Dynamic kinetic resolution of phenylglycine esters via lipase-catalysed ammonolysis

Wegman, M. A.; Hacking, Michiel A. P. J.; Rops, J.; Pereira, Pedro C.; Rantwijk, Fred van; Sheldon, Roger A.

doi:10.1016/s0957-4166(99)00143-3

Cited by 74 publications

(36 citation statements)

References 15 publications

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“…On the basis of this fact, we propose the mechanism presented in Scheme 2 for the aldehyde-catalyzed racemization. [21,27] After condensation reaction of the amino acid ester with 3,5-dinitrosalicylaldehyde (11), the acidity of the α-hydrogen atom at the chiral center is remarkably increased. Hence, rapid protonation-deprotonation at the α-carbon atom takes place, which causes racemization.…”

Section: Racemization Of α-Amino Acidsmentioning

confidence: 99%

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Dynamic Kinetic Resolution of α‐Amino Acid Esters in the Presence of Aldehydes

Schichl¹,

Enthaler²,

Holla³

et al. 2008

Eur J Org Chem

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Section: Racemization Of α-Amino Acidsmentioning

confidence: 99%

“…[21] Careful adjustment of the reaction conditions gave (R)-phenylglycine amide in 88 % ee and 85 % conversion. To ensure high selectivity, the reaction was performed at low temperature (-20°C), which resulted in longer reaction times (66 h).…”

Section: Introductionmentioning

confidence: 99%

Dynamic Kinetic Resolution of α‐Amino Acid Esters in the Presence of Aldehydes

Schichl¹,

Enthaler²,

Holla³

et al. 2008

Eur J Org Chem

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“…A similar concept was applied to the DKR of phenyl glycine esters catalyzed by lipases in an aminolysis reaction [45] .…”

Section: The Enzymatic Kinetic Resolution Of Amino Acid Esters Couplementioning

confidence: 99%

Chemo‐Enzymatic Deracemization Methods

Tessaro¹,

Molla²,

Pollegioni³

et al. 2008

Modern Biocatalysis

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13 IntroductionIn recent times, the term deracemization has been used for describing techniques becoming increasingly important for the preparation of chiral compounds as single enantiomers. The term refers to a process in which one single enantiomer is obtained when starting from a racemate [1] .The two more common strategies for achieving such an objective are deracemization by stereoinversion or deracemization by dynamic kinetic resolution DKR (Scheme 13.1 ).Deracemization by stereoinversion is a process in which one form (S f ) of the racemic starting material (R f + S f ) is enantioselectively transformed into an intermediate (S i ) which can in turn react to give the form of opposite confi guration (R f ). An example of this method could be the selective oxidation of one enantiomer of a racemic secondary alcohol and the subsequent reduction with a catalyst of opposite stereopreference [2] .Deracemization by DKR is in principle a kinetic resolution process in which the non -transformed enantiomer is racemized in situ. The conditions are that a chiral catalyst promotes the transformation of one enantiomer (R s ) into the product (R p ) while the other enantiomer is racemized at a comparable rate and the racemic mixture (R s + S s ) is restored. The product (R p ) is not racemized under the same conditions. While a simple kinetic resolution yields a maximum of 50% of the product, with this technique a 100% conversion can be reached. Although the majority of chiral molecules of industrial interest are still prepared by kinetic resolution, the continuous development of industrial enzymes and racemizing processes fosters new chemo -or biocatalytic systems for DKR to appear. A great impulse for deracemization methods based on the one -pot/two -steps resolution racemization process was brought about by B ä ckvall et al . over a 10 -year period [3] .The method is of general applicability in the deracemization of secondary alcohols and amines and consists of a lipase -catalyzed irreversible acylation and in situ racemization of the non -reacted enantiomer catalyzed by a ruthenium catalyst,

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“…The bacterium utilizes D-alanine (DAla) for synthesis of the peptidoglycan cell wall. The cofactor PLP is found in a wide range of different enzymes catalyzing a vast variety of reactions, and the uses for such enzymes in organic synthesis could be plentiful (Chen et al, 1994;Hacking et al, 1998;Steinreiber et al, 2007;Wegman et al, 1999). Since this enzyme is thermostable, the purification method described by Inagaki et al (1986) involves heat treatment after expression in Escherichia coli.…”

Section: Introductionmentioning

confidence: 99%

Silica‐immobilized His₆‐tagged enzyme: Alanine racemase in hydrophobic solvent

Cassimjee

Trummer

Branneby

et al. 2007

Biotech & Bioengineering

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A new immobilization method for enzymes is presented to facilitate synthetic applications in aqueous as well as organic media. The enzyme Alanine racemase (AlaR) from Geobacillus stearothermophilus was cloned, overexpressed and then immobilized on a silica-coated thin-layer chromatography plate to create an enzyme surface. The enzyme, fused to a His(6)-tag at its N-terminal, was tethered to the chemically modified silica-coated TLC plate through cobalt ions. The immobilized enzyme showed unaltered kinetic parameters in small-scale stirred reactions and retained its activity after rinsing, drying, freezing or immersion in n-hexane. This practical method is a first step towards a general immobilization method for synthesis applications with any enzyme suitable for His6-tagging.

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Dynamic kinetic resolution of phenylglycine esters via lipase-catalysed ammonolysis

Cited by 74 publications

References 15 publications

Dynamic Kinetic Resolution of α‐Amino Acid Esters in the Presence of Aldehydes

Dynamic Kinetic Resolution of α‐Amino Acid Esters in the Presence of Aldehydes

Chemo‐Enzymatic Deracemization Methods

Silica‐immobilized His₆‐tagged enzyme: Alanine racemase in hydrophobic solvent

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Dynamic kinetic resolution of phenylglycine esters via lipase-catalysed ammonolysis

Cited by 74 publications

References 15 publications

Dynamic Kinetic Resolution of α‐Amino Acid Esters in the Presence of Aldehydes

Dynamic Kinetic Resolution of α‐Amino Acid Esters in the Presence of Aldehydes

Chemo‐Enzymatic Deracemization Methods

Silica‐immobilized His6‐tagged enzyme: Alanine racemase in hydrophobic solvent

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Product

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Silica‐immobilized His₆‐tagged enzyme: Alanine racemase in hydrophobic solvent