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Galiana-Cameo M, Borraz M, Zelenkova Y, Passarelli V, Lahoz FJ, Pérez-Torrente JJ, Oro LA, Di Giuseppe A, Castarlenas R. Rhodium(I)-NHC Complexes Bearing Bidentate Bis-Heteroatomic Acidato Ligands as gem-Selective Catalysts for Alkyne Dimerization. Chemistry 2020; 26:9598-9608. [PMID: 32374897 DOI: 10.1002/chem.202001584] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/24/2020] [Indexed: 02/06/2023]
Abstract
A series of Rh(κ2 -BHetA)(η2 -coe)(IPr) complexes bearing 1,3-bis-hetereoatomic acidato ligands (BHetA) including carboxylato (O,O), thioacetato (O,S), amidato (O,N), thioamidato (N,S), and amidinato (N,N), have been prepared by reaction of the dinuclear precursor [Rh(μ-Cl)(IPr)(η2 -coe)]2 with the corresponding anionic BHetA species. The RhI -NHC-BHetA compounds catalyze the dimerization of aryl alkynes, showing excellent selectivity for the head-to-tail enynes. Among them, the acetanilidato-based catalyst has shown an outstanding catalytic performance reaching unprecedented TOF levels of 2500 h-1 with complete selectivity for the gem-isomer. Investigation of the reaction mechanism supports a non-oxidative pathway in which the BHetA ligand behaves as proton shuttle through intermediate κ1 -HBHetA species. However, in the presence of pyridine as additive, the identification of the common RhIII H(C≡CPh)2 (IPr)(py)2 intermediate gives support for an alternative oxidative route.
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Affiliation(s)
- María Galiana-Cameo
- Departamento de Química Inorgánica-Instituto de, Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP., 50009, Zaragoza, Spain
| | - Marina Borraz
- Departamento de Química Inorgánica-Instituto de, Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP., 50009, Zaragoza, Spain
| | - Yaroslava Zelenkova
- Departamento de Química Inorgánica-Instituto de, Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP., 50009, Zaragoza, Spain
| | - Vincenzo Passarelli
- Departamento de Química Inorgánica-Instituto de, Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP., 50009, Zaragoza, Spain.,Centro Universitario de la Defensa, Ctra Huesca S/N, 50090, Zaragoza, Spain
| | - Fernando J Lahoz
- Departamento de Química Inorgánica-Instituto de, Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP., 50009, Zaragoza, Spain
| | - Jesús J Pérez-Torrente
- Departamento de Química Inorgánica-Instituto de, Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP., 50009, Zaragoza, Spain
| | - Luis A Oro
- Departamento de Química Inorgánica-Instituto de, Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP., 50009, Zaragoza, Spain
| | - Andrea Di Giuseppe
- Departamento de Química Inorgánica-Instituto de, Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP., 50009, Zaragoza, Spain
| | - Ricardo Castarlenas
- Departamento de Química Inorgánica-Instituto de, Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-CSIC, C/Pedro Cerbuna 12, CP., 50009, Zaragoza, Spain
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Ali TH, Heidelberg T, Hussen RSD, Tajuddin HA. Unexpected Reactions of Terminal Alkynes in Targeted "Click Chemistry'' Coppercatalyzed Azide-alkyne Cycloadditions. Curr Org Synth 2020; 16:1143-1148. [PMID: 31984920 DOI: 10.2174/1570179416666191105152714] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 09/24/2019] [Accepted: 10/01/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND High efficiency in terms of reaction yield and purity has led to the extensive utilization of copper-catalyzed azide-alkyne cycloaddition (CuAAC) in various fields of chemistry. Its compatibility with low molecular weight alcohols promotes the application in surfactant synthesis to tackle the miscibility constraints of the reactants. OBJECTIVE For the tuning of surfactant properties, double click coupling of the antipode precursors was attempted. Failure of the CuAAC to provide the targeted product in combination with unexpected reaction outputs led to an investigation of the side reaction. METHODS The CuAAC-based coupling of sugar azide with propargyl building block in the presence of copper- (I) catalyst exclusively led to the mono-coupling product in a respectable yield of almost 80%. Besides the unexpected incomplete conversion, the loss of the remaining propargyl group, as indicated by both NMR and MS. On the other hand, application of substantial amounts of CuSO4 under reducing conditions in refluxing toluene/water furnished the alkyne dimer in a moderate yield of 43%, while no change of azide compound was noticed. RESULTS The Cu(I)-catalyst applied for azide-alkyne cycloadditions enables the homo-coupling of certain terminal alkynes at a higher temperature. Moreover, aromatic propargyl ethers may be cleaved to furnish the corresponding phenol. The copper-catalyzed coupling appeared highly sensitive towards the alkyne compound. Only selected derivatives of propargyl alcohol were successfully dimerized. CONCLUSIONS The observed failure of the Huisgen reaction for the synthesis of sugar-based surfactants may indicate non-recognized constrains of the reaction, which could affect its wide application in bioconjugation. The temperature requirement for the alternative dimerization of terminal alkynes renders this side reaction nonrelevant for typical click couplings, while narrow substrate diversity and moderate yield limit its synthetic application.
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Affiliation(s)
- Tammar H Ali
- Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Thorsten Heidelberg
- Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Rusnah S D Hussen
- Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
| | - Hairul A Tajuddin
- Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia
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Zatolochnaya OV, Gordeev EG, Jahier C, Ananikov VP, Gevorgyan V. Carboxylate switch between hydro- and carbopalladation pathways in regiodivergent dimerization of alkynes. Chemistry 2014; 20:9578-88. [PMID: 25043968 DOI: 10.1002/chem.201402809] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Indexed: 11/11/2022]
Abstract
Experimental and theoretical investigation of the regiodivergent palladium-catalyzed dimerization of terminal alkynes is presented. Employment of N-heterocyclic carbene-based palladium catalyst in the presence of phosphine ligand allows for highly regio- and stereoselective head-to-head dimerization reaction. Alternatively, addition of carboxylate anion to the reaction mixture triggers selective head-to-tail coupling. Computational studies suggest that reaction proceeds via the hydropalladation pathway favoring head-to-head dimerization under neutral reaction conditions. The origin of the regioselectivity switch can be explained by the dual role of carboxylate anion. Thus, the removal of hydrogen atom by the carboxylate directs reaction from the hydropalladation to the carbopalladation pathway. Additionally, in the presence of the carboxylate anion intermediate, palladium complexes involved in the head-to-tail dimerization display higher stability compared to their analogues for the head-to-head reaction.
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Affiliation(s)
- Olga V Zatolochnaya
- Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois, 60607-7061 (USA)
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