Chemoenzymatic Dynamic Kinetic Resolution of Alcohols and Amines

Lee, Jin Hee; Han, Kiwon; Kim, Mahn‐Joo; Park, Jaiwook

doi:10.1002/ejoc.200900935

Cited by 226 publications

(74 citation statements)

References 118 publications

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“…Therefore, the catalyst needs to differentiate two enantiomers of racemic alkynyl esters in a highly stereoselective manner for the kinetic resolution. Furthermore, if the same catalyst promotes the racemization of both enantiomers, the dynamic kinetic resolution (DKR) [38][39][40] of the racemic alkynes would be realized to provide chiral trisubstituted allenoesters in good yield without recovering the other enantiomers, which are less reactive in the 1,3-proton migration (Scheme 5). Several bifunctional catalysts 1-3 were screened for the isomerization of alkyne 15a.…”

Section: Isomerization Of α-Substituted 3-butynoates Via Dynamic Kinementioning

confidence: 99%

Bifunctional Guanidines as Hydrogen-Bond-Donating Catalysts

Kobayashi

Takemoto

2015

Topics in Heterocyclic Chemistry

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Bicyclic guanidines, bearing 2-aminoquinazolin-4-one and 3-aminobenzothiadiazine-1,1-dioxide core structures, work as bifunctional amine catalysts, due to a double hydrogen-bond-donating ability of two guanidine N-H protons, which are capable of activating both nucleophile and electrophile simultaneously. In fact, these guanidine catalysts revealed to promote several asymmetric reactions such as hydrazination of active methylene compounds with azodicarboxylate and 1,3-proton migration of alkynoates to allenoates as well as the oxa-Michael addition and epoxidation of α,β-unsaturated amides and esters with better chemical yields and higher enantioselectivities than the corresponding thioureas. The catalytic mechanisms of these asymmetric reactions and their synthetic applications for biologically active molecules are also discussed in this chapter.

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Section: Isomerization Of α-Substituted 3-butynoates Via Dynamic Kinementioning

confidence: 99%

Bifunctional Guanidines as Hydrogen-Bond-Donating Catalysts

Kobayashi

Takemoto

2015

Topics in Heterocyclic Chemistry

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“…[14] Due to the intrinsic selectivities shown by enzymes when reacting with racemic mixtures, the combination of biocatalyzed methodologies with different racemization techniques has allowed the efficient development of enzymatic-based DKRs. [15][16][17][18][19] Among the different features that a good DKR process must accomplish, probably the most important is that the racemization reaction should be fast enough in order to maintain a perfect equilibration between both enantiomers in the racemic mixture. It must be taken into account that an inefficient rate would afford an increasing concentration of the non-reacting enantiomer and therefore, a loss in the selectivity within the time.…”

Section: Dynamic Kinetic Resolutions (Dkrs)mentioning

confidence: 99%

Why Leave a Job Half Done? Recent Progress in Enzymatic Deracemizations

Díaz‐Rodríguez¹,

Lavandera

Gotor³

2015

CGC

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Abstract. In recent years the usefulness of enzymatic systems to obtain a single stereoisomerically pure compound starting from a racemate has been expanded. Moreover, current advances in protein engineering, molecular biology and modeling tools are the basis to improve the catalytic properties of enzymes to face novel synthetic challenges. Also, medium engineering and novel immobilization methods of (bio)catalysts are enhancing the productivity of biocatalytic processes making them suitable for being scalable. The development of multienzymatic protocols and the combination of enzymes with other catalysts are providing a wide range of synthetic possibilities that are expanding the scope of these transformations even at industrial scale. Herein we will describe an overview of recent (chemo)enzymatic deracemizations, focusing on the strategy employed (dynamic kinetic resolution, stereoinversion, cyclic deracemization or enantioconvergent process), the type of substrate (e.g., alcohols, amines, carboxylic acid derivatives or carbonylic compounds), and the biocatalyst(s) used.

