Ruthenium(ii) N,S-heterocyclic carbene complexes and transfer hydrogenation of ketones

Abstract

A series of ruthenium(II) N,S-heterocyclic carbene (NSHC) complexes Ru(II)X(RCOO)(PPh(3))(2)(3-R'BzTh) (BzTh = benzothiazol-2-ylidene; R = Me, R'/X = Bz/Br (4), Pr(i)/I (6), Bu(i)/I (8); R = Et, R'/X = Bz/Br (5), Pr(i)/I (7), Bu(i)/I (9)) have been synthesized and characterized. Single-crystal X-ray structural analysis revealed that in each case the Ru(II) center adopts an essentially octahedral geometry, coordinated by two trans-oriented PPh(3) completed by an NSHC, chelating carboxylate and halide X (X = Br (4-5), X = I (6-9)) ligands. Although thiazol-2-ylidiene Ru(II) complexes are established and applied in metathesis, these benzothiazol-2-ylidene complexes (4-9) are the first of its kind. Their catalytic activities towards transfer hydrogenation of ketones have been examined and discussed.

Efficient transfer hydrogenation reaction Catalyzed by a dearomatized PN3P ruthenium pincer complex under base-free Conditions

“…These reactions are particularly convenient for larger-scale synthesis, since it avoids the employment of high hydrogen pressure and hazardous reducing agents. Selected recent examples include the well-defined pincer-type N-heterocyclic carbene ruthenium complexes [31], tetradentate iminophosphorane-based ruthenium complexes [32], heterocyclic carbene ruthenium complexes [33,34], and unsymmetrical NNN ruthenium complexes [35]. These results prompted us to investigate the reactivities of our new PN 3 P ruthenium complexes toward transfer hydrogenation ( Table 2).…”

The Golden Age of Transfer Hydrogenation

“…322 Its catalytic property toward TH of ketones was examined, showing that this kind of catalyst allowed TH with relatively low efficiency.…”

N-Propylphthalimide-Substituted Silver(I) N-Heterocyclic Carbene Complexes and Ruthenium(II) N-Heterocyclic Carbene Complexes: Synthesis and Transfer Hydrogenation of Ketones

“…In recent years a large number of applications dealing with this issue have been reported [36,37]. In this process, the reaction conditions, partially contain mild conditions, economic and environmentally friendly is very important.…”