Enantioselective Biocatalytic Reduction of Non-protected Hydroxyacetophenones

Direct enantioselective reduction of 2´-, 3´- and 4´ -hydroxyacetophenone without protection of the hydroxy moiety was carried out in the presence of (R)- and (S)-alcohol dehydrogenases as biocatalysts. Whereas reduction of 2´-hydroxyacetophenone gave only low to medium conversions, reduction of 3´- and 4´ -hydroxyacetophenone proceeded efficiently leading to the resulting 1-(3- hydroxyphenyl)ethan-1-ol and 1-(4-hydroxyphenyl)ethan-1-ol with high conversion (up to > 95 %) and excellent enantioselectivity (up to > 99% ee).