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Reactions of 2-Alkylthio-3-methyl-1,4-naphthoquinones with Alkylamines Derivatives of
1,4-naphthoquinone play an important role in various biological
processes through reactions with a nucleophile. For example, the
anticancer activities in tyrosine phosphatase are due to the reactivity
of 1,4-naphthoquinones with a nucleophilic cysteine residue in the
active site. Here we study the reactivity of
2-alkylthio-3-methyl-1,4-naphthoquinones against amines, one of the
important nucleophiles in the biological environment. We first
synthesized 2-alkylthio-3-methyl-1,4-naphthoquinone from the reaction of
2-methyl-1,4-naphthoquinone epoxide with alkanethiol in the presence of
N-methylimidazole, a weak base. Then we reacted
2-alkylthio-3-methyl-1,4-naphthoquinone with various alkylamines. The
alkylthiols studied were methylthiol, ethylthiol, 1-propanethiol, and
2-propanethiol, and the alkylamines studied were methylamine,
ethylamine, and isopropylamine. The product is
2-alkylamino-3-alkylthio-1,4-naphthoquinone through demethylation. In
the presence of oxygen, 2-alkylthio-3-methyl-1,4-naphthoquinone epoxide
also was efficiently formed. However, in the reactions under argon
atmosphere, the formation of epoxide was completely excluded, and only
2-alkylamino-3-alkylthio-1,4-naphthoquinone is detected. Support provided by: Mary S. Caswell Endowment |
