Biocatalytic racemization of synthetically important functionalized α-hydroxyketones using microbial cells

Biocatalytic racemization of straight-chain and cyclic acyloins bearing (halo)alkyl, alkenyl and functionalized (hetero)aryl moieties was accomplished using whole resting cells of bacteria, fungi and yeasts. Mild physiological reaction conditions ensured the suppression of undesired side-reactions, such as elimination or condensation. This biocatalytic protocol represents a useful tool for the clean racemization of unwanted enantiomers of synthetically important α-hydroxyketones derived from kinetic resolution.

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(R)-3-Hydroxy-butan-2-oneC4H8O2Ee >99%[α]D20=-61.4 (c 0.2, EtOH)Source of chirality:lipase catalyzed kinetic resolutionAbsolute configuration:(R)

(R)-3-Hydroxy-6-methyl-5-hepten-2-oneC8H14O2Ee >99%[α]D20=+3.8 (c 1.0, CHCl3)Source of chirality:lipase catalyzed kinetic resolutionAbsolute configuration:(R)

(R)-5-Hydroxyoctan-4-oneC8H16O2Ee >99%[α]D20=-13.8 (c 0.5, CHCl3)Source of chirality:lipase catalyzed kinetic resolutionAbsolute configuration:(R)

(R)-1-Hydroxy-1-(4-t-butoxyphenyl)propan-2-oneC13H18O3Ee >99%[α]D20=-49.3 (c 1.8, CHCl3)Source of chirality:asymmetric synthesisAbsolute configuration:(R)

(R)-1-(3-Chlorophenyl)-2-hydroxypropan-1-oneC5H9ClO2Ee >99%[α]D20=+72.8 (c 1.0, CHCl3)Source of chirality:lipase catalyzed kinetic resolutionAbsolute configuration:(R)

(R)-1-(3′,5′-Difluorophenyl)-2-hydroxypropan-1-oneC9H8F2O2Ee >99%[α]D20=+50.0 (c 1.0, CHCl3)Source of chirality:lipase catalyzed kinetic resolutionAbsolute configuration:(R)

(S)-3,3,3-Trifluoro-2-hydroxy-1-phenylpropan-1-oneC9H7O2F3Ee >99%[α]D20=+8.6 (c 0.2, CHCl3)Source of chirality: lipase catalyzed kinetic resolutionAbsolute configuration: (S)

(R)-α-FuroinC10H8O4Ee >99%[α]D20=+62.7 (c 0.9, CHCl3)Source of chirality: lipase catalyzed kinetic resolutionAbsolute configuration: (R)

(R)-α-PyridoinC12H10N2O2Ee >99%[α]D20=+78.8 (c 0.8, CHCl3)Source of chirality: lipase catalyzed kinetic resolutionAbsolute configuration: (R)

(R)-2,2′-DimethoxybenzoinC16H16O4Ee >99%[α]D20=-70.4 (c 1.0, CHCl3)Source of chirality: lipase catalyzed kinetic resolutionAbsolute configuration: (R)

(R)-4,4′-DimethoxybenzoinC16H16O4Ee >99%[α]D20=-87.9 (c 1.3, CHCl3)Source of chirality: lipase catalyzed kinetic resolutionAbsolute configuration: (R)

(R)-2- HydroxycyclohexanoneC6H10O2Ee >99%[α]D20=+20.8 (c 0.65, CHCl3)Source of chirality: lipase catalyzed kinetic resolutionAbsolute configuration: (R)

(R)-2-Hydroxychroman-4-oneC9H8O3Ee = 82%[α]D20=+72.9 (c 0.82, CHCl3)Source of chirality: lipase catalyzed kinetic resolutionAbsolute configuration: (R)