Development of a Biocatalytic Process to Prepare (S)-N-Boc-3-hydroxypiperidine

Development of an enzymatic cascade to systematically utilize lignocellulosic monosaccharide

BACKGROUND

The fermentation valorization of two main lignocellulosic monosaccharides, glucose and xylose, is extensively developed; however, it is restricted by limited yield and process complexity. An in vitro enzymatic cascade reaction can be an alternative approach.

RESULTS

In this study, a three-stage, five-enzyme cascade was developed to convert pretreated biomass to valuable chemicals. First, a ribose-5-phosphate isomerase B mutant isomerized xylose to d-xylulose with high substrate specificity, and a d-arabinose dehydrogenase continued to reduce d-xylulose to d-arabitol. Simultaneously, glucose was utilized for the coenzyme regeneration catalyzed by a glucose dehydrogenase, generating useful gluconic acid and achieving 73% of total conversion rate after 36 h. Then, six kinds of pretreated biomass lignocellulose were hydrolyzed by cellulase and hemicellulase, and corn cob was identified as the initial substrate for providing the highest monosaccharide content. A 65% conversion rate of the lignocellulosic xylose was obtained after 24 h.

CONCLUSIONS

This study presents a proof of concept to convert main lignocellulosic monosaccharides systematically by an enzymatic cascade at stoichiometric ratio. © 2022 Society of Chemical Industry.

Efficient Synthesis of cis-4-Propylcyclohexanol Using a Mutant Alcohol Dehydrogenase Coupled with Glucose Dehydrogenase

cis-4-Propylcyclohexanol is an important intermediate for synthesizing trans-2-(4-propylcyclohexyl)-1,3-propanediol, which is widely used in the manufacture of liquid crystal displays. In this study, cis-4-propylcyclohexanol was prepared using a mutant alcohol dehydrogenase from Lactobacillus kefir (LK-TADH, A94T/F147L/L199H/A202L) coupled with glucose dehydrogenase. Using the optimal catalytic conditions, 125 g/L (250 g) of 4-propylcyclohexanone was completely transformed after 5 h, and 225.8 g of cis-4-propylcyclohexanol (cis/trans ratio of 99.5:0.5) was obtained through extraction and rotary evaporation at a yield of 90.32%. This study reports a potential method for the green production of cis-4-propylcyclohexanol as the key intermediate of trans-2-(4-propylcyclohexyl)-1,3-propanediol at an industrial level.

Efficient Asymmetric Synthesis of (S)-N-Boc-3-Hydroxypiperidine by Coexpressing Ketoreductase and Glucose Dehydrogenase

(S)-N-Boc-3-hydroxypiperidine is an important intermediate of the anticancer drug ibrutinib and is mainly synthesized by the asymmetric reduction catalyzed by ketoreductase coupled with glucose dehydrogenase at present. In this study, the coexpression recombinant strains E. coli/pET28-K-rbs-G with single promoter and E. coli/pETDuet-K-G with double promoters were first constructed for the coexpression of ketoreductase and glucose dehydrogenase in the same cell. Then, the catalytic efficiency of E. coli/pET28-K-rbs-G for synthesizing (S)-N-Boc-3-hydroxypiperidine was found to be higher than that of E. coli/pETDuet-K-G due to the more balanced activity ratio and higher catalytic activity. On this basis, the catalytic conditions of E. coli/pET28-K-rbs-G were further optimized, and finally both the conversion of the reaction and the optical purity of the product were higher than 99%. In the end, the cell-free extract was proved to be a better catalyst than the whole cell with the improved catalytic efficiency of different recombinant strains. This study developed a better coexpression strategy for ketoreductase and glucose dehydrogenase by investigating the effect of activity ratios and forms of the biocatalysts on the catalytic efficiency deeply, which provided a research basis for the efficient synthesis of chiral compounds.

Shortening Synthetic Routes to Small Molecule Active Pharmaceutical Ingredients Employing Biocatalytic Methods

Biocatalysis, using enzymes for organic synthesis, has emerged as powerful tool for the synthesis of active pharmaceutical ingredients (APIs). The first industrial biocatalytic processes launched in the first half of the last century exploited whole-cell microorganisms where the specific enzyme at work was not known. In the meantime, novel molecular biology methods, such as efficient gene sequencing and synthesis, triggered breakthroughs in directed evolution for the rapid development of process-stable enzymes with broad substrate scope and good selectivities tailored for specific substrates. To date, enzymes are employed to enable shorter, more efficient, and more sustainable alternative routes toward (established) small molecule APIs, and are additionally used to perform standard reactions in API synthesis more efficiently. Herein, large-scale synthetic routes containing biocatalytic key steps toward >130 APIs of approved drugs and drug candidates are compared with the corresponding chemical protocols (if available) regarding the steps, reaction conditions, and scale. The review is structured according to the functional group formed in the reaction.

Biocatalytic Reduction Reactions from a Chemist's Perspective

Reductions play a key role in organic synthesis, producing chiral products with new functionalities. Enzymes can catalyse such reactions with exquisite stereo-, regio- and chemoselectivity, leading the way to alternative shorter classical synthetic routes towards not only high-added-value compounds but also bulk chemicals. In this review we describe the synthetic state-of-the-art and potential of enzymes that catalyse reductions, ranging from carbonyl, enone and aromatic reductions to reductive aminations.

