通过DFT方法研究了手性磷酸催化苯乙酮与吲哚之间二芳基化反应的详细机理,并将其与2,2,2-三氟苯乙酮与吲哚之间的反应机理进行了比较。计算结果证实了我们先前的假设,即酮中的CF 3基团在活化底物和稳定叔醇的单一芳基化产物中起着完美的双重作用。还证明了甲基酮的CH 3基团中的F取代比例不同(CH 3− n F n,n= 0、1、2、3)对拟议的二芳基化过程的键脱水步骤的活化能有不同的影响,并确定后续的重芳基化是继续进行还是被抑制。通过我们在80°C下进行的其他实验已验证了在较高的反应温度下可以克服二芳基化反应的决定速率脱水步骤中CF 3和CHF 2酮的阻障性的计算预测。此外,已经用两层ONIOM方法研究了手性磷酸催化的三氟甲基酮的单芳基化的高对映选择性。实验观察到的对映异构体过量可以成功地合理化。
Asymmetric Arylation of 2,2,2-Trifluoroacetophenones Catalyzed by Chiral Electrostatically-Enhanced Phosphoric Acids
作者:Jie Ma、Steven R. Kass
DOI:10.1021/acs.orglett.8b00900
日期:2018.5.4
A series of highly reactive metal-free chiralphosphoricacids possessing positively charged phosphonium ion substituents are reported and have been applied to Friedel–Crafts alkylations of indoles and 2,2,2-trifluoromethyl aryl ketones. These catalysts are orders-of-magnitude more active and have similar or better enantioselectivities than their noncharged analogues. High tolerance to a range of substrates
Trifluoromethanesulfonic acid-catalyzed solvent-free bisindolylation of trifluoromethyl ketones
作者:Yi Wang、Yu Yuan、Chun-Hui Xing、Long Lu
DOI:10.1016/j.tetlet.2013.12.078
日期:2014.1
A trifluoromethanesulfonic acid-catalyzed solvent-free bisindolylation reaction of indoles with alkyl and aryl trifluoromethyl ketones has been developed. The trifluoromethyl-substituted bisindolylalkane derivatives were synthesized in moderate to excellent yields. (C) 2014 Elsevier Ltd. All rights reserved.