ADH-Catalyzed Biooxidation of (Hetero)aromatic sec-Alcohols to Ketones Employing Vinyl Acetate as Acetaldehyde Surrogate

The oxidation of sec-alcohols is a common reaction in organic chemistry. We report a biocatalytic approach for oxidizing racemic (hetero)aromatic sec-alcohols to the corresponding ketones. The reaction relies on employing freeze-dried E. coli cells containing a recombinant variant of an alcohol dehydrogenase deduced from Lactobacillus kefir (E. coli/Lk-ADH Prince) and vinyl acetate as an in situ acetaldehyde surrogate as oxidant. Biooxidations of a set of 20 racemic (hetero)aromatic alcohols were carried out in the presence of a catalytic amount of NADP⁺ cofactor, the biocatalyst, and vinyl acetate in an aqueous medium to generate the corresponding ketones with up to >99 % conv. Preparative scale (1.0 mmol; 100 mM in 10 mL) reactions led to obtaining ketones in the 56–83 % isolated yield range.