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Substituted (pyridinyl)benzoazole palladium complexes: Synthesis and application as Heck coupling catalysts |
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| Authors: | Stephen O Ojwach Gunnar Westman James Darkwa |
| Institution: | aDepartment of Chemistry, University of Johannesburg, Auckland Park Kingsway Campus, Auckland Park 2006, South Africa bDepartment of Organic Chemistry, Chalmers University of Technology, S-412 96 Goteborg, Sweden |
| Abstract: | The synthesis of 2-(4-tert-butylpyridin-2-yl)-benzooxazole (L3), 2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L4) and 6-tert-Butyl-2-(4-tert-butyl-pyridin-2-yl)-benzothiazole (L5) by intramolecular cyclization under basic conditions is described. Reactions of 2-pyridin-2-yl-1H-benzoimidazole (L1), 2-pyridin-2-yl-benzothiazole (L2) and L3–L5 with either Pd(NCMe)2Cl2] or Pd(COD)MeCl] afforded the corresponding mononuclear palladium complexes Pd(L1)MeCl] (1), Pd(L2)MeCl] (2), Pd(L3)Cl2] (3), Pd(L3)MeCl] (4), Pd(L4)Cl2] (5), Pd(L4)MeCl] (6) and Pd(L4)MeCl] (7) as confirmed by mass spectrometry and elemental analyses. The palladium complexes are efficient Heck coupling catalysts for the reaction of iodobenzene with butylacrylate under mild conditions. Benzothiazole and benzooxazole containing complexes show faster induction periods compared to the benzoimidazole analogues. |
| Keywords: | Benzoazoles ligands Palladium complexes Catalysts Heck coupling reactions |
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