A FACILE PREPARATION OF ENANTIOMERS OF ETHYL 4,4,4-TRIFLUORO-3(INDOLE-3-)BUTYRATE, A NOVEL PLANT-GROWTH REGULATOR

Malonic ester synthesis combined with lipase-catalyzed enantioselectiv e partial hydrolysis was used to prepare enantiomers of ethyl 4,4,4-tr ifluoro-3-(indole-3-)butyrate, a novel plant growth regulator. Among s ix commercially available enzymes, lipase AK (a lipase from Pseudomona s sp.) showed high enantioselectivity and moderate reactivity. The hyd rolysis of racemic diethyl 2,2,2-trifluoro-1-(indole-3-)ethylmalonat ( DTFIE) with lipase AK gave, following usual treatment of the products, S-(+)-4,4,4-trifluoro-3-(indole-3-)butyric acid (TFIBA) ethyl ester h aving 95% e.e. and R-(-)-TFIBA ethyl ester having >99% e.e. The optimi zed conditions for lipase AK hydrolysis were 0.1 M phosphate buffer (p H 6.0) containing 10% hexane at 45 degrees C.