Rhizopus arrhizus-mediated asymmetric reduction of arylalkanones: unusual anti-Prelong products with benzyl alkyl ketones

Rhizopus arrhizus-mediated microbial reduction of various aryl alkyl ketones afforded chiral carbinols in good yields and high enantiomeric purity. The most striking feature was the formation of the anti-Prelog (R)-alcohols with the benzyl alkyl ketones, while the other ketones ArXCOR (X = (CH2)n, n = 0 or 2, OCH2 or SCH2 and R = Me/Et/n-Bu) furnished (S)-alcohols.

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(R)-1-(4′-Fluorophenyl)propan-2-olC9H11FOEe = 37%[α]D24=-29.2 (c 2.25, CHCl3)Source of chirality: microbial reductionAbsolute configuration: (R)

(R)-1-(4′-Methoxyphenyl)propan-2-olC10H14O2Ee = 87%[α]D24=-26.3 (c 2.57, CHCl3)Source of chirality: microbial reductionAbsolute configuration: (R)

(R)-1-(3′,4′-Dimethoxyphenyl)propan-2-olC11H16O3Ee = 90%[α]D24=-22.2 (c 3.12, CHCl3)Source of chirality: microbial reductionAbsolute configuration: (R)

(R)-1-Phenylbutan-2-olC10H14OEe = 99%[α]D24=-31.1 (c 2.82, CHCl3)Source of chirality: microbial reductionAbsolute configuration: (R)

(R)-1-Phenylhexan-2-olC12H18OEe = 99%[α]D24=-17.2 (c 1.18, CHCl3)Source of chirality: microbial reductionAbsolute configuration: (R)

(S)-4-Phenylbutan-2-olC10H14OEe = 95%[α]D24=+15.3 (c 3.32, CHCl3)Source of chirality: microbial reductionAbsolute configuration: (S)

(S)-4-(4′-Methoxyphenyl)butan-2-olC11H16O2Ee = 94%[α]D24=+13.1 (c 3.07, CHCl3)Source of chirality: microbial reductionAbsolute configuration: (S)

(S)-1-Phenoxypropan-2-olC9H12O2Ee = 95%[α]D24=+25.2 (c 3.06, CHCl3)Source of chirality: microbial reductionAbsolute configuration: (S)

(S)-1-(4′-Chlorophenylthio)propan-2-olC9H11ClOSEe = 97%[α]D24=+41.9 (c 1.18, CHCl3)Source of chirality: microbial reductionAbsolute configuration: (S)