Abstract: A process for preparing optically active 3-hydroxy-.gamma.-butyrolactone or optically active 3-hydroxytetrahydrofuran through a short route and by using an easily available and inexpensive starting material and an inexpensive reagent easy to handle is disclosed. The process comprises cyclizing an optically active compound represented by formula (II): ##STR1## wherein Q represents an alkoxycarbonyl group having 1 to 4 carbon atoms or a hydroxymethyl group; X represents a halogen atom; and the asterisk * means an asymmetric carbon atom, under an acidic condition.

Abstract: The present invention provides a novel 2-aralkyl-3-chloropropionic acid and a process for the preparation thereof. A novel 2-aralkyl-3-chloropropionic acid is represented by the general formula (1): ##STR1## and can be prepared by asymmetrically hydrogenating a (Z)-2-aralkylidene-3-chloropropionic acid represented by the general formula (II): ##STR2## with a complex of a bidentate phosphine with ruthenium as a catalyst in the presence of a tertiary amine.