Asymmetrie Reduction of Synthetic Ketones by Marine Microorganisms

Three strains o f bacteria reducing (trifluoroacetyl)ferrocene (3) to optically pure (R)-2,2,2trifluoro-l-hydroxyethylferrocene (4) and one bacterial strain reducing 3 to (5 )̂-4 o f moderate optical purity were isolated from sea-water collected at the coastal areas in Ibaraki prefecture o f Japan. The former three strains were identified as Micrococcus lylae, Micrococcus luteus, and D eleya marina and the latter as Bacillus licheniformis. These strains also asymmetrically reduced some other synthetic ketones, e.g., 2,2,2-trifluoroacetophenone (7) and phenyl trimethylsilyl ketone (9). Further screening o f microorganisms capable o f reducing 3 was done with bacteria isolated from sea-water o f the deep sea (Okinawa trough, Japan trench, and Mariana trough) and o f the pelagic areas (Indian Ocean and South China Sea). M ost o f these marine strains preferentially reduced 3 to (/?)-4 similar to the coastal strains, but the frequency o f finding very highly enantioselective strains (i.e., those forming 4 o f >90% e.e.) was remark­ ably high in several sites o f the deep sea and pelagic areas as compared with the coast and terrestrial environment.