Zhang Yan, Yang Yongsheng, Zhu Ruyu, Wang Xingyu, Xue Ying
Key Lab of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu, China.
Front Chem. 2019 Aug 23;7:586. doi: 10.3389/fchem.2019.00586. eCollection 2019.
N-O heterocycle compounds play an important role in various fields. Doyle et al. (Cheng et al., 2017) have recently reported an efficient catalyst-controlled selective cyclization reactions of -butyldimethylsilyl (TBS)-protected enoldiazoacetamides with nitrosoarenes in which the multifunctionalized products 5-isoxazolones and 1,3-oxazin-4-ones were formed through [3+2]- and [5+1]-cyclizations using Rh(oct) and Rh(cap) as catalysts, respectively. The present work studied the mechanism of the reactions in question and the origins of the catalyst-dependent chemoselectivity by the density functional theory (DFT) calculations at the M06-D3/SMD/6-311+G(d,p)//B3LYP-D3/6-31G(d,p) level of theory. The computed results illustrate the importance of the different dirhodium catalysts to gain diversified N-O heterocycle compounds and suggest the specific interaction between the reactants by the real catalyst model. Meanwhile, it is the steric hindrance and electronic effect of the ligands of dirhodium catalysts that control the reaction mechanism. Furthermore, the other auxiliary theoretical analysis, natural bond orbital calculation and distortion/interaction analysis, make the electronic effects, and steric hindrance more distinct.
N-O杂环化合物在各个领域都发挥着重要作用。多伊尔等人（程等人，2017年）最近报道了一种高效的催化剂控制的反应，即叔丁基二甲基甲硅烷基（TBS）保护的烯醇重氮乙酰胺与亚硝基芳烃的选择性环化反应，其中分别使用Rh(oct)和Rh(cap)作为催化剂，通过[3+2]环化和[5+1]环化形成了多功能化产物5-异恶唑酮和1,3-恶嗪-4-酮。本工作通过在M06-D3/SMD/6-311+G(d,p)//B3LYP-D3/6-31G(d,p)理论水平上的密度泛函理论（DFT）计算，研究了上述反应的机理以及催化剂依赖性化学选择性的起源。计算结果说明了不同的二铑催化剂对于获得多样化的N-O杂环化合物的重要性，并通过真实的催化剂模型表明了反应物之间的特定相互作用。同时，二铑催化剂配体的空间位阻和电子效应控制着反应机理。此外，其他辅助理论分析，自然键轨道计算和变形/相互作用分析，使电子效应和空间位阻更加明显。
