抄録
Biocatalyst has been attracted increasing attention for asymmetric synthesis due to the high enantioselectivities and environmentally friendliness. We have been developing methods using a fungus, Geotrichum candidum, which has many enzymes catalyzing the enantioselective oxidation and reduction reactions of non-natural substrates. These enzymes in the resting or dried cells were used in an organic solvent, supercritical carbon dioxide, or aqueous media for oxidation, reduction or deracemization reactions. The usefulness of these methods was also demonstrated in the preparation, on a multi-gram scale, of optically pure alcohols.
The effect of fluorine substituents on the enantioselectivity of the reduction using the dried cell was also investigated thoroughly, and it was found that the reduction of trifluoromethyl ketones affords (S) -trifluoromethyl carbinols in excellent ee, whereas the reduction of methyl ketones gives the corresponding alcohols of the opposite configuration in excellent ee. The enzymes in the cells were separated to investigate the origin of different enantioselectivities between the methyl and trifluoromethyl ketones.
