy
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7
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Kona CN, Shinde MH, Ramana CV. Gold(i)-catalyzed hydroindolylation of allenyl ethers. Org Biomol Chem 2015; 13:5358-62. [DOI: 10.1039/c5ob00635j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nucleophilicity game: the gold(i)-catalyzed reaction/rearrangement of allenyl ethers has been investigated in the presence of indoles. The reaction outcome seems to be decided mainly by the nature of the pendant group of allenyl ether. Control experiments are indicative of an inner sphere mechanism for the hydroindolylation reaction.
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Affiliation(s)
| | - Mahesh H. Shinde
- Division of Organic Chemistry
- CSIR-National Chemical Laboratory
- Pune 411008
- India
| | - Chepuri V. Ramana
- Division of Organic Chemistry
- CSIR-National Chemical Laboratory
- Pune 411008
- India
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8
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Muratore ME, Homs A, Obradors C, Echavarren AM. Meeting the challenge of intermolecular gold(I)-catalyzed cycloadditions of alkynes and allenes. Chem Asian J 2014; 9:3066-82. [PMID: 25048645 PMCID: PMC4676923 DOI: 10.1002/asia.201402395] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Indexed: 12/11/2022]
Abstract
The development of gold(I)-catalyzed intermolecular carbo- and hetero-cycloadditions of alkynes and allenes has been more challenging than their intramolecular counterparts. Here we review, with a mechanistic perspective, the most fundamental intermolecular cycloadditions of alkynes and allenes with alkenes.
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Affiliation(s)
- Michael E Muratore
- Institute of Chemical Research of Catalonia (ICIQ)Av. Països Catalans 16, 43007 Tarragona (Spain)
| | - Anna Homs
- Institute of Chemical Research of Catalonia (ICIQ)Av. Països Catalans 16, 43007 Tarragona (Spain)
| | - Carla Obradors
- Institute of Chemical Research of Catalonia (ICIQ)Av. Països Catalans 16, 43007 Tarragona (Spain)
| | - Antonio M Echavarren
- Institute of Chemical Research of Catalonia (ICIQ)Av. Països Catalans 16, 43007 Tarragona (Spain)
- Departament de Química Analítica i Química OrgànicaUniversitat Rovira i Virgili, C/Marcel⋅lí Domingo s/n, 43007 Tarragona (Spain)
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9
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Sabbatani J, Huang X, Veiros LF, Maulide N. Gold-catalyzed intermolecular synthesis of alkylidenecyclopropanes through catalytic allene activation. Chemistry 2014; 20:10636-9. [PMID: 24976605 DOI: 10.1002/chem.201402935] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Indexed: 11/09/2022]
Abstract
A stereoselective gold(I)-catalyzed intermolecular cyclopropanation of allenamides with stabilized sulfonium ylides is reported. This transformation enables the direct synthesis of diacceptor alkylidenecyclopropanes and proceeds under very mild conditions through allene activation.
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Affiliation(s)
- Juliette Sabbatani
- Faculty of Chemistry, Institute of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna (Austria)
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10
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Abstract
Alkoxyallenes are unusually versatile C3 building blocks in organic synthesis. Hence this tutorial review summarizes the most important transformations, including subsequent reactions and their applications in the synthesis of relevant compounds, e.g. natural products. The reactivity patterns involved and the synthons derived from alkoxyallenes are presented. Often alkoxyallenes can serve as substitutes of acrolein or acrolein acetals, utilisation of which has already led to interesting products. Most important is the use of lithiated alkoxyallenes which smoothly react with a variety of electrophiles and lead to products with unique substitution patterns. The heterocycles or carbocycles formed are intermediates for the stereoselective synthesis of natural products or for the preparation of other structurally relevant compounds. The different synthons being put into practice by the use of lithiated alkoxyallenes in these variations will be discussed.
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Affiliation(s)
- Reinhold Zimmer
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany.
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11
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Abstract
This review summarizes the different catalytic [4+2] and [4+3] cycloadditions that have been developed by using allenes as 2C, 3C or even 4C atom partners.
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Affiliation(s)
- Fernando López
- Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS) and Departamento de Química Orgánica
- Universidade de Santiago de Compostela
- Santiago de Compostela, Spain
- Instituto de Química Orgánica General (CSIC)
- Madrid, Spain
| | - José L. Mascareñas
- Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS) and Departamento de Química Orgánica
- Universidade de Santiago de Compostela
- Santiago de Compostela, Spain
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12
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López F, Mascareñas JL. Gold(I)-catalyzed enantioselective cycloaddition reactions. Beilstein J Org Chem 2013; 9:2250-64. [PMID: 24204438 PMCID: PMC3817474 DOI: 10.3762/bjoc.9.264] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/26/2013] [Indexed: 12/20/2022] Open
Abstract
In recent years there have been extraordinary developments of gold(I)-catalyzed enantioselective processes. This includes progress in the area of cycloaddition reactions, which are of particular interest due to their potential for the rapid construction of optically active cyclic products. In this article we will summarize some of the most remarkable examples, emphasizing reaction mechanisms and key intermediates involved in the processes.
