Ligand with perfluorinated groups

Only a few years after the development of the homogeneous chiral Mn(salen) complexes by Jacobsen and Katsuki, several research groups began to study different immobiUzation methods in both liquid and soUd phases. Fluorinated organic solvents were the first type of Uquid supports studied for this purpose. The main problem in the appUcation of this methodology is the low solubility of the catalytic complex in the fluorous phase. Several papers were pubUshed by Pozzi and coworkers, who prepared a variety of salen ligands with perfluorinated chains in positions 3 and 5 of the saUcyUdene moiety (Fig. 2). 

Ligands with polar functional groups and fluori-nated phases are shown in Figure 7. Pentafluorophe-nyl packings and perfluorinated alkyl packings are utilized in reversed-phase chromatography. Cyano and nitrophenyl packings are useful both in normal-phase and in reversed-phase HPLC. The primary use... 

The limitations of the system with regard to substrates and oxidants was attributed to the strong electron-withdrawing character of the perfluorinated chains and the lower steric hindrance in the position adjacent to phenols, in marked contrast to the ferf-butyl groups present in Jacobsen s catalyst, hi view of this, a second generation of fluorinated salen ligands le and If was... 

Utilizing i2, or coordination modes of 2,3,5,6-tetrafluoro-l,4-benzenedicarboxylic acid (tfbda), several partially or fully perfluorinated MOFs have been synthesized with or without addition of co-ligands. Various groups reported a large number of perfluorinated... 

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