Development of a Practical Biocatalytic Process for (R)-2-Methylpentanol

Abstract

(R)-2-Methylpentanol is an important chiral intermediate for the synthesis of certain medicinally important compounds, natural products, and liquid crystals. Here we describe the development of a practical kinetic resolution utilizing an enantiospecific biocatalytic reduction of racemic 2-methylvaleraldehyde. The process utilizes an evolved ketoreductase enzyme to selectively reduce the (R)-enantiomer of racemic 2-methylvaleraldehyde to the desired product with high volumetric productivity. A scaleable method for separating the desired product from the off-enantiomer of the starting material is also described. The process is cost-effective, green, and amenable to manufacturing scale.

Identification of ketone reductase ChKRED20 from the genome of Chryseobacterium sp. CA49 for highly efficient anti-Prelog reduction of 3,5-bis(trifluoromethyl)acetophenone

“…ChKRED20 was well expressed in E. coli and represented over 60% of the total soluble protein (Fig. 5); therefore, lyophilized powder of crude enzyme was applied as the catalyst according to recent successful industrial applications of ketone reductases [7][8][9]. Product (R)-1b was achieved with excellent enantioselectivity (>99.9% ee) and conversion (>99%) in 24 h (Table 3, entry 1).…”

“…Requirements [2] Table S4) [7][8][9][10][11][12]. In addition, ChKRED20 could use 2-propanol as a cheap co-substrate for cofactor regeneration, and the crude enzyme could easily tolerate 40% (v/v) of 2-propanol in the reaction system.…”

“…In the last decade, successful application of ketone reductases (KRED) either as whole-cells or isolated enzymes has risen rapidly. In particular, several processes using isolated/crude recombinant enzymes coupled with efficient recycling systems have been developed into industrial-scale production with excellent stereoselectivity and economic advantage [7][8][9][10][11][12]. The use of recombinant enzymes greatly facilitates the scale-up with high volumetric productivity and the absence of side reactions [2,13,14].…”

Bioreductive production of enantiopure (S)-duloxetine intermediates catalyzed with ketoreductase ChKRED15

“…The bioreduction serves as a powerful approach for the production of optically active alcohols, which are widely used as fundamental intermediates for pharmaceuticals, agrochemicals and other products with chiral centers [1][2][3][4][5][6]. With the increased availability of recombinant ketoreductases, industrial-scale processes using cell-free enzymes coupled with efficient recycling systems have been developed rapidly in the past decade, which provides high volumetric productivity, excellent stereoselectivity, absence of side reactions and other economic advantages [7][8][9][10][11][12].…”

Rapid asymmetric reduction of ethyl 4-chloro-3-oxobutanoate using a thermostabilized mutant of ketoreductase ChKRED20

“…In addition, when significant improvement of catalytic properties is demanded, the recombinant enzymes can always be engineered via directed evolution to meet the process requirements. Hence, the application spectrum of the KREDs has been greatly expanded (Gooding et al 2010;Huisman et al 2010;Kosjek et al 2008;Liang et al 2010;Ma et al 2010;Solano et al 2012).…”