PREPARATION AND LIPASE-CATALYZED OPTICAL RESOLUTION OF 2,2,2-TRIFLUORO-1-(NAPHTHYL)ETHANOLS

The optical resolution of racemic 2,2,2-trifluoro-1-(naphthyl)ethanols (TFNEs) was achieved by lipase-catalyzed enantioselective acetylation with vinyl acetate in octane, S-acetates and R-alcohols being obtained. The introduction of a methyl group into the naphthalene ring at the 4-position (2b) or the 2-position (2c) markedly decreased the reactivity, in particular for 2c. 2,2,2-Trifluoro-1-(1-naphthyl)ethanol (2a) behaved differently from the regio-isomer, 2,2,2-trifluoro-1-(2-naphthyl)ethanol (2d): The enantioselectivity of lipases [LIP (Pseudomonas), PLC (Alcaligenes), and ALC (Achromobacter)] was high for 2a but low for 2d, whereas lipases [AK and PS (Pseudomonas)] exhibited higher selectivity for 2d than for 2a. Three other derivatives, 2,2,2-trifluoro-1-(phenyl)ethanol (2e), 2,2,2-trifluoro-1-(indol-3-yl)ethanol (2f), and 1-(1-naphthyl)ethanol (2g), were prepared, and their behaviors with respect to lipase-catalyzed acetylation were compared with 2a.