CpRuCl(PPh )/MeI催化的降冰片二烯-炔环加成反应的多途径后续化学选择性
Multi-Pathway Consequent Chemoselectivities of CpRuCl(PPh ) /MeI-Catalysed Norbornadiene Alkyne Cycloadditions.
作者信息
Mu Wei-Hua, Fang De-Cai, Xia Shu-Ya, Cheng Rui-Jiao, Chass Gregory A
机构信息
Faculty of Chemistry and Chemical Engineering, Yunnan Normal University, NO. 298, Yieryi Street, Kunming, 650092, P. R. China.
College of Chemistry, Beijing Normal University, NO. 19, Xinjiekouwai Street, Beijing, 100875, P. R. China.
出版信息
Chemistry. 2016 Oct 17;22(43):15396-15403. doi: 10.1002/chem.201603173. Epub 2016 Sep 13.
Chemoselectivities of five experimentally realised CpRuCl(PPh ) /MeI-catalysed couplings of 7-azabenzo-norbornadienes with selected alkynes were successfully resolved from multiple reaction pathway models. Density functional theory calculations showed the following mechanistic succession to be energetically plausible: (1) CpRuI catalyst activation; (2) formation of crucial metallacyclopentene intermediate; (3) cyclobutene product (P2) elimination (ΔG ≈11.9-17.6 kcal mol ). Alternative formation of dihydrobenzoindole products (P1) by isomerisation to azametalla-cyclohexene followed by subsequent CpRuI release was much less favourable (ΔG ≈26.5-29.8 kcal mol ). Emergent stereoselectivities were in close agreement with experimental results for reactions a, b, e. Consequent investigations employing dispersion corrections similarly support the empirical findings of P1 dominating in reactions c and d through P2→P1 product transformations as being probable (ΔG≈25.3-30.1 kcal mol ).
通过多个反应途径模型成功解析了五种通过实验实现的CpRuCl(PPh₃)/MeI催化的7-氮杂苯并降冰片二烯与特定炔烃的偶联反应的化学选择性。密度泛函理论计算表明，以下反应机理顺序在能量上是合理的：(1)CpRuI催化剂活化；(2)关键的金属环戊烯中间体形成；(3)环丁烯产物(P2)消除(ΔG≈11.9 - 17.6 kcal·mol⁻¹)。通过异构化为氮杂金属环己烯随后释放CpRuI来形成二氢苯并吲哚产物(P1)的替代途径则不太有利(ΔG≈26.5 - 29.8 kcal·mol⁻¹)。出现的立体选择性与反应a、b、e的实验结果密切一致。随后采用色散校正的研究同样支持了在反应c和d中P1通过P2→P1产物转化占主导的实验结果是可能的(ΔG≈25.3 - 30.1 kcal·mol⁻¹)。
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