Transfer hydrogenation of aryl ketones with homogeneous ruthenium catalysts containing diazafluorene ligands

Abstract

Novel cationic ruthenium(II) complexes bearing a 4,5‐diazafluorene unit and p‐cymene as ligands have been synthesised. The complexes were characterised based on elemental analysis and Fourier transform infrared and nuclear magnetic resonance spectroscopies. The synthesised Ru(II) complexes were employed as pre‐catalysts for the transfer hydrogenation of aromatic ketones using 2‐propanol as both hydrogen source and solvent in the presence of NaOH. All complexes showed high catalytic activity as catalysts in the reduction of substituted acetophenones to corresponding secondary alcohols. The products of catalysis were obtained with conversion rates of between 80 and 99%. Among the seven new complexes investigated, the most efficient catalyst showed turnover frequencies in the range 255–291 h−1 corresponding to 85 to 97% conversion, respectively. Copyright © 2016 John Wiley & Sons, Ltd.

4,5-Diazafluorene and 9,9’-Dimethyl-4,5-Diazafluorene as Ligands Supporting Redox-Active Mn and Ru Complexes

“…In their work, Song and co-workers have found that the acidic C-H bonds of daf can undergo deprotonation that results in follow-up reactivity [16][17][18][19][20]. More broadly, Stahl [21][22][23] and several other groups [24][25][26] have developed a number of catalyst systems supported by diazafluorene ligands. In all these cases, daf and its derivatives seem to play a decisive role in enabling unique chemistry, confirming the usefulness of the ligands as a counterpoint to the more common R bpy family.…”

Efficient emission of Zn(ii) and Cd(ii) complexes with nopinane-annelated 4,5-diazafluorene and 4,5-diazafluoren-9-one ligands: how slight structural modification alters fluorescence mechanism

“…4,5-Diazafluorene ( daf ) and 4,5-diazafluoren-9-one ( dafo , Scheme 1) can be considered as analogues of bipy , as they contain the 2,2-bipyridine fragment that makes them suitable for N , N -chelating coordination. 15–35 However, the pyridyl groups in daf and dafo are additionally tied together by a –CH 2 – or a CO group, respectively. This leads to larger distances between the donor atoms than that of bipy and, therefore, enforces larger bite angles.…”

“…The potential of these ligands for coordination chemistry was recognized much later than for bipy , and therefore, metal complexes with daf and dafo derivatives have been explored to a much lesser extent. 15–35…”