Cao Shanshan, Yuan Haiyan, Yang Yang, Wang Mang, Zhang Xiaoying, Zhang Jingping
Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Advanced Energy Materials Research Center, Faculty of Chemistry Northeast Normal University Changchun, 130024, China.
J Comput Chem. 2017 Oct 5;38(26):2268-2275. doi: 10.1002/jcc.24877. Epub 2017 Jul 11.
The mechanism of the HBr-catalyzed Friedel-Crafts-type reaction between β-naphthol and HCHO was investigated by DFT to improve this reaction. The HBr-H O co-catalyzed the preferential pathway undergoes the concerted nucleophilic addition and hydrogen shift, stepwise followed by H O elimination and the CC bond formation. The origin of the high catalytic activity of HBr is ascribed to CH···Br and OH···Br interactions, which suggest that the active species is Br . Moreover, water molecules efficiently assist in improving the activity of Br . The computational results show that solvent polarity profoundly affects the activation barriers. To our delight, the activation barrier of the rate-determining step for the favored pathway in water is comparable (0.6 kcal/mol difference) with that in acetonitrile. The experimental observation further confirmed our results and demonstrated that the title reaction can be successfully achieved "on water." Therefore, we open a new efficient and green strategy for the synthesis of biphenol derivatives. © 2017 Wiley Periodicals, Inc.
为了改进β-萘酚与甲醛之间的HBr催化的傅克型反应，采用密度泛函理论（DFT）研究了其反应机理。HBr-H₂O共催化的优先反应途径经历协同亲核加成和氢转移，随后依次进行H₂O消除和CC键形成。HBr高催化活性的起源归因于CH···Br和OH···Br相互作用，这表明活性物种是Br⁻。此外，水分子有效地协助提高了Br⁻的活性。计算结果表明，溶剂极性对活化能垒有深远影响。令人高兴的是，在水中有利途径的速率决定步骤的活化能垒与在乙腈中的活化能垒相当（相差0.6 kcal/mol）。实验观察进一步证实了我们的结果，并表明该反应可以在“水相”中成功实现。因此，我们为联苯酚衍生物的合成开辟了一种新的高效绿色策略。© 2017威利期刊公司
