Many quinones are biologically active and beneficial for a variety of medicinal purposes including anticancers. One such example is vitamin K, which could function as an antitumor agent, in addition to its well-known role in blood clotting. This biological activity is ascribed to its modification of the cysteine residue in the active site of tyrosine phosphatase, inhibiting the cell growth of the tumor. Our study involves the introduction of an amino-group including an amino acid side chain, such as lysine, to 1,4-naphthoquinones, and then its reaction with a thiol, such as a cysteine residue, as a model of tyrosine phosphatase. We anticipate the enhanced biological values of our 1,4-naphthoquinone derivatives by adding a desired solubility and membrane permeability so that they are delivered to desired locations in a biological system. In this project, we first study the reactivity of 2-bromo-3-methoxy-1,4-naphthoquinone with L-lysine ethyl ester, which exclusively substitutes the methoxy group at the 3-position. In the second stage of our project, we have attempted to introduce L-cysteine ethyl ester to a 1,4-naphthoquinone with an amino acid side chain. Initially, we reacted an alkyl thiolate in place of an L-cysteine derivative, which resulted in the substitution with the bromine atom of a 1,4-naphthoquinone derivative with an alkylamino group.