(2) A compound represented by Formula I, where Z is a single bond, Y is --COO--, and X2 is --OCO--, can be synthesized by the following method, using the optically active substance represented by Formula IV as part of its material. ##STR11## where R1 and R2 are the same or different straight-chain or branched chain alkyl groups having 1 to 15 carbon atoms; X1 is a single bond, --O--, --COO--, or -