Lysosomotropic detergents (cytotoxic compounds designed as anticancer agents) acylated with Z-GlyPhe (N-benzyloxycarbonyl-L-glycyl-L-phenlylalanine, masking into cells!,are facilitated entry into the target cells. In this study, the precursor of Z-GlyPhe, namely Z-GlyPheOMe (N-benzyloxycarbonyl -L-glycyl-L-phenlylalanine methyl ester), is enzymatically synthesized continuously utilizing an extractive reaction. The yield of Z-GlyPheOMe is usually ca. 10 % in aqueous medium due to the unfavorable shift of the chemical equilibrium towards a peptide bond hydrolysis. Since this peptide precursor is non-ionic, the precursor was distributed to an organic phase in an aqueous/organic biphasic system. Z-GlyPheOMe is selectively extracted into the organic phase simultaneously with an enzymatic synthesis in an aqueous enzyme solution in an aqueous/organic biphasic system, and ca. 100 % yield of Z-GlyPheOMe is achieved.