Stereochemical preference of Candida parapsilosis ATCC 7330 mediated deracemization: E- versus Z-aryl secondary alcohols

The stereochemical preference of the biocatalyst, Candida parapsilosis ATCC 7330, was investigated with respect to the E/Z configuration in the deracemization and the asymmetric reduction of aryl secondary alcohols and prochiral ketones, respectively. The biocatalyst preferred the E-isomers over Z-isomers as substrates as evidenced from the experimental results of >99% ee and up to 86% isolated yield for E-secondary alcohols. The synthesis of enantiomerically pure E-4-phenylbut-3-ene-1,2-diol (ee >99%, isolated yield 86%) by whole cell mediated deracemization is reported here for the first time. The geometric preference of the enzymes was confirmed by using the cell free extract of this biocatalyst. Mechanistic insights using in silico studies showed that the E-isomers when located in the active site are favourably placed with respect to the catalytic triad (Ser-Tyr-Lys) for hydride transfer from NADPH.

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(S,E)-Ethyl 2-hydroxy-4-phenylbut-3-enoateC12H14O3ee = >99[α]D25=+70.4 (c 1, CHCl3)Source of Chirality: Biocatalytic deracemizationAbsolute configuration: (2S)

(S,E)-Methyl 2-hydroxy-4-phenylbut-3-enoateC11H12O3ee = >99[α]D25=+115.2 (c 1, MeOH)Source of Chirality: Biocatalytic deracemizationAbsolute configuration: (2S)

(S,E)-Ethyl 3-hydroxy-5-phenylpent-4-enoateC13H16O3ee = >99[α]D25=-6.8 (c 0.5, CHCl3)Source of Chirality: Biocatalytic deracemizationAbsolute configuration: (2S)

(R,E)-4-Phenylbut-3-en-2-olC10H12Oee = >99[α]D25=+17.8 (c 1, MeOH)Source of Chirality: Biocatalytic deracemizationAbsolute configuration: (2R)

(S,E)-4-Phenylbut-3-ene-1,2-diolC10H12O2ee = >99[α]D25=+28.8 (c 1, CHCl3)Source of Chirality: Biocatalytic deracemizationAbsolute configuration: (2S)

(S,Z)-Ethyl 2-hydroxy-4-phenylbut-3-enoateC12H14O3ee = >99[α]D25=+320.6 (c 1, CHCl3)Source of Chirality: Biocatalytic deracemizationAbsolute configuration: (2S)