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Affiliation(s)
- Fernando López
- Instituto de Química Orgánica General, CSIC and Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS). Universidade de Santiago de Compostela, 15782, Santiago de Compostela, Spain
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13
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Montserrat S, Faustino H, Lledós A, Mascareñas JL, López F, Ujaque G. Mechanistic intricacies of gold-catalyzed intermolecular cycloadditions between allenamides and dienes. Chemistry 2013; 19:15248-60. [PMID: 24114995 DOI: 10.1002/chem.201302330] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Indexed: 11/07/2022]
Abstract
The mechanism of the gold-catalyzed intermolecular cycloaddition between allenamides and 1,3-dienes has been explored by means of a combined experimental and computational approach. The formation of the major [4+2] cycloaddition products can be explained by invoking different pathways, the preferred ones being determined by the nature of the diene (electron neutral vs. electron rich) and the type of the gold catalyst (AuCl vs. [IPrAu](+), IPr=1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene). Therefore, in reactions catalyzed by AuCl, electron-neutral dienes favor a concerted [4+3] cycloaddition followed by a ring contraction event, whereas electron-rich dienes prefer a stepwise cationic pathway to give the same type of formal [4+2] products. On the other hand, the theoretical data suggest that by using a cationic gold catalyst, such as [IPrAuCl]/AgSbF6, the mechanism involves a direct [4+2] cycloaddition between the diene and the gold-activated allenamide. The theoretical data are also consistent with the observed regioselectivity as well as with the high selectivity towards the formation of the enamide products with a Z configuration. Finally, our data also explain the formation of the minor [2+2] products that are obtained in certain cases.
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Affiliation(s)
- Sergi Montserrat
- Departament de Química, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)
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14
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Pirovano V, Decataldo L, Rossi E, Vicente R. Gold-catalyzed synthesis of tetrahydrocarbazole derivatives through an intermolecular cycloaddition of vinyl indoles and N-allenamides. Chem Commun (Camb) 2013; 49:3594-6. [PMID: 23525361 DOI: 10.1039/c3cc41514g] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A gold-catalyzed formal [4+2] cycloaddition of vinyl indoles and N-allenamides leading to tetrahydrocarbazoles is described. Moreover, new multicomponent reactions of vinyl indoles with two allene molecules are reported.
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Affiliation(s)
- Valentina Pirovano
- Instituto Universitario de Química Organometálica Enrique Moles and Departamento de Química Orgánica e Inorgánica, Universidad de Oviedo, c/Julián Clavería 8, 33007 Oviedo, Spain
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15
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Faustino H, Alonso I, Mascareñas JL, López F. Gold(I)-Catalyzed Cascade Cycloadditions between Allenamides and Carbonyl-Tethered Alkenes: An Enantioselective Approach to Oxa-Bridged Medium-Sized Carbocycles. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201302713] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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16
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Faustino H, Alonso I, Mascareñas JL, López F. Gold(I)-Catalyzed Cascade Cycloadditions between Allenamides and Carbonyl-Tethered Alkenes: An Enantioselective Approach to Oxa-Bridged Medium-Sized Carbocycles. Angew Chem Int Ed Engl 2013; 52:6526-30. [DOI: 10.1002/anie.201302713] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Indexed: 11/06/2022]
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17
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Francos J, Grande-Carmona F, Faustino H, Iglesias-Sigüenza J, Díez E, Alonso I, Fernández R, Lassaletta JM, López F, Mascareñas JL. Axially chiral triazoloisoquinolin-3-ylidene ligands in gold(I)-catalyzed asymmetric intermolecular (4 + 2) cycloadditions of allenamides and dienes. J Am Chem Soc 2012; 134:14322-5. [PMID: 22892048 DOI: 10.1021/ja3065446] [Citation(s) in RCA: 154] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The first highly enantioselective intermolecular (4 + 2) cycloaddition between allenes and dienes is reported. The reaction provides good yields of optically active cyclohexenes featuring diverse substitution patterns and up to three stereocenters. Key to the success of the process is the use of newly designed axially chiral N-heterocyclic carbene-gold catalysts.
