Immobilized Manihot esculenta preparation as a novel biocatalyst in the enantioselective acetylation of racemic alcohols

The enzymatic preparation obtained from a discard of Manihot esculenta roots has been successfully immobilized on calcium alginate hydrogels. This preparation has been tested as a chiral biocatalyst in the enzymatic acylation of a set of racemic aromatic alcohols. Depending on the reaction conditions, excellent enantioselectivities can be achieved. Some parameters that can alter the biocatalytic properties of the enzyme, such as solvent, temperature, acyl donor and substrate structure have been studied exhaustively in order to establish a deeper knowledge of this novel biocatalyst.

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(R)-1-(3-Chlorophenyl)ethyl acetateC10H11ClO2Ee = 96% (GC, CP-Chiralsil DEX CB)[α]D25=+15.8 (c 0.80, CH2Cl2)Source of chirality: enzymatic acetylationAbsolute configuration: (R)

(R)-1-(2-Chlorophenyl)ethyl acetateC10H11ClO2Ee = 88% (GC, CP-Chiralsil DEX CB)[α]D25=+9.6 (c 0.64, CH2Cl2)Source of chirality: enzymatic acetylationAbsolute configuration: (R)

(R)-1-(3-Bromophenyl)ethyl acetateC10H11BrO2Ee = 96% (GC, CP-Chiralsil DEX CB)[α]D25=+13.7 (c 0.75, CH2Cl2)Source of chirality: enzymatic acetylationAbsolute configuration: (R)

(R)-1-(3-Methoxyphenyl)ethyl acetateC11H14O3Ee = 95% (GC, CP-Chiralsil DEX CB)[α]D25=+27.8 (c 0.94, CH2Cl2)Source of chirality: enzymatic acetylationAbsolute configuration: (R)

(R)-1-(4-Hydroxyphenyl)ethyl acetateC10H12O3Ee = 95% (HPLC, Chiralcel OB-H)[α]D25=+11.2 (c 1.00, CH2Cl2)Source of chirality: enzymatic acetylationAbsolute configuration: (R)