All for one: A combination of three biocatalysts (ω-transaminase, alanine dehydrogenase, and an enzyme such as formate dehydrogenase cofactor recycling) catalyze a cascade to achieve the asymmetric transformation ketone into primary α-chiral unprotected amine through formal stereoselective reductive amination (see scheme). Only ammonia reducing agent (formate) are consumed during this reaction.

Abstract Various ω‐transaminases were tested for the synthesis of enantiomerically pure amines from corresponding ketones employing D ‐ or L ‐alanine as amino donor and lactate dehydrogenase to remove side‐product pyruvate shift unfavourable reaction equilibrium product side. Both enantiomers, ( R )‐ S )‐amines, could be prepared with up 99% ee >99% conversions within 24 h at 50 mM substrate concentration. The activity stereoselectivity amination depended on ω‐transaminase employed;...

Abstract The stereoinversion of one enantiomer into its mirror‐image counterpart within a racemate furnishes single stereoisomeric product in 100 % theoretical yield. This extremely efficient type deracemization, whereby substrate and possess an identical chemical structure, can be achieved by using bio‐ or chemo‐catalysts combinations thereof is applicable to secondary alcohols, amines α‐substituted carboxylic acids. Special emphasis devoted the background one‐pot, single‐step...

A series of synthetic nicotinamide cofactors were synthesized to replace natural and promote enoate reductase (ER) catalyzed reactions without compromising the activity or stereoselectivity bioreduction process. Conversions enantioselectivities >99% obtained for C═C bioreductions, process was successfully upscaled. Furthermore, high chemoselectivity observed when employing these cofactor mimics (mNADs) with crude extracts in ER-catalyzed reactions.

Quasi-irreversible oxidation of sec-alcohols was achieved via biocatalytic hydrogen transfer reactions using alcohol dehydrogenases employing selected ketones as acceptors, which can only be reduced but not oxidized. Thus, 1 equiv oxidant required instead a large excess. For the both isomers methylcarbinols single nonstereoselective short-chain dehydrogenase/reductase from Sphingobium yanoikuyae identified and overexpressed in E. coli.

Mono- and biphasic aqueous−organic solvent systems (50% v v-1) as well micro-aqueous organic (99% were successfully employed for the biocatalytic reduction of ketones catalyzed by alcohol dehydrogenase ADH-A from Rhodococcus ruber via hydrogen transfer. A clear correlation between log P enzyme activitythe higher, betterwas found. The use solvents allowed highly stereoselective enzymatic carbonyl reductions at substrate concentrations close to 2.0 M.

Ketones with two bulky substituents, named bulky-bulky ketones, as well less sterically demanding ketones were successfully reduced to the corresponding optically highly enriched alcohols using a novel identified recombinant short-chain alcohol dehydrogenase RasADH from Ralstonia sp. DSM 6428 overexpressed in E. coli.

Critical parameters affecting the stereoselective amination of (hetero)aromatic ketones using transaminases have been studied, such as temperature, pH, substrate concentration, cosolvent, and source percentage amino donor, to further optimize production enantiopure amines both (S)- (R)-selective biocatalysts from commercial suppliers. Interesting building blocks obtained, overcoming some limitations traditional chemical synthetic methods. Representative processes were scaled up, affording...

Abstract An efficient catalytic system to oxidize quantitatively aliphatic diols using Trametes versicolor laccase and TEMPO has been developed in aqueous medium. Oxidations have occurred a non‐stereoselective fashion but with complete regio‐ and/or monoselectivity, obtaining lactones excellent purity after simple extraction. This demonstrated be scalable, compatible the presence of variety functionalities, also allowed successful enzyme recycling laccase‐cross‐linked aggregates (CLEA) preparation.

A one-pot/two-step chemoenzymatic sequential methodology has been developed for the selective amination of secondary alcohols by combining laccase from <italic>Trametes versicolor</italic>/TEMPO catalytic system with stereoselective action transaminases.

A concurrent cascade combining the use of a gold(I) N-heterocyclic carbene (NHC) and an alcohol dehydrogenase (ADH) is disclosed for synthesis highly valuable enantiopure halohydrins in aqueous medium under mild reaction conditions. The methodology consists gold-catalyzed regioselective hydration easily accessible haloalkynes, followed by stereoselective bioreduction corresponding α-halomethyl ketone intermediates. Thus, series alkyl- aryl-substituted haloalkynes have been selectively...

