Sodium Chloride → Ethyl (3S)-4-chloro-3-hydroxybutanoate

Participants

Reaction Steps

To a well-stirred solution of 100 mM potassium phosphate buffer, 500 mM NaCl, pH 7 (1 L) at room temperature was added glucose (160 g, 830 mmoles, 1.1 equiv). To this was added ketoreductase SEQ ID NO: 2 (0.9 g), glucose dehydrogenase-S06 SEQ ID NO: 10 (0.5 g) and NADP (0.5 g) as lyophilized powders. Once dissolved, butyl acetate (500 mL) was added to form an emulsion. To this emulsion was added a solution of ethyl 4-chloroacetoacetate (10 g, 608 mmoles) in butyl acetate (500 mL), dropwise over 3 hours. The pH was maintained between 6.8 and 7 by an automatic titrater that dispensed Na2CO3 (2M in water, about 160 mL total). After 40 hours the automated addition of the base had ceased and there was no residual starting material by gas chromatography. The layers were separated, and the aqueous phase was washed with ethyl acetate (500 mL). The combined organics were dried over anhydrous sodium sulfate, filtered and evaporated on a rotary evaporator, to give essentially pure (˜97%) ethyl (S)-4-chloro-3-hydroxybutyrate.

Provenance & Evidence