18153-40-7Relevant articles and documents
Lewis acid-catalyzed tandem synthesis of 9-sulfonylamino- and 9-arylfluorenes
Huang, Dayun,Yang, Weiguang,Zhang, Jianlan,Wang, Xuesong,Wang, Xinyan,Hu, Yuefei
, p. 47570 - 47578 (2016/06/06)
A Lewis acid-catalyzed three-step tandem synthesis of 9-arylfluorene was developed by simply heating a mixture of 2-formyl biphenyl, TsNCO and an arene. In the absence of arene, a two-step tandem synthesis of 9-sulfonylaminofluorene was achieved. These ad
TfOH catalyzed synthesis of 9-arylfluorenes via tandem reaction under warm and efficient conditions
Li, Qingcui,Xu, Wengang,Hu, Jiaxing,Chen, Xiaoqing,Zhang, Fanglin,Zheng, Hua
, p. 27722 - 27725 (2014/07/21)
A tandem ring-closing reaction was developed for the synthesis of 9-arylfluorenes and their derivatives. The reaction is metal-free, straightforward and efficient under warm conditions. More than 99% yield is obtained. This journal is the Partner Organisations 2014.
Flash photolysis study of a Friedel-Crafts alkylation. Reaction of the photogenerated 9-fluorenyl cation with aromatic compounds
McClelland, Robert A.,Cozens, Frances L.,Li, Jianhui,Steenken, Steen
, p. 1531 - 1544 (2007/10/03)
A combination of flash photolysis and product analysis is employed to investigate the reaction of aromatic compounds (ArH) with the 9-fluorenyl cation (Fl+) photogenerated from 9-fluorenol in 1,1,1,3,3,3-hexafluoroisopropyl alcohol (HFIP).The availability of the photochemical route to Fl+ means that the reaction of benzylic-type cation with ArH can be directly followed by flash photolysis.An additional feature with electron-rich ArH is that the cyclohexadienyl cation is observed to grow as Fl+ decays.Thus both cationic intermediates of a Friedel-Crafts alkylation are observed in the same experiment.The formation of the cyclohexadienyl cation is demonstrated to be reversible, or at least quasi-reversible, with the kinetic analysis furnishing absolute rate constants for the formation of this cation as well as for its loss of H+ and Fl+.Values of kH:kD for benzene:benzene and toluene:toluene are ca. 1.5 and demonstrate that Fl+ addition is at least partly reversible with these compounds as well.The Hammett ρ+ value obtained for a series of the less electron-rich ArH is -8, indicative of a transition state with considerable cyclohexadienyl cation character.Anisole shows a negative deviation from from Hammett correlation line, explained by the addition of Fl+ to ArH becoming encounter-controlled.This behaviour is dramatically illustrated in a comparison of data for Fl+ and Br2.For the less electron-rich ArH, rate constants for the two electrophiles are parallel.However, from m-xylene through pentamethylbenzene, the rate with Fl+ is unchanged, while the rate with Br2 increases over 1000-fold.The concept of encounter control with Fl+ is strongly supported by the absolute rate constants, which for the electron-rich ArH are all in the range 1-2 E9 dm3 mol-1 s-1, a magnitude typical of diffusion-controlled reactions.The electron-rich ArH also show no intermolecular selectivity since their reactions are encounter-controlled, but have a high intramolecular selectivity.It is suggested that a factor influencing the latter is the reversibility of formation of the cyclohexadienyl cation from the encounter complex.