Dynamic Kinetic Resolution of Benzoins by Lipase−Metal Combo Catalysis

Hoyos, Pilar; Fernández, María José Frutos; Sinisterra, J. V.; Alcántara, Andrés R.

doi:10.1021/jo061060b

Cited by 67 publications

(49 citation statements)

References 53 publications

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“…An efficient DKR protocol for benzoins (1,2-diaryl-2-hydroxyethanones) was presented by Alcántara and coworkers in 2006 using Shvo's catalyst 1 for the racemization [78]. For the enzymatic resolution, Pseudomonas stutzeri lipase (Lipase TL) was used, giving the (S)-acylated products in excellent enantiomeric excesses (>99% ee) and with yields up to 90% (16).…”

Section: Dkr Of Secondary Alcoholsmentioning

confidence: 99%

Shvo’s Catalyst in Hydrogen Transfer Reactions

Warner

Casey

Bäckvall

2011

Bifunctional Molecular Catalysis

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This chapter reviews the use of Shvo's catalyst in various hydrogen transfer reactions and also discusses the mechanism of the hydrogen transfer. The Shvo catalyst is very mild to use since no activation by base is required in the transfer hydrogenation of ketones or imines or in the transfer dehydrogenation of alcohols and amines. The Shvo catalyst has also been used as an efficient racemization catalyst for alcohols and amines. Many applications of the racemization reaction are found in the combination with enzymatic resolution leading to a dynamic kinetic resolution (DKR). In these dynamic resolutions, the yield based on the starting material can theoretically reach 100%. The mechanism of the hydrogen transfer from the Shvo catalyst to ketones (aldehydes) and imines as well as the dehydrogenation of alcohols and amines has been studied in detail over the past decade. It has been found that for ketones (aldehydes) and alcohols, there is a concerted transfer of the two hydrogens involved, whereas for typical amines and imines, there is a stepwise transfer of the two hydrogens. One important question is whether the substrate is coordinated to the metal or not in the hydrogen transfer step(s). The pathway involving coordination to activate the substrate is called the inner-sphere mechanism, whereas transfer of hydrogen without coordination is called the outer-sphere mechanism. These mechanistic proposals together with experimental and theoretical studies are discussed.

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Section: Dkr Of Secondary Alcoholsmentioning

confidence: 99%

Shvo’s Catalyst in Hydrogen Transfer Reactions

Warner

Casey

Bäckvall

2011

Bifunctional Molecular Catalysis

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“…Table 3 shows the excellent results obtained in the DKR of 1,2-diarylethanols [28] and benzoins. [36] Chemoenzymatic DKR is possible not only for simple aliphatic alcohols but also for those containing additional functional groups, such as alkenols, ethers, chlorohydrins, azido alcohols, amino alcohols, hydroxy esters, hydroxy phosphates, hydroxy sulfonates, and hydroxy amides (Table 4). In some cases, more than two functional groups were compatible with the conditions for DKR.…”

Section: Substrate Alcohols In Chemoenzymatic Dkrmentioning

confidence: 99%

Chemoenzymatic Dynamic Kinetic Resolution of Alcohols and Amines

et al. 2010

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Dynamic kinetic resolution (DKR) is an attractive process for the transformation of racemic mixtures into optically active compounds. For successful DKR, efficient racemization is required while the kinetic resolution is proceeding. This Microreview mainly summarizes the recent developments in the DKR of alcohols and amines, based on metal-catalyzed racemization and enzymatic acylation in a single reaction vessel.

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“…Nevertheless, a systematic study on lipase-promoted transacylation (five different wild-type lipases were screened) concluded that Pseudomonas aeruginosa lipase is active and R selective toward bulky phenylalkanols. [6] Pseudomonas stutzeri lipase-catalyzed dynamic kinetic resolution (DKR) of 1,2-diarylethanols [7] and benzoins [8][9] (1,2-diaryl-2-hydroxyethanone structures) have been recently reported. In addition, substrates that have very bulky side groups flanking the carbonyl, such as phenyl isopropyl ketone, tend to be poor substrates for most known alcohol dehydrogenases.…”

Section: Introductionmentioning

confidence: 99%

Mutant Lipase‐Catalyzed Kinetic Resolution of Bulky Phenyl Alkyl sec‐Alcohols: A Thermodynamic Analysis of Enantioselectivity

2010

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The size of the stereoselectivity pocket of Candida antarctica lipase B limits the range of alcohols that can be resolved with this enzyme. These steric constrains have been changed by increasing the size of the pocket by the mutation W104A. The mutated enzyme has good activity and enantioselectivity toward bulky secondary alcohols, such as 1-phenylalkanols, with alkyl chains up to eight carbon atoms. The S enantiomer was preferred in contrast to the wild-type enzyme, which has R selectivity. The magnitude of the enantioselectivity changes in an interesting way with the chain length of the alkyl moiety. It is governed by interplay between entropic and enthalpic contributions and substrates with long alkyl chains are resolved best with E values higher than 100. The enantioselectivity increases with temperature for the small substrates, but decreases for the long ones.

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Dynamic Kinetic Resolution of Benzoins by Lipase−Metal Combo Catalysis

Cited by 67 publications

References 53 publications

Shvo’s Catalyst in Hydrogen Transfer Reactions

Shvo’s Catalyst in Hydrogen Transfer Reactions

Chemoenzymatic Dynamic Kinetic Resolution of Alcohols and Amines

Mutant Lipase‐Catalyzed Kinetic Resolution of Bulky Phenyl Alkyl sec‐Alcohols: A Thermodynamic Analysis of Enantioselectivity

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