Heck reaction catalysed by pyridyl-imine palladium(0) and palladium(II) complexes
Heck reaction catalysed by pyridyl-imine palladium(0) and palladium(II) complexes
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DOI：
10.1016/j.molcata.2004.09.049
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发表时间：
2005-02-01
影响因子：
--
通讯作者：
Rogolino, D
中科院分区：
文献类型：
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作者：
Pelagatti, P;Carcelli, M;Rogolino, D
合成了三种含NN'吡啶亚胺配体的钯（II）配合物Pd（NN'）Cl-2和两种含NN'吡啶亚胺配体的钯（O）配合物Pd（NN'）（dmfu）（dmfu =富马酸二甲酯），并将其用作碘苯与丙烯酸甲酯（Meac）偶联（Heck反应）的预催化剂。所有反应均在DMF中在80 ℃下进行，使用Et 3 N作为碱，Pd：Ph 1：Meac：Et 3 N = 1：1000：1100：1000摩尔比。在所有情况下，碘苯完全转化为反式-甲基肉桂酸酯已被观察到在2.5小时内的反应，与最高的TOF值（1253）获得的钯（II）络合物。在催化反应结束时，回收了二聚物[Pd 2 I6][Et 3 NH]（2），指出了起始络合物的部分钯损失。Hg（0）中毒试验表明催化反应的非均相性质，这表明Pd（NN ′）配合物起金属钯库的作用。二聚体[Pd_2I_6][Et_3NH]（2）可能是由底物完全消耗后络合物分解产生的可溶性钯（0）颗粒形成的。有趣的是，二聚体[Pd_2I_6][DMFH]（2）是通过PdCl_2和Meac在DMF中于80 ℃反应得到的。(C)2004 Elsevier B. V.保留所有权利。
Three different palladium(II) complexes Pd(NN')Cl-2 and two different palladium(0) complexes Pd(NN')(dmfu) (dmfu = dimethylfumarate) containing NN' pyridyl-imine ligands, have been prepared and used as pre-catalysts for the coupling between iodobenzene and methyl acrylate (Meac) (Heck reaction). All the reactions have been conducted in DMF at 80degreesC, using Et3N as base and a Pd:Ph1: Meac:Et3N = 1:1000:1100:1000 molar ratio. In all cases the complete conversion of iodobenzene into trans-methylcynnamate has been observed within 2.5 h of reaction, with the highest TOF value (1253) obtained with a palladium(II) complex. At the end of the catalytic reactions the dimeric species [Pd2I6][Et3NH](2) has been recovered, pointing out a partial palladium loss from the starting complex species. A poisoning Hg(0) test has shown a heterogeneous nature of the catalytic reactions and this indicates that the Pd(NN') complexes act as metallic palladium reservoirs. The dimer [Pd2I6][Et3NH](2) probably forms from soluble palladium(0) particles arising from the complex decomposition once the substrates have been totally consumed. Interestingly, the dimer [Pd2I6][DMFH](2) has been obtained by reacting PdCl2 and Meac in DMF at 80degreesC. (C) 2004 Elsevier B.V. All rights reserved.