Biosynthesis of chiral cyclic and heterocyclic alcohols via CO/C–H/C–O asymmetric reactions

This review covers the recent progress in various biological approaches applied to the synthesis of enantiomerically pure cyclic and heterocyclic alcohols through CO/C–H/C–O asymmetric reactions.

Efficient synthesis of Ibrutinib chiral intermediate in high space-time yield by recombinant E. coli co-expressing alcohol dehydrogenase and glucose dehydrogenase

The production of (S)-N-boc-3-hydroxy piperidine (NBHP) via asymmetric bioreduction of 1-boc-3-piperidinone with reductase is impeded by the need for expensive coenzymes NAD(P)H. In order to regenerate the coenzyme in situ, the gene of alcohol dehydrogenase from Thermoanaerobacter brockii and glucose dehydrogenase from Bacillus subtilis were ligated into the multiple cloning sites of pRSFDuet-1 plasmid to construct the recombinant Escherichia BL21 (DE3) that co-expressing alcohol dehydrogenase and glucose dehydrogenase. Different culture conditions including the medium composition, inducer and pH etc were systematically investigated to improve the enzyme production. The enzyme activity was increased more than 11-fold under optimal culture condition, from 12.7 to 139.8 U L⁻¹. In the further work, the asymmetric reduction of 1-boc-3-piperidinone by whole cells of recombinant E. coli was systematic optimized to increase the substrate concentration and reaction efficiency. At last, S-NBHP (>99% ee) was prepared at 500 mM substrate concentration without external addition of cofactors. The conversion of S-NBHP reached 96.2% within merely 3 h, corresponding a high space-time yield around 774 g L⁻¹ d⁻¹. All these results demonstrated the potential of recombinant E. coli BL21 (DE3) coupled expressing alcohol dehydrogenase and glucose dehydrogenase for efficient synthesis of S-NBHP.

A simple and efficient process for the synthesis of optically active (S)-N-boc-3-hydroxy piperidine was developed using the “designer cells” co-expressing alcohol dehydrogenase and glucose dehydrogenase.

Characterization of a Carbonyl Reductase from Rhodococcus erythropolis WZ010 and Its Variant Y54F for Asymmetric Synthesis of (S)-N-Boc-3-Hydroxypiperidine

The recombinant carbonyl reductase from Rhodococcus erythropolis WZ010 (ReCR) demonstrated strict (S)-stereoselectivity and catalyzed the irreversible reduction of N-Boc-3-piperidone (NBPO) to (S)-N-Boc-3-hydroxypiperidine [(S)-NBHP], a key chiral intermediate in the synthesis of ibrutinib. The NAD(H)-specific enzyme was active within broad ranges of pH and temperature and had remarkable activity in the presence of higher concentration of organic solvents. The amino acid residue at position 54 was critical for the activity and the substitution of Tyr54 to Phe significantly enhanced the catalytic efficiency of ReCR. The k_cat/K_m values of ReCR Y54F for NBPO, (R/S)-2-octanol, and 2-propanol were 49.17 s⁻¹ mM⁻¹, 56.56 s⁻¹ mM⁻¹, and 20.69 s⁻¹ mM⁻¹, respectively. In addition, the (S)-NBHP yield was as high as 95.92% when whole cells of E. coli overexpressing ReCR variant Y54F catalyzed the asymmetric reduction of 1.5 M NBPO for 12 h in the aqueous/(R/S)-2-octanol biphasic system, demonstrating the great potential of ReCR variant Y54F for practical applications.

Asymmetric Reduction of Prochiral Ketones by Using Self-Sufficient Heterogeneous Biocatalysts Based on NADPH-Dependent Ketoreductases

The development of cell-free and self-sufficient biocatalytic systems represents an emerging approach to address more complex synthetic schemes under nonphysiological conditions. Herein, we report the development of a self-sufficient heterogeneous biocatalyst for the synthesis of chiral alcohols without the need to add an exogenous cofactor. In this work, an NADPH-dependent ketoreductase was primarily stabilized and further co-immobilized with NADPH to catalyze asymmetric reductions without the addition of an exogenous cofactor. As a result, the immobilized cofactor is accessible, and thus, it is recycled inside the porous structure without diffusing out into the bulk, as demonstrated by single-particle in operando studies. This self-sufficient heterogeneous biocatalyst was used and recycled for the asymmetric reduction of eleven carbonyl compounds in a batch reactor without the addition of exogenous NADPH to achieve the corresponding alcohols in 100 % yield and >99 % ee; this high performance was maintained over five consecutive reaction cycles. Likewise, the self-sufficient heterogeneous biocatalyst was integrated into a plug flow reactor for the continuous synthesis of one model secondary alcohol, which gave rise to a space-time yield of 97-112 g L^-1  day^-1 ; additionally, the immobilized cofactor accumulated a total turnover number of 1076 for 120 h. This is one of the few examples of the successful implementation of continuous reactions in aqueous media catalyzed by cell-free and immobilized systems that integrate both enzymes and cofactors into the solid phase.

A Biocatalytic Route to Highly Enantioenriched β-Hydroxydioxinones

A novel biocatalytic system to access a wide variety of β-hydroxydioxinones from β-ketodioxinones employing commercial engineered ketoreductases has been developed. This practical system provides a remarkably straightforward solution to limitations in accessing certain chemical scaffolds common in β-hydroxydioxinones that are of great interest due to their diversification capabilities. A few highlights of this system are that it is high yielding, highly enantioselective, and chromatography-free. We have demonstrated both a wide substrate scope and a high degree of scalability.