Palladium mediated C-H bond activation of thiosemicarbazones: Catalytic application of organopalladium complexes in C-C and C-N coupling reactions

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• 作者：Piyali Paul ; Poulami Sengupta ; Samaresh Bhattacharya ; ^{samaresh_b@hotmail.com}
• 关键词：Thiosemicarbazones ; C&ndash ; H bond activation ; Organopalladium complexes ; C&ndash ; C coupling reactions ; C&ndash ; N coupling reactions
• 刊名：Journal of Organometallic Chemistry
• 出版年：2013
• 出版时间：15 January, 2013
• 年：2013
• 卷：724
• 期：Complete
• 页码：281-288
• 全文大小：591 K

文摘

Upon reaction with Pd(PPh₃)₂Cl₂ benzaldehyde thiosemicarbazone undergoes a geometrical change around the imine bond and affords a mixed-ligand complex 1, incorporating an NS-coordinated thiosemicarbazone, a triphenylphosphine and a chloride. Similar reactions with benzophenone thiosemicarbazone and acetophenone thiosemicarbazone proceed without any geometrical change to afford complexes 2 and 3 respectively, containing a CNS-coordinated thiosemicarbazone and a triphenylphosphine. Crystal structures of complexes 1, 2 and 3 have been determined. All the complexes display?intense absorptions in the visible region. Catalytic activity of complexes 1, 2 and 3 toward Suzuki type C-C coupling reactions has been examined, and all three are found to efficiently activate all types of C-X bonds (X?=?I, Br, Cl and even F) and bring about the C-C bond formation with high yield. These complexes are also found to catalyze C-N coupling reactions between aryl halides and primary or secondary amines. While all three complexes are found to be efficient catalysts for both C-C and C-N coupling reactions, complex 2 is found to be a better catalyst than the other two complexes.