Diastereomeric control of enantioselectivity: evidence for metal cluster catalysis

Abstract

Enantioselective hydrogenation of tiglic acid effected by diastereomers of the general formula [(μ-H)2Ru3(μ3-S)(CO)7(μ-P–P*)] (P–P* = chiral Walphos diphosphine ligand) strongly supports catalysis by intact Ru3 clusters.

Homogeneous Catalysis by Organometallic Polynuclear Clusters

“…Furthermore, Singh and Nordlander investigated the effect of a face-capping chalcogenide to provide stability of the cluster framework in a triruthenium cluster under hydrogenation of 29a [87]. Thus, employing the Walphos-ligand affords two diastereomers of the Ru3-cluster 34, Scheme 11a.…”

“…Catalytic scheme for the asymmetric hydrogenation of 29a to 30a as proposed by Nordlander. Terminal CO molecules have been omitted for clarity, [87].…”

Asymmetric hydrogenation of an α-unsaturated carboxylic acid catalyzed by intact chiral transition metal carbonyl clusters – diastereomeric control of enantioselectivity

“…Molecular structures of [(µ-H) 2 Ru 3 (µ 3 -S)(CO) 7 (µ-1,2-1a)] 3 and 4 25 and [(µ-H) 2 Ru 3 (µ 3 -S)(CO) 7 (µ-1,2-1b)] 5 and 6. The molecular structures of 3-6 are shown in Fig.…”

Polyhedral Flexibility in the Sulfido-Capped Cluster H2Ru3(CO)9(μ3-S) on Reaction with 2-(Diphenylphosphino)thioanisole (PS) and Reversible Tripodal Rotation of the Chelated PS Ligand in H2Ru3(CO)7(κ2-PS)(μ3-S)

“…We recently published a report on the catalytic hydrogenation of tiglic acid using the diphosphine-substituted clusters H 2 Ru 3 (CO) 7 (Walphos)­(μ 3 -S) [where Walphos = chiral 2′-(diphenylphosphino)­phenyl]­ferrocenyl}­ethyldi­[3,5-bis­(trifluoromethyl)­phenyl]­phosphine] . The H 2 Ru 3 (CO) 7 (Walphos)­(μ 3 -S) cluster exists as a pair of Walphos-bridged diastereomers where the phosphine ligand bridges one of the hydride-bridged Ru–Ru bonds through the axial and equatorial sites.…”