Employing the over-expressed highly organic solvent tolerant alcohol dehydrogenase ADH-'A' from Rhodococcus ruber DSM 44541, versatile building blocks, which were not accessible by wild type catalyst, obtained in > 99% e.e.; furthermore, employing d8-2-propanol as deuterium source, stereoselective biocatalytic transfer was made feasible to furnish enantiopure labeled sec-alcohols on a preparative scale single enzyme.

Alle für einen: Eine Kombination von drei Biokatalysatoren (ω-Transaminase, Alanin-Dehydrogenase und ein Enzym wie Formiat-Dehydrogenase die Zurückgewinnung des Cofaktors) katalysiert eine Reaktionskaskade zur Umwandlung eines Ketons in primäres α-chirales ungeschütztes Amin durch formale stereoselektive reduktive Aminierung (siehe Schema). Nur Ammoniak das Reduktionsmittel (Formiat) werden dieser Reaktion verbraucht.

The use of purified and overexpressed alcohol dehydrogenases to synthesize enantiopure fluorinated alcohols is shown. When the bioreductions were performed with ADH-A from Rhodococcus ruber in E. coli, no external cofactor was necessary obtain (R)-derivatives. Employing Lactobacillus brevis ADH, it possible achieve synthesis (S)-fluorohydrins at a 0.5 M substrate concentration. Furthermore, due activated character these substrates, huge excess hydrogen donor not necessary.

Nowadays, the design of sustainable processes applicable at industrial scale is highly desirable due to environmental reasons. The use biocatalytic reactions carry out oxidative transformations one possible strategies framed in here mildness and usually high selectivities achieved with these methods. Anyway, while implementing this type system several drawbacks must be overcome order obtain efficient setups. Historically, main issues has been cofactor-dependency biocatalysts active. Herein,...

Lactobacillus brevis ADH (LBADH) is an alcohol dehydrogenase that commonly employed to reduce alkyl or aryl ketones usually bearing a methyl, ethyl chloromethyl as small ketone substituent the corresponding (R)-alcohols. Herein we have tested series of 24 acetophenone derivatives differing in their size and electronic properties for reduction employing LBADH. After plotting relative activity against measured substrate volumes observed apart from other effects must be responsible obtained....

Abstract Deep‐eutectic solvents (DES) are cost‐effective, nonhazardous that may be used in biocatalysis as nonconventional media enable biotransformations with industrially sound high substrate loadings. Based on promising prognoses, this paper explores successfully the use of whole cells overexpressing oxidoreductases biocatalysts for stereoselective reduction ketones different DES–aqueous‐media solutions. Enzymes like Ralstonia sp. alcohol dehydrogenase (ADH) and horse liver ADH,...

A series of enantiopure hydroxy esters and lactones has been synthesized in a chemodivergent manner via alcohol dehydrogenase (ADH) reduction the corresponding keto by means cascade or tandem protocols. Thus, ADH from Rhodococcus ruber (ADH-A) Lactobacillus brevis (LBADH) afforded both antipodes very selective way when dealing with small derivatives. With bulkier substrates, Ralstonia sp. (RasADH) was successfully employed to achieve synthesis enantioenriched γ- δ-hydroxy esters. To isolate...

An efficient methodology to oxidize β,β-dihalogenated secondary alcohols employing oxygen was achieved in a biphasic medium using the laccase from Trametes versicolor/TEMPO pair, providing corresponding ketones clean fashion under very mild conditions. Moreover, chemoenzymatic protocol has been applied successfully deracemize 2,2-dichloro-1-phenylethanol combining this oxidation with an alcohol dehydrogenase-catalyzed bioreduction.

Abstract Both cis ‐ and trans ‐but‐2‐ene‐1,4‐diamines have been prepared efficiently applied as sacrificial cosubstrates in enzymatic transamination reactions. The best results were obtained with the ‐diamine. thermodynamic equilibrium of stereoselective process is shifted to amine formation due tautomerization 5 H ‐pyrrole into 1 ‐pyrrole, achieving high conversions (78–99%) enantiomeric excess (up &gt;99%) by using a small donor. Furthermore, when reaction proceeded, strong coloration was...

A natural deep eutectic solvent composed by choline chloride and glucose has been used as both cosolvent cofactor regenerating system for alcohol dehydrogenase-catalysed bioreductions.