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首页> 外文期刊>Chemistry: A European journal >Mononuclear or Dinuclear? Mechanistic Study of the Zinc- Catalyzed Oxidative Coupling of Aldehydes and Acetylenes
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Mononuclear or Dinuclear? Mechanistic Study of the Zinc- Catalyzed Oxidative Coupling of Aldehydes and Acetylenes

机译：单核或二维？ 醛和乙炔锌催化氧化偶联的机械研究

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Although zinc catalysis is widely used in organic synthesis, very few studies on the dinuclear zinc mechanism have been reported. Here, a dinuclear zinc pathway is proposed for the Zn(OTf)_2-catalyzed oxidative coupling of aldehydes with terminal alkynes. DFT calculations revealed that the deprotonation of the terminal alkyne would preferentially lead to the formation of a dinuclear zinc intermediate. The nucleophilic addition of this intermediate to an aldehyde, followed by an Oppenauer-type oxidation was investigated theoretically according to the mono- and dinuclear pathways. The formation of a dinuclear zinc intermediate from a mononuclear alkynyl zinc complex was exergonic, favoring the dinuclear zinc pathway. The subsequent protonation and regeneration of the active dinuclear catalyst were also evaluated by DFT calculations. The oxidizabilities of various aldehydes and ketones were evaluated to determine the best oxidant for this step. Trifluoroacetaldehyde was predicted to be a better oxidant for this reaction because its calculated energy barrier for the Oppenauer-type oxidation step was much lower than that of the other carbonyl complexes.
机译：虽然锌催化广泛用于有机合成中，但据报道了对硫核锌机制的几乎没有研究。在此，提出了用末端炔醇醛的Zn（OTF）_2催化氧化偶联的氧化锆途径。 DFT计算显示，炔烃的去质子化将优先导致形成硫核锌中间体。根据单核途径理论上，从理论上研究了这种中间体对醛的亲核加入该中间体，然后进行对比氧化。从单核炔基锌络合物中中间体的形成是外核锌途径，有利于透明锌途径。通过DFT计算评估了活性二核催化剂的随后的质子化和再生。评估各种醛和酮的氧化性以确定该步骤的最佳氧化剂。预计三氟甲酰基甲醛是对该反应的更好的氧化剂，因为其对对手型氧化步骤的计算能屏障远低于其他羰基络合物的能量屏障。

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