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Affiliation(s)
- Javier Francos
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares and Departamento de Química Orgánica, Unidad Asociada al CSIC, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain
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18
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Garayalde D, Nevado C. Gold-Containing and Gold-Generated 1,n-Dipoles as Useful Platforms toward Cycloadditions and Cyclizations. ACS Catal 2012. [DOI: 10.1021/cs300043w] [Citation(s) in RCA: 180] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- David Garayalde
- Organic Chemistry
Institute, University of Zürich, Winterthurerstrasse 190, CH-8057,
Zürich, Switzerland
| | - Cristina Nevado
- Organic Chemistry
Institute, University of Zürich, Winterthurerstrasse 190, CH-8057,
Zürich, Switzerland
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19
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Faustino H, Bernal P, Castedo L, López F, Mascareñas JL. Gold(I)-Catalyzed Intermolecular [2+2] Cycloadditions between Allenamides and Alkenes. Adv Synth Catal 2012. [DOI: 10.1002/adsc.201200047] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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20
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Lin R, Zhao J, Chen H, Zhang H, Xia H. Interconversion of Metallabenzenes and Cyclic η
2
‐Allene‐Coordinated Complexes. Chem Asian J 2012; 7:1915-24. [DOI: 10.1002/asia.201200231] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Revised: 04/15/2012] [Indexed: 12/12/2022]
Affiliation(s)
- Ran Lin
- State Key Laboratory for Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (P.R. China), Fax: (+86) 592‐2186628
| | - Jing Zhao
- State Key Laboratory for Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (P.R. China), Fax: (+86) 592‐2186628
| | - Hanyu Chen
- State Key Laboratory for Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (P.R. China), Fax: (+86) 592‐2186628
| | - Hong Zhang
- State Key Laboratory for Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (P.R. China), Fax: (+86) 592‐2186628
| | - Haiping Xia
- State Key Laboratory for Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (P.R. China), Fax: (+86) 592‐2186628
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21
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Montserrat S, Alonso I, López F, Mascareñas JL, Lledós A, Ujaque G. Theoretical study on intramolecular allene-diene cycloadditions catalyzed by PtCl2 and Au(I) complexes. Dalton Trans 2011; 40:11095-105. [PMID: 21897964 DOI: 10.1039/c1dt11061f] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The intramolecular [4C+3C] cycloaddition reaction of allenedienes catalysed by PtCl(2) and several Au(I) complexes has been studied by means of DFT calculations. Overall, the reaction mechanism comprises three main steps: (i) the formation of a metal allyl cation intermediate, (ii) a [4C(4π)+3C(2π)] cycloaddition that produces a seven-membered ring and (iii) a 1,2-hydrogen migration process on these intermediates. The reaction proceeds with complete diastereochemical control resulting from a favoured exo-like cycloaddition. Allene substituents have a critical influence in the reaction outcome and mechanism. The experimental observation of [4C+2C] cycloadducts in the reaction of substrates lacking substituents at the allene terminus can be explained through a mechanism involving Pt(IV)-metallacycles. With gold catalysts it is also possible to obtain [4C+2C] cycloaddition products, but only with substrates featuring terminally disubstituted allenes, and employing π-acceptor ligands at gold. However the mechanism for the formation of these adducts is completely different to that proposed with PtCl(2), and consists of the formation of a metal allyl cation, subsequent [4C+3C] cycloaddition and a 1,2-alkyl shift (ring contraction). Electronic analysis indicates that the divergent pathways are mainly controlled by the electronic properties of the gold heptacyclic species (L-Au-C(2)), in particular, the backdonation capacity of the metal center to the unoccupied C(2) (pπ-orbital) of the intermediate resulting from the [4C+3C] cycloaddition. The less backdonation, (i.e. using P(OR)(3)Au(+) complexes), the more favoured is the 1,2-alkyl shift.
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Affiliation(s)
- Sergi Montserrat
- Departament de Química, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Spain
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22
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López F, Mascareñas JL. Recent developments in gold-catalyzed cycloaddition reactions. Beilstein J Org Chem 2011; 7:1075-94. [PMID: 21915211 PMCID: PMC3167873 DOI: 10.3762/bjoc.7.124] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 07/14/2011] [Indexed: 12/04/2022] Open
Abstract
In the last years there have been extraordinary advances in the development of gold-catalyzed cycloaddition processes. In this review we will summarize some of the most remarkable examples, and present the mechanistic rational underlying the transformations.
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Affiliation(s)
- Fernando López
- Instituto de Química Orgánica General, CSIC, C/ Juan de la Cierva 3, 28006, Madrid, Spain, (+) 34 915622900
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