Jeffamine® ED‐600: a polyether amine donor for enzymatic transamination in organic solvent/solvent‐free medium with membrane‐assisted product extraction

Abstract

BACKGROUND: Amine transaminases have been extensively used for synthesizing various pharmaceutically relevant compounds, mainly in aqueous media. However, their applications are often limited by poor substrate solubility, low productivity and difficult product separation. This paper reports the use of Jeffamine ® ED-600, a novel polyether amine donor, for the transaminase-catalyzed synthesis of 4-phenyl-2-butylamine in non-aqueous media.RESULTS: Enzymatic transamination was performed in the presence of a non-polar organic solvent (n-heptane), in which the selected amine donor is not soluble, thus a two-liquid-phase system was achieved. Coupling the reaction system with membrane-assisted extraction resulted in simultaneous recovery of product, without any consistent contamination of the unreacted substrates. Moreover, a product yield of 60% was reached, compared with 15% without product extraction. The reaction was also successfully conducted without addition of any organic solvent, thus providing the first example of a solvent-free transamination system. In the presence of only enzyme and substrates, up to 6-fold higher product concentrations were achieved compared with the reaction performed in organic solvent. CONCLUSION: The use of the Jeffamine ® ED-600 in non-aqueous media resulted beneficial for 4-phenyl-2-butylamine synthesis. Enzymatic transamination in organic solvent with membrane-assisted product extraction enabled shifting of the equilibrium and selective product extraction. Solvent-free transamination minimized the required volume of the reactor and minimized the environmental impact. Extension to other substrate/enzyme solvent-free systems could open new possibilities and perspectives in transaminase-catalyzed chiral amine synthesis. Two-liquid-phase transaminationTransamination was performed in 10 mL glass vials (diameter 2.5 cm), in which a biphasic system was built (Fig. 1, left side). According to our previous studies, 16 0.05 g of TA-v2 enzyme was wetted with 100 μL of 0.5 mmol L −1 PLP/water mixture. The amine donor (AD) Jeffamine ED-600 was then added to the vials (either J Chem Technol Biotechnol 2020; 95: 604-613

Three‐liquid‐phase Spinning Reactor for the Transaminase‐catalyzed Synthesis and Recovery of a Chiral Amine

“…Besides the use of an excess of amine donor (AD), methods such as co‐product or product cyclization or polymerization, evaporation of the volatile co‐product and enzymatic cascades for co‐product removal have been developed. Membrane‐assisted techniques for in situ product removal have been also investigated . Specifically, membrane‐based three liquid phase (3LP) systems were developed by filling the pores of an hydrophobic hollow fibre membrane contactor with an hydrophobic solvent.…”

“…We have previously demonstrated the feasibility of performing the asymmetric synthesis of ( S )‐1‐methyl‐3‐phenylpropylamine using high molecular weight (HMW) donor amines in aqueous, organic solvent and solvent‐free media . With a molecular weight (MW) between 400 and 1500 g/mol, these large molecules were effectively retained by commercial nanofiltration membranes, when employed in an aqueous environment .…”

“…Transamination using HMW ADs was also performed in the presence of a non‐polar organic solvent ( n ‐heptane). Specifically, the HMW AD Jeffamine ED‐600 (MW of 600 g/mol), commercialized by Huntsman corporation, was insoluble in n‐heptane, thus, resulting in a two‐liquid‐phase system . Coupling the two‐liquid phase reaction system with membrane‐assisted product extraction, the reaction equilibrium was successfully shifted to reach 60 % conversion compared to 15 % without product extraction.…”

“…Based on the previous studies, n ‐heptane was selected as organic solvent phase A . The substrate 4‐phenyl‐2‐butanone (BA), initially supplied to phase A , progressively moved to phase C .…”

“…The first transaminase‐mediated synthesis combined with continuous product recovery was performed employing the same configuration of the preliminary partitioning experiment (Figure , configuration 1). Having already proven in our recent work the reproducibility of the reaction system, a single experiment at 1L scale was carried out. Out of 5 g of ketone substrate, initially added in n ‐heptane, only 0.8 g of MPPA was extracted and isolated after 17 days operation (Figure ).…”