Enantioselective epoxidation of unfunctionalized alkenes by a chiral monooxoruthenium(IV) complex [RuL(bpy)O]²⁺{L = 2,6-bis[(4S,7R)-7,8,8-trimethyl-4,5,6,7-tetrahydro-4,7-methanoindazol-2-yl]pyridine; bpy = 2,2′-bipyridine}

Abstract

A new chiral monooxoruthenium(iv) complex containing 2,6-bis 8,5,6,pyridine and 2,2'-bipyridine ligands is prepared and the X-ray crystal structure of its Ru"--OH2 precusor determined; this RuiV=O complex catalyses epoxidation of unfunctionalized alkenes with prom isi ng ena nt i oselectivity.

Ruthenium-Catalyzed Reactions for Organic Synthesis

“…The use of oxoruthenium complexes bearing optically active nitrogen ligands such as 88 provides enantioselective catalytic epoxidation of unfunctionalized olefins (eq 152) . Catalytic asymmetric epoxidation of styrene has been performed using a combination of chiral ruthenium porphyrin catalyst 89 with 2,6-dichloropyridine N -oxide to afford styrene oxide in 57% ee …”

Hydrocarbon Oxidation Catalyzed by [Ru(TDL)(XY)Z] Complexes (TDL = Tridentate Ligand; XY = Bidentate Ligand and Z = H2O or Halide)

“…Additional support in favor of the above argument comes from the linear Hammett plot constructed by plotting the relative reactivity (k rel = k pss /k s ; where k pss and k s represent secondorder rate constants for the oxidation of para-substituted styrene and styrene, respectively) against the TE values (total substituent effect parameter) [23]. In the context of asymmetric epoxidation, rutheniumoxo complexes containing chiral ligands 'cbpy' and 'PPz*' that afford enantioselective epoxidation of unfunctionalized olefins was first reported by Che and co-workers [17,19,26]. The results of stoichiometric oxidation of styrene by [Ru IV (cbpy)(Me 3 tacn))O] resulted in only 9% ee [17].…”

Chiral Emissive Lanthanide Complexes from Enantiopure [6]Helicene‐bis(pyrazolyl)‐pyridine Ligands

“…[12] In the frame of our own interest in functional helicenes, [13,14] and their transition metal complexes, [9,15] we have recently reported the series of 2,6bis(pyrazol-1-yl)pyridine (1-bpp) ligands substituted by racemic [4]-, [5]-and [6]helicene units in the 4-position of the pyridine ring, together with the photophysical properties of their luminescent Re(I) and Ru(II) complexes. [16] While a large variety of functionalized 1-bpp and corresponding transition metal complexes have been reported, [17,18] chiral derivatives have received little attention so far, [19,20] especially driven by catalytic applications, [21,22] but not for emission or chiroptical properties.…”