Selective Baeyer–Villiger oxidation of racemic ketones in aqueous–organic media catalyzed by phenylacetone monooxygenase

The enantioselective kinetic resolution of a set of racemic substituted 3-phenylbutan-2-ones employing phenylacetone monooxygenase (PAMO) in non-conventional media was performed. The studies have revealed the effects of a range of solvents on the biocatalytic properties of the biocatalyst. Also, the enzymatic oxidation of α-acetylphenylacetonitrile was performed using organic cosolvents. This has resulted in a dynamic kinetic resolution of this cyanoketone yielding enantiopure (R)-2-acetoxyphenylacetonitrile with moderate yields depending on the reaction conditions employed.

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(R)-3-(4-Methoxyphenyl)butan-2-oneC11H14O2Ee = 44% (GC, Cydex B)[α]D25=-22.7 (c 1.12, CHCl3)Source of chirality: enzymatic oxidationAbsolute configuration: (R)

(R)-3-(4-Bromophenyl)butan-2-oneC10H11BrOEe = 24% (GC, RtβDEXse)[α]D25=-17.1 (c 1.50, CHCl3)Source of chirality: enzymatic oxidationAbsolute configuration: (R)

(R)-3-(3-Trifluoromethylphenyl)butan-2-oneC11H11F3OEe = 60% (GC, RtβDEXse)[α]D25=-38.7 (c 1.15, CHCl3)Source of chirality: enzymatic oxidationAbsolute configuration: (R)

(S)-1-(3-Trifluoromethylphenyl)ethyl acetateC11H11F3O2Ee = 69% (GC, RtβDEXse)[α]D25=+78.7 (c 0.95, CHCl3)Source of chirality: enzymatic oxidationAbsolute configuration: (S)