A Three‐Enzyme System Involving an Ene‐Reductase for Generating Valuable Chiral Building Blocks

Abstract

The use of ene-reductase (ERED) enzymes for the asymmetric reduction of olefins offers a green, renewable alternative to metal-catalysed asymmetric reduction. We report herein the first example of an ERED-catalysed enantiospecific reduction carried out at large scale using a carbonyl reductase (CRED) enzyme in the cofactor recycle. This reaction has been paired with a hydrolase-mediated regioselective ester hydrolysis to generate a valuable chiral building block using a straightforward one-pot process.

Chemoenzymatic Asymmetric Synthesis of Pregabalin Precursors via Asymmetric Bioreduction of β-Cyanoacrylate Esters Using Ene-Reductases

“…In conclusion, this study demonstrates the applicability of ene-reductases as a general synthetic tool by meeting the demand for green and highly stereoselective synthetic methods. 31 …”

Ene‐reductases and their Applications

“…This multienzyme process includes the ER-catalyzed reduction of an α,β-unsaturated diester (22a) and subsequent hydrolysis of 22b by a hydrolase to the monoester (22c). Cofactor recycling was performed with an NAD(P) + /carbonyl reductase (CRED) including simultaneous coproduct (acetone) removal ( Figure 18.5c) [53].…”

“…Moreover product yield and/or enantioselectivity can vary dramatically, depending on the recycling system which has been employed [26,31,55]. Recent examples of cofactor recycling systems include the solventstable ADH from Rhodococcus ruber (ADH-A) [56] which uses only two equivalents of 2-propanol as H-donor or the selectAZyme CRED [53] that needs isopropanol as cosubstrate, both producing acetone. However, in the case of ADH-A, α,β-unsaturated aldehydes are not suitable substrates as the carbonyl function gets "overreduced" to the alcohol moiety [56].…”

New Generation of Biocatalysts for Organic Synthesis

“…Scientists at Almac developed a process for the production of monoacid building blocks in a threeenzyme one-pot process (Scheme 9). [38] A 98 % conversion of 70 g of substrate 36 was obtained after 48 h by using 70 g of ene reductase ERED-04 cell paste (from the SelectAZyme EESK-1300 screening kit). The product (R)-37 was then hydrolyzed with 25 g of hydrolase AH-33 under concomitant control of the pH value to afford 57 g of the desired monoacid (R)-38 (99 % ee) after 22 h. The NADH cofactor was regenerated by using a coupled-enzyme approach in which 2-propanol is oxidized to acetone by a solvent-stable carbonyl reductase (A131 from the SelectAZyme CRED enzyme kit).…”