研究了一系列9-芴基阳离子,结果表明,杂环取代基上电荷的增加可增强碳正离子系统的抗芳烃特性。类似地,已经研究了一系列二苯并亚戊烯基阳离子,并且显示出增加取代基上的电荷可增强碳正离子体系中的芳香特性。这些研究包括使用稳定离子条件和低温NMR对双阳离子和三阳离子物种的直接观察。使用DFT计算进一步表征了这些离子的结构,证实了高电荷有机离子可能在4 n或4 n +2π系统中表现出不寻常的π电子分布和电子离域。
Synthesis of Heterocycle-Containing 9,9-Diarylfluorenes Using Superelectrophiles
作者:Makafui Gasonoo、Akinari Sumita、Kenneth N. Boblak、Kristen Giuffre、Tomohiko Ohwada、Douglas A Klumpp
DOI:10.1021/acs.joc.7b00311
日期:2017.6.16
method for the synthesis of 9,9-diarylfluorenes is described. The chemistry involves cyclizations and arylations with biphenyl-substituted heterocyclic ketones and a mechanism is proposed involving superelectrophilic intermediates. The key reactive intermediates–dicationic and trication fluorenyl cations have been observed by low-temperature NMR and the mechanism has been further studied using DFT calculations
Functionalized fluorenes via dicationic electrophiles
作者:Michael R. Stentzel、Douglas A. Klumpp
DOI:10.1016/j.tetlet.2019.05.046
日期:2019.6
Dicationic fluorenylcations are shown to react with nitriles to provide amide-functionalized fluorenes. A similar reaction with alcohols gives ether derivatives. The chemistry is initiated by the reactions of N-heterocyclic ketones in a superacidic solution. This leads to cyclizations involving 2-biphenyl groups and formation of the reactive fluorenylcations.
Efficient rhodium(I)-catalyzed regioselective direct arylation and alkenylation of aromatic C−H bonds has been realized with aromatic carboxylic and cinnamic anhydrides as the coupling partners via decarbonylation and C−H activation under phosphine-free conditions.
Intramolecular Conjugate Additions with Heterocyclic Olefins
作者:Kenneth N. Boblak、Makafui Gasonoo、Yiliang Zhang、Douglas A. Klumpp
DOI:10.1021/acs.joc.5b01701
日期:2015.12.18
been studied. In triflic acid-promoted reactions, conjugate addition is observed with pyrazine-, 2-pyrimidine-, and 2-quinoxaline-based olefins and a phenyl group nucleophile. Markovnikov addition is observed with pyridine and 5-quinoxaline-based olefins. These results are in accordance with previous observations relating the type of addition—conjugate or Markovnikov—to the positions of olefinic substituents
Rhodium-Catalyzed Regioselective C−H Functionalization via Decarbonylation of Acid Chlorides and C−H Bond Activation under Phosphine-Free Conditions
作者:Xiaodan Zhao、Zhengkun Yu
DOI:10.1021/ja803154h
日期:2008.7.1
Efficient rhodium(I)-catalyzed regioselective functionalization of aromatic C-H bonds has been realized with acid chlorides as the coupling partners via decarbonylation and C-H activation under phosphine-free conditions.