An Efficient Method of Preparing (R)- and (S)-4,4,4-Trifluoro9-3-hydroxybutanoic Acid: Resolution with (R)- or (S)-1-Phenylethylamine

Abstract

Two crystallizations of the unlike salts 2 from 4,4,4-trif1uoro-3-hydroxybutanoic acid (1) and 1-phenylethylamine, followed by recovery of the free acid, lead to the isolation, in ca. 30% (60% of the theoretical amount), of the (R)- and (S)-acid 1 (m.p. 44°) in ? 98 % enantiomeric excess. The purity of 1 was determined by Mosher's method,and the sense of chirality (+)-(R) and (?)-(S) determined by chemical correlation. The resolution procedure leading to enantiomerically pure 1 is compared with the methods using enzymatic or microbial enantioselective reactions.