PURPOSE: To obtain the new subject derivative useful as an intermediate for producing an optically active cycloalkenecarbolactone such as optically active mitsugashiwactone.

CONSTITUTION: An optically active (2-alkoxycarbonyl-2-cycloalkenyl)acetaldehyde derivative of formula 1 (* is asymmetric carbon; R1 is alkyl, aryl, aralkyl or H; (n) is 14), an optically active (2-alkoxycarbonyl-2-cycloalkenyl)ethanol derivative of formula 2 and an optically active 1-cycloalkenecarbolactone derivative of formula 3. An optically active compound of formula 4 is processed through a compound of formula 4', the new compound of formula 1, the new compound of formula 2 and a new compound of formula 3 and finally alkylated to give an optically active cycloalkenecarbolactone derivative of formula 5 (R2 is alkyl). The compound of formula 5 is obtained in high optical purity in high yield and is useful as a starting substance for medicines agrochemicals, etc.