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“…Metals such as rhodium, iridium and ruthenium are known to racemise secondary alcohols, for the in situ conversion of unwanted enantiomers to products, but only a few of these metals have proved compatible with enzymatic reaction conditions, and these have been reviewed. 250,[272][273][274][275][276][277][278][279][280][281] The first example of a chemoenzymatic DKR of secondary alcohols was reported by Williams; a ruthenium catalyst was combined with a lipase to produce enantiopure acetate of 1-phenyl ethanol in 81% conversion and 96% e.e. 278 Bäckvall made significant improvements to this procedure by using immobilised Candida antarctica Lipase B and a ruthenium complex.…”

Section: Dynamic Kinetic Resolution With Metal Catalystsmentioning

confidence: 99%

“…250,[272][273][274][275][276][277][278][279][280][281] It should be noted that vinyl acetate is incompatible with the ruthenium complexes explored, while isopropenyl acetate can be used with the majority of monomeric ruthenium complexes. p-Chlorophenyl acetate is the best acyl donor for the dimeric ruthenium complexes.…”

Section: Scheme 14mentioning

confidence: 99%

Recent trends in whole cell and isolated enzymes in enantioselective synthesis

Milner¹,

Maguire²

2012

Arkivoc

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Modern synthetic organic chemistry has experienced an enormous growth in biocatalytic methodologies; enzymatic transformations and whole cell bioconversions have become generally accepted synthetic tools for asymmetric synthesis. This review details an overview of the latest achievements in biocatalytic methodologies for the synthesis of enantiopure compounds with a particular focus on chemoenzymatic synthesis in non-aqueous media, immobilisation technology and dynamic kinetic resolution. Furthermore, recent advances in ketoreductase technology and their applications are also presented.Keywords: Biocatalysis, kinetic and dynamic kinetic resolution, Baker's yeast, ketoreductases General IntroductionAsymmetric synthesis is the preferential formation of one stereoisomer of a chiral target compound to another; when scientists at GlaxoSmithKline, AstraZeneca and Pfizer 1 examined 128 syntheses from their companies, they found as many as half of the drug compounds made by their process research and development groups are not only chiral but also contain an average of two chiral centres each. 2In 2006 just 25 % were derived from the chiral pool and over 50 % employed chiral technologies. 1In order to meet regulatory requirements enantiomeric purities of 99.5 % were deemed necessary by the FDA. 3 This is one of the biggest challenges which face chemists today, primarily due to the recognition of the fact that different enantiomers of the same compound can interact differently in biological systems. As a consequence, the production of single enantiomers instead of racemic mixtures has become an important process in the pharmaceutical and agrochemical industry. Several routes can lead to the desired enantiomer including transition metal-, [4][5][6] organo-5,7-10 and bio-catalysis [11][12][13][14][15] and these have been thoroughly reviewed in the literature. 16,17 2. Biocatalysis IntroductionBiocatalysis involves the use of enzymes or whole cells (containing the desired enzyme or enzyme system) as catalysts for chemical reactions. A timeline of historic events in biocatalysis and biotechnology is outlined in Table 1. [18][19][20] Reviews and Accounts Novel methodologies for discovering industrial enzymes based on genomic sequencing and phage display (discussed further in Section 1.3), 21,22 as well as highly effective optimisation tools based on chemical, physical and molecular biology approaches, 23 have improved the access to biocatalysts, increased their stability, and radically broadened their specificity. 24This greater availability of catalysts with superior qualities including the use of new bioengineering tools contributed significantly to the development of new industrial processes. Biocatalytic methodologies for organic synthesis were outlined by Woodley et al. in three categories: established, emerging and expanding chemistries as depicted in Figure 1. 25 Enzyme classesBy the late 1950s it had become evident that the nomenclature of enzymes without any guiding authority, in a period when the...

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Chemoenzymatic Dynamic Kinetic Resolution of Alcohols and Amines

Cited by 226 publications

References 118 publications

Bifunctional Guanidines as Hydrogen-Bond-Donating Catalysts

Bifunctional Guanidines as Hydrogen-Bond-Donating Catalysts

Why Leave a Job Half Done? Recent Progress in Enzymatic Deracemizations

Recent trends in whole cell and isolated enzymes in enantioselective synthesis

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