Scale‐up and intensification of (S)‐1‐(2‐chlorophenyl)ethanol bioproduction: Economic evaluation of whole cell‐catalyzed reduction of o‐Chloroacetophenone

Abstract

Escherichia coli cells co-expressing genes coding for Candida tenuis xylose reductase and Candida boidinii formate dehydrogenase were used for the bioreduction of o-chloroacetophenone with in situ coenzyme recycling. The product, (S)-1-(2-chlorophenyl)ethanol, is a key chiral intermediate in the synthesis of polo-like kinase 1 inhibitors, a new class of chemotherapeutic drugs. Production of the alcohol in multi-gram scale requires intensification and scale-up of the biocatalyst production, biotransformation, and downstream processing. Cell cultivation in a 6.9-L bioreactor led to a more than tenfold increase in cell concentration compared to shaken flask cultivation. The resultant cells were used in conversions of 300 mM substrate to (S)-1-(2-chlorophenyl)ethanol (e.e. >99.9%) in high yield (96%). Results obtained in a reaction volume of 500 mL were identical to biotransformations carried out in 1 mL (analytical) and 15 mL (preparative) scale. Optimization of product isolation based on hexane extraction yielded 86% isolated product. Biotransformation and extraction were accomplished in a stirred tank reactor equipped with pH and temperature control. The developed process lowered production costs by 80% and enabled (S)-1-(2-chlorophenyl)ethanol production within previously defined economic boundaries. A simple and efficient way to synthesize (S)-1-(2-chlorophenyl)ethanol in an isolated amount of 20 g product per reaction batch was demonstrated.

Asymmetric Transfer Hydrogenation of Ketones Using New Iron(II) (P‐NH‐N‐P′) Catalysts: Changing the Steric and Electronic Properties at Phosphorus P′

“…The reduction of K4 and K5 with chloro substituents on the phenyl ring is achieved with high conversions, with the ortho ‐chloro substituent in K5 producing much higher ee (84‐94 % depending on the catalyst) than with the para ‐chloro group in K4 (6‐58 % ee). High enantiopurity is beneficial for the production of ( R )‐2′‐chloro‐1‐phenylethanol as it is a key intermediate for a chemotherapeutic drug . The bis ‐CF 3 ‐substituted arylketone K6 is fully reduced to the alcohol in >90 % ee by C1 and ( S,S )‐2 that contain PAr 2 groups while ( S,S )‐1 with a more basic PEt 2 group appears to be deactivated by the acidic alcohol product after 40–60 % conversion.…”

Integrated process design for biocatalytic synthesis by a Leloir Glycosyltransferase: UDP‐glucose production with sucrose synthase

“…The vector provides ampicillin resistance and target protein expression under the control of a constitutive promoter (P34) (Aerts et al, ). LB medium supplemented with 20 g/L glucose · H 2 O, 1 g/L NH 4 Cl; 0.25 g/L MgSO 4 · 7H 2 O; 3 g/L K 2 HPO 4 , 6 g/L KH 2 PO 4 , 0.1 mL/L polypropylene glycol, 115 μg/mL ampicillin, 2 μg/mL thiamine, and trace elements was used (medium C2, Eixelsberger et al, ). Pre‐cultures (300 mL in 1000 mL baffled shake flasks) were inoculated from glycerol stock.…”

“…The efficiency of the whole‐cell catalyst production is critical to the performance of the biocatalytic process (Eixelsberger et al, ; Tufvesson et al, ). As earlier reported in Diricks et al (), SuSyAc was expressed in Escherichia coli harboring the expression vector pCXP34h, in which the SuSyAc gene was under the control of a constitutive promoter of intermediate strength (Fig.…”

“…This results in a specific whole cell activity of ∼450 U/g CDW as a target value. To achieve this, we replaced E. coli shake flask cultivation previously used for production of SuSyAc (Diricks et al, ), by a batch fermentation process using LB medium supplemented with glucose, trace elements, and additional salts (medium C2; see the Supporting Information; Eixelsberger et al, ). Full time‐courses of glucose utilization, biomass growth, and SuSyAc activity were recorded and the results are shown in Figure A.…”

Unsymmetrical Iron P‐NH‐P′ Catalysts for the Asymmetric Pressure Hydrogenation of Aryl Ketones

“…The o ‐chloro‐substituted ketone (entry 3) is considered a challenging substrate for asymmetric reduction but it is efficiently and selectively reduced by this catalyst system. The product ( S )‐1‐(2‐chlorophenyl)ethanol has been identified as a key chiral intermediate in the synthesis of a new class of chemotherapeutic drugs . Cyclohexyl phenyl ketone (entry 4) proved to be a difficult substrate to reduce, with less than 40 % conversion and low ee .…”