Zhou Wei, Zhang Lei, Liu Dan-Yang, Ma Xiaosi, Zhang Jie, Kang Jiajia
School of Science, Tianjin Chengjian University, Tianjin 300384, China.
College of Chemistry, Beijing Normal University, Beijing 100875, China.
Molecules. 2025 Apr 23;30(9):1883. doi: 10.3390/molecules30091883.
Density functional theory calculations have been performed to explore the detailed mechanism of a ruthenium-catalyzed dehydrogenative annulation between α-carbonyl phosphonium ylide () and sulfoxonium ylide (). The proposed catalytic cycles consist of several elementary steps in succession, namely the C-H activation of ylide , the insertion of ylide , reductive elimination, protodemetallation, and an intramolecular Wittig reaction, in which C-H activation is rate-limiting, with a free energy barrier of 31.7 kcal/mol. As and are both capable of being a C-H activation substrate and a carbene precursor, there are potentially four competing pathways including homo-coupling reactions. Further calculations demonstrate that is more reactive in the C-H activation step than , while the opposite conclusion is true for the ylide insertion step, which can successfully explain the fact that the solely observed product originated from the use of as the C-H activation substrate and as the carbene precursor. Molecular electrostatic potential, charge decomposition, and electron density difference analyses were performed to understand the distinct behaviors of the two ylides and the nature of the key ruthenium-carbene intermediate.
已进行密度泛函理论计算，以探究钌催化的α-羰基鏻叶立德（）与亚砜叶立德（）之间脱氢环化反应的详细机理。所提出的催化循环由几个连续的基本步骤组成，即叶立德的C-H活化、叶立德的插入、还原消除、质子脱金属化以及分子内维蒂希反应，其中C-H活化是限速步骤，自由能垒为31.7 kcal/mol。由于和都能够作为C-H活化底物和卡宾前体，因此存在包括均偶联反应在内的四种潜在竞争途径。进一步的计算表明，在C-H活化步骤中比更具反应性，而在叶立德插入步骤中则得出相反的结论，这可以成功解释仅观察到的产物源自使用作为C-H活化底物和作为卡宾前体这一事实。进行了分子静电势、电荷分解和电子密度差分析，以了解两种叶立德的不同行为以及关键钌-卡宾中间体的性质。
