An iron variant of the Noyori hydrogenation catalyst for the asymmetric transfer hydrogenation of ketones

Abstract

A new type of iron catalyst that structurally mimics the Noyori hydrogenation catalyst can catalyze the asymmetric transfer hydrogenation of ketones.

Transfer Hydrogenation of Aldehydes and Ketones in Air with Methanol and Ethanol by an Air-Stable Ruthenium–Triazole Complex

“…Although Meerwein–Ponndorf–Verley reduction has been widely utilized in both academic and industrial processes, the major drawbacks of this protocol are the requirement of a large amount of aluminum alkoxide reagent, unwanted side reactions, and moisture sensitivity of aluminum alkoxides. Over the last few decades, transfer hydrogenation of multiple bonds between carbon and heteroatoms (such as oxygen and nitrogen in carbonyls and imines, respectively) is a very active field of research and a large variety of homogeneous transition metal catalysts based on iron, − ruthenium, − osmium, − cobalt, − rhodium, − iridium, − nickel, − palladium, − and gold , have been developed. However, most of the efficient transfer hydrogenation protocols utilized ruthenium-, rhodium-, or iridium-based catalysts.…”

Air-Stable Coordinatively Unsaturated Ruthenium(II) Complex for Ligand Binding and Catalytic Transfer Hydrogenation of Ketones from Ethanol

“…The use of EtOH as hydrogen source complements the more commonly employed isopropanol and formic acid − and offers major benefits, as it is widely available, environmentally friendly, and a very low-cost hydrogen source. The major reason for the scarce utilization of primary alcohols as hydrogen sources is their unfavorable redox potential.…”

(Primary Amido)-ene(amido) Ni(II) Catalysts Containing a P-Chirogenic Substituted Ferrocene Moiety for Highly Enantioselective Asymmetric Transfer Hydrogenation of Ketones

“…Following Chen’s synthetic strategy, , we introduce P-chirogenic substituents diastereoselectively into the ferrocene backbone. Following the previous strategy of our group, we introduce the aldehyde group without racemization and cleavage of the P-chirogenic phosphino group.…”

“…of 95%. To explain the reasons why catalyst 2n generated the ( S )-configuration products with relatively high enantioselectivities, we analyzed the interaction energies of the substrate and intermediate 3n in the transition state with Multiwfn software, using the EDA-FF method based on the molecular force field (Figure b). ,, The analytical results showed that the ( S )-configuration of the phosphine kept the ( S )-planar chiral ferrocene group far from the reacting site in the TS S ‑ACP transition state. This provided enough space for the aryl ring of the substrate and the ene­(amido) moiety of the catalyst to approach each other, resulting in the formation of a strong π–π interaction.…”

“…Chiral ferrocene moieties exhibit high chemical stabilities and a broad range of applications in asymmetric synthetic reactions. − The design of chiral ligands on the backbone of ferrocene allows for precise tuning of the asymmetric environment, resulting in high enantioselectivity. ,,,− To better tune the asymmetric environments of the nickel catalysts, we decided to introduce a planar chiral ferrocene moiety into the ligands of the nickel catalysts. The rationale for the catalyst design is similar to that of our previously reported iron catalysts that contained binaphthyl skeletons; a bifunctional ATH catalyst requires an amino ligand to cooperate with the NiH center in 2-propanol activation and carbonyl group hydrogenation. Furthermore, based on our previous findings on the activation of 3d metals, the catalyst structure must contain an ene(amido) moiety .…”