Asymmetric hydrogenation of exocyclic γ,δ-unsaturated β-ketoesters to functionalized chiral allylic alcohols via dynamic kinetic resolution

Abstract

An iridium catalyzed asymmetric hydrogenation of racemic exocyclic γ,δ-unsaturated β-ketoesters via dynamic kinetic resolution to functionalized chiral allylic alcohols was developed. With chiral spiro iridium catalysts Ir-SpiroPAP a series of...

Thermodynamics of the elementary steps of organic hydride chemistry determined in acetonitrile and their applications

“…Similar to alkenes and imines, aldehydes and ketones play a very important role in organic chemistry and organic synthesis. 103,104 The reduction of aldehydes and ketones (K) generally involves the hydride mechanism, such as Meerwein–Ponndorf reduction, 105 NaBH 4 reduction, hydrogen-atom mechanism, such as H 2 reduction, 103,104 and electron mechanism, such as Na/C 2 H 5 OH reduction, from reducers to K. In the literatures, many researches were limited to computing the hydride affinity of a few aldehydes and ketones (K) in the gas phase due to the unavailability of hydride. 106,107 Given that the deeper theoretical thermodynamic research on aldehydes and ketones needs high-quality experimental data of common aldehydes and ketones, in previous work, the thermodynamic data of alkenes 42 and imines 41 were determined by accepting hydride in acetonitrile, subsequently overcoming the challenges of determining the hydride affinities for a much wider range of K (Scheme 33).…”

Biocatalytic asymmetric synthesis of secondary allylic alcohols using Burkholderia cepacia lipase immobilized on multiwalled carbon nanotubes

“…Chemical stereoselective methods are available for the synthesis of pure enantiomers of allylic alcohols, including reduction of prochiral ketones 8,12 and hydrogenation of enones 13 . However, these methods are not particularly practical due to the use of high temperatures and pressure and argon atmosphere; moreover, the catalytic process involves a metal ligand 5,12,13 …”

“…11 Chemical stereoselective methods are available for the synthesis of pure enantiomers of allylic alcohols, including reduction of prochiral ketones 8,12 and hydrogenation of enones. 13 However, these methods are not particularly practical due to the use of high temperatures and pressure and argon atmosphere; moreover, the catalytic process involves a metal ligand. 5,12,13 Thus, a relevant way to achieve the synthesis of optically active allylic alcohol is enzymatic kinetic resolution (EKR) using lipases (EC 3.1.1.3), which can be carried out through the acylation of a secondary allylic alcohol.…”

“…13 However, these methods are not particularly practical due to the use of high temperatures and pressure and argon atmosphere; moreover, the catalytic process involves a metal ligand. 5,12,13 Thus, a relevant way to achieve the synthesis of optically active allylic alcohol is enzymatic kinetic resolution (EKR) using lipases (EC 3.1.1.3), which can be carried out through the acylation of a secondary allylic alcohol. 2,3,11,14,15 In addition to lipases, oxidoreductases have also been successfully applied to obtain these chiral compounds through deracemization of the corresponding racemic mixtures, combining nonselective chemoenzymatic oxidation and a stereoselective biocatalyzed reduction.…”

Iridium-catalyzed chemoselective asymmetric hydrogenation of conjugated enones with ferrocene-based multidentate phosphine ligands

“…In the 1990s, Noyori and co-workers reported their pioneer work in chemoselective asymmetric hydrogenation of alkenyl alkyl ketones, and promising results were obtained by using RuCl 2 (xylbinap)(1,2-diamine) as a catalyst. 5 a Since then, Zhou, Huang, Zhang, Ikrial and others have reported several catalytic systems and achieved high enantioselective 1,2-reduction of alkenyl alkyl ketones with molecular hydrogen (Scheme 1a), 7 which greatly promoted the development of asymmetric hydrogenation of conjugated enones. Nevertheless, these catalytic systems just fit for the reduction of alkenyl alkyl ketones, and only moderate enantioselectivity was obtained in asymmetric 1,2-reduction of alkenyl aryl ketones.…”