Synlett, Inhaltsverzeichnis Synlett 2015; 26(05): 619-624DOI: 10.1055/s-0034-1379954 letter © Georg Thieme Verlag Stuttgart · New York 1,1′-Methylene-3,3′-bis[(N-(tert-butyl)imidazol-2-ylidene] and Its Effect in Palladium-Catalyzed C–C Coupling Shirin Nadri a Faculty of Chemistry, Razi University, Kermanshah 67149, Iran eMail: mjoshaghani@razi.ac.ir , Ezzat Rafiee a Faculty of Chemistry, Razi University, Kermanshah 67149, Iran eMail: mjoshaghani@razi.ac.ir , Sirous Jamali b Chemistry Department, Sharif University Technology, P.O. Box 11155-3615, Tehran, Iran , Mohammad Joshaghani* a Faculty of Chemistry, Razi University, Kermanshah 67149, Iran eMail: mjoshaghani@razi.ac.ir › Institutsangaben Artikel empfehlen Abstract Artikel einzeln kaufen Alle Artikel dieser Rubrik Abstract A catalytic system utilizing a chelate carbene ligand containing bulk tert-butyl groups is described for palladium-catalyzed Heck and Suzuki coupling reactions. The Heck reaction focused on the coupling of different aryl bromides with mono- and 1,1-disubstituted olefins while the Suzuki reaction involved the coupling of aryl bromides and phenylboronic acid to afford the corresponding biphenyls. The catalyst system performs well with low Pd(OAc)2 levels (0.025 mol% Pd). In all cases with monosubstituted olefins, the trans-configured products were obtained, while the results of Heck reaction of 1,1-disubstituted olefins exhibited a high selectivity favoring the terminal product. Key words Key wordspalladium - carbene Ligand - C–C coupling - Heck reaction - Suzuki reaction Volltext Referenzen References and Notes 1 Budagumpi S, Haque RA, Washeel Salman A. Coord. Chem. Rev. 2012; 256: 1787 2 Herrmann WA. Angew. Chem. Int. Ed. 2002; 41: 1290 3 César V, Bellemin-Laponnaz S, Gade LH. Chem. Soc. Rev. 2004; 33: 619 4 McGuinness DS, Cavell KJ. Organometallics 1999; 18: 1596 5 Huynh HV, Ho JH. H, Neo TCh, Koh LL. J. Organomet. 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Acta 2000; 300–302: 958 30 General Procedure for the Suzuki Coupling A reaction tube was charged with PhB(OH)2 (4 mmol), aryl bromide (4 mmol), and K2CO3(4 mmol) under an air atmosphere. A solution of Pd(OAc)2 (0.025 mol% in 1 mL of DMF) along with a solution of NHC ligand 1 (0.05 mol% in 2 mL of DMF) was added through a rubber septum. After addition of H2O (1 mL), the resulting mixture was heated at 135 °C for the appropriate time. After extraction with Et2O, the organic phase was dried over MgSO4, filtered, the solvent evaporated, and the crude product was characterized by NMR spectroscopy. Zusatzmaterial Zusatzmaterial Supporting Information
