Hydrochloric Acid → (+)-Suprofen

Participants

Reaction Conditions

Reaction Steps

To 100 mg crude Candida cylindracea lipase (Sigma L1754 Type VII, 500 units/mg solid) in 4 mL 0.2M phosphate buffer, pH 7.0, was added 200 mg (±)-α-methyl-4-(2-thienylcarbonyl)benzeneacetic acid methyl ester (suprofen methyl ester). The resulting suspension was gently stirred with a magnetic stirrer for 48 hours at 22° C. The reaction mixture was acidified to pH 1.0 with 1N HCl and exhaustively extracted with ethyl acetate three times. The combined organic extract was dried over sodium sulfate and was then evaporated to dryness. The residue was chromatographed over a silica gel (MN Kieselgel 60) column (0.8×15 cm). Elution of the column with a solvent system consisting of ethyl acetate-hexane (1:5) gave unreacted (R)-α-methyl-4-(2-thienylcarbonyl)benzeneacetic acid methyl ester, [α]D25 =-54.7° (c=3.9, CHCl3), ee>0.90, and (S)-α-methyl-4-(2-thienylcarbonyl)benzeneacetic acid, [α]D25 =+43.5° (c=2.1, CHCl3), ee>0.95. The optical purity expressed as enantiomeric excess (ee) is determined by proton magnetic resonance spectroscopy of the methyl ester in the presence of the chiral lanthanide shift reagent, Eu(hfc)3.

Provenance & Evidence