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首页> 外文期刊>Chemistry: A European journal >Why Platinum Catalysts Involving Ligands with Large Bite Angle Are so Efficient in the Allylation of Amines: Design of a Highly Active Catalyst and Comprehensive Experimental and DFT Study
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Why Platinum Catalysts Involving Ligands with Large Bite Angle Are so Efficient in the Allylation of Amines: Design of a Highly Active Catalyst and Comprehensive Experimental and DFT Study

机译：为什么涉及具有大咬合角的配体的铂催化剂在胺的烯丙基化中如此高效：高活性催化剂的设计以及全面的实验和DFT研究

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The platinum-catalyzed allylation of amines with allyl alcohols was studied experimentally and theoretically. The complexes [Pt(eta(3)-allyl)-(dppe)]OTf (2) and [Pt(eta(3)-allyl)(DPP-Xantphos)]PF6 (5) were synthesized and structurally characterized, and their reactivity toward amines was explored. The bicyclic aminopropyl complex [Pt(CH,CH2CH2NH2NHBn-kappa-C,N)-(dppe)]OTf (3) was obtained from the reaction of complex 2 with an excess of benzylamine, and this complex was shown to be a deactivated form of catalyst 2. On the other hand, reaction of complex 5 with benzylamine and allyl alcohol led to formation of the 16-VE platinum(0) complex [Pt(eta(2)-C3H5OH)-(DPP-Xantphos)] (7), which was structurally characterized and appears to be a catalytic intermediate. A DFT study showed that the mechanism of the platinum-catalyzed allylation of amines with allyl alcohols differs from the palladium-catalyzed process, since it involves an associative ligand-exchange step involving formation of a tetracoordinate 18-VE complex. This DFT study also revealed that ligands with large bite angles disfavor the formation of platinum hydride complexes and therefore the formation of a bicyclic aminopropyl complex, which is a thermodynamic sink. Finally, a combination of 5 and a proton source was shown to efficiently catalyze the allylation of a broad variety of amines with allyl alcohols under mild conditions.
机译：通过实验和理论研究了铂与烯丙醇催化的胺基烯丙基化反应。合成[Pt（eta（3）-烯丙基）-（dppe）] OTf（2）和[Pt（eta（3）-烯丙基）（DPP-Xantphos）] PF6（5）并对其结构进行表征，探索了对胺的反应性。双环氨基丙基配合物[Pt（CH，CH2CH2NH2NHBn-k，N）-（dppe）] OTf（3）由配合物2与过量的苄胺反应制得，该配合物显示为失活形式另一方面，配合物5与苄胺和烯丙醇的反应导致形成16-VE铂（0）配合物[Pt（eta（2）-C3H5OH）-（DPP-Xantphos）]（7 ），具有结构特征，似乎是催化中间体。 DFT研究表明，胺与烯丙醇的铂催化胺化烯丙基化的机理与钯催化过程不同，因为它涉及缔合配体交换步骤，该步骤涉及形成四配位18-VE络合物。这项DFT研究还显示，具有较大咬合角的配体不利于氢化铂配合物的形成，因此不利于双环氨基丙基配合物的形成，而后者是热力学沉陷。最后，显示5和质子源的组合可在温和条件下有效催化多种胺与烯丙醇的烯丙基化反应。

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