Cascade Coupling of Ene‐Reductases and ω‐Transaminases for the Stereoselective Synthesis of Diastereomerically Enriched Amines

Abstract

One‐pot sequential and cascade processes performed by employing ene‐reductases (ERs) together with ω‐transaminases (ω‐TAs) for the obtainment of diastereomerically enriched (R)‐ and (S)‐amine derivatives containing an additional stereocenter were investigated. By using either α‐ or β‐substituted unsaturated ketones as substrates and by coupling purified ERs belonging to the Old Yellow Enzyme (OYE) family with a panel of commercially available ω‐TAs, the desired products were obtained in up to >99 % conversion and >99 % de. The sequential reactions were performed in a one‐pot fashion with no need to adapt the reaction conditions to the reductive amination step or to purify the reaction intermediate. Moreover, high chemoselectivity of the tested ω‐TAs for the saturated ketones was shown in the cascade reactions.

Use of Immobilized Amine Transaminase from Vibrio fluvialis under Flow Conditions for the Synthesis of (S)‐1‐(5‐Fluoropyrimidin‐2‐yl)‐ethanamine

“…In this case, the ( S )‐amine formation catalyzed by Vf ‐ATA relies exclusively on the PLP intrinsically bound to Vf ‐ATA. We concluded, indeed, that the driving force of the side‐reaction was the concentration of PLP used in the reactions (1‐2 mM) which is probably uselessly high for the biotransformation, although consistent with other reports on transaminases . Furthermore, the hypothesized mechanism might be enhanced by the alkaline pH of the reaction mixture: at this pH value (around 8–9), ATAs show the highest activity, but amines are predominant in their neutral form.…”

“…We concluded, indeed, that the driving force of the side-reaction was the concentration of PLP used in the reactions (1-2 mM) which is probably uselessly high for the biotransformation, although consistent with other reports on transaminases. [55][56][57][58] Furthermore, the hypothesized mechanism might be enhanced by the alkaline pH of the reaction mixture: at this pH value (around 8-9), ATAs show the highest activity, but amines are predominant in their neutral form. Thus, the nucleophilic reaction of amines with the PLP aldehyde group is plausible to occur.…”

Development of Biotransamination Reactions towards the 3,4-Dihydro-2H-1,5-benzoxathiepin-3-amine Enantiomers

“…In this context, the synthesis of chiral amines is particularly challenging, with the conversion of prochiral ketones into optically active amines receiving great attention in recent years [11][12][13][14] by using mainly imine reductases [15][16][17] and amine transaminases (ATAs) [18][19][20][21][22][23]. Taking into account the potential of ATAs in the single biotransamination of cyclic ketones [24][25][26][27][28][29][30][31][32], even as part of multienzymatic sequences [33][34][35][36][37][38], but especially since they have served as valuable biocatalysts in the production of pharmacologically active products [39][40][41][42][43], we have focused herein our efforts in the pursuit of an efficient biotransamination protocol for 3,4-dihydro-2H-1,5-benzoxathiepin-3-one (6).…”

Covalent Linkage of an R‐ω‐Transaminase to a d‐Amino Acid Oxidase through Protein Splicing to Enhance Enzymatic Catalysis of Transamination

“…Chiral amines are important chemicals for the synthesis of pharmaceuticals . ω‐Transaminases (ω‐TAs) are multimeric enzymes and have been investigated for their utility in the preparation of chiral amines .…”