Mechanistic Insight into the Copper-Catalyzed Phosphorylation of Terminal Alkynes: A Combined Theoretical and Experimental Study
Mechanistic Insight into the Copper-Catalyzed Phosphorylation of Terminal Alkynes: A Combined Theoretical and Experimental Study
复制标题
铜催化末端炔烃磷酸化的机理洞察：理论与实验相结合的研究
DOI：
10.1021/jo5007174
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发表时间：
2014-08-01
影响因子：
3.6
通讯作者：
Zhao, Yufen
中科院分区：
文献类型：
--
作者：
Liu, Liu;Wu, Yile;Zhao, Yufen
对不同条件下铜催化末端炔烃磷酸化的反应机理进行了实验和理论研究。氧的重要作用已被阐明，包括形成ETA(1)-超氧铜(II)、ETA(2)-超氧铜(III)、Mu-ETA(2)：ETA(2)-过氧二铜(II)和双(MU-OX)二铜(III)络合物。更重要的是，从亚磷酸二烷基磷酸盐到桥氧原子的质子转移导致去质子化的磷酸盐迁移到末端的炔基上，导致C-P键的形成，活化势垒仅为1.8kcal/mol。此外，随着两个Ph_2P(O)基团从铜原子迁移到双(Mu-oxo)桥的氧原子，形成了一个特别稳定的六中心双铜(I)物种，解释了实验观察到的仲膦氧化物可以被氧化成膦酸。因此，将二苯基氧化膦滴加到反应混合物中，以使反应过程中的浓度降至最低。令人满意的是，当反应完成时，偶联产物几乎是定量产生的。
The reaction mechanism of copper-catalyzed phosphorylation of terminal alkynes under different conditions has been investigated experimentally and theoretically. The important role of dioxygen has been elucidated, including the formation of eta(1)-superoxocopper(II), eta(2)-superoxocopper(III), mu-eta(2):eta(2)-peroxodicopper(II), and bis(mu-oxo)dicopper(III) complexes. More importantly, the proton transfer from the dialkyl phosphonate (in the form of phosphite) to the bridging oxygen atom entails the migration of the deprotonated phosphonate to the terminal alkyne, leading to the formation of a C-P bond with an activation barrier of only 1.8 kcal/mol. In addition, a particularly stable six-centered dicopper(I) species is formed with the migration of both of the Ph2P(O) groups from the copper atoms to the oxygen atoms of the bis(mu-oxo) bridge, explaining the experimental observation that secondary phosphine oxides can be oxidized to the phosphinic acids. Thus, the diphenylphosphine oxide was added to the reaction mixture dropwise to minimize the concentration during the reaction course. Gratifyingly, the coupling product was generated almost quantitatively when the reaction was completed.