Lipase catalyzed kinetic resolution for the production of (S)-3-[5-(4-fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-one: An intermediate for the synthesis of ezetimibe

Efficient enzymatic methods were developed for the synthesis of (S)-3-[5-(4-fluoro-phenyl)-5-hydroxy-pentanoyl]-4-phenyl-oxazolidin-2-one, by transesterification of (RS)-3-[5-(4-fluorophenyl)-5-hydroxypentanoyl]-4(S)-4-phenyl-1,3-oxazolidin-2-one [(R,S)-FOP alcohol] and hydrolysis of (RS)-1-(4-fluorophenyl)-5-oxo-5-[(S)-2-oxo-4-phenyloxazolidin-3-yl] pentyl acetate [(R,S)-FOP acetate] using lipase as enzyme source. The synthesized S-diastereomer is an intermediate for the potent cholesterol absorption inhibitor, ezetimibe. Among various lipases tried, Candida rugosa lipase in diisopropyl ether was best for both the reactions. Vinyl acetate was found as suitable acyl donor in transesterification reaction. A higher amount of enzyme (500 mg) was required for the transesterification of 10 mM substrate; it may be due to the enzyme denaturation by acetaldehyde formed in the reaction. The ester hydrolysis reaction worked well, excellent conversion and de were obtained at 40 °C, pH 7. The 300 mg enzyme hydrolyzed 120 mg (R,S)-FOP acetate with 50% conversion and 99.5% de.