Reactions of 1,4-Naphthoquinone Derivatives with 1,w-Alkanedithiol
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We study the reaction of 1,4-naphthoquinone and its halogenated derivatives with 1, w-alkanedithiol such as 1,2 ethanedithiol and 1,3-propanedithiol. Five 1,4-naphthoquinones, including 2-chloro-, 2-bromo-, 2,3-dichloro-, and 2,3-dibromo-derivatives, are examined here. For example, the reactions of 1,4-naphthoquinones with 1,2-ethanedithiol went smoothly in methanol at room temperature. In some reactions, hydrochloric acid or N-methylimidazole was added to the reaction mixture. Two products, a spiro compound, 2?-1?,3?-dithiacyclopentane spiro 2-2,3-dihydro-1,4-naphthoquinone derivative and 1,4-dithia-9,10-anthracenedione, are isolated in a reaction mixture. The proportion of these two products is affected by the nature of the starting 1,4-naphthoquinone as well as by the reaction condition, either acidic, neutral, or basic. A spiro compound, 2?-1?,3?-dithiacyclopentane spiro 2-2,3-dihydro-1,4-naphthoquinone derivative is effectively converted to 1,4-dithia-9,10-anthracenedione in the presence of a base in methanol. In the reaction with 1,3-propanedithiol, 2,3-dibromo-1,4-naphthoquinone yielded naphto[2,3-b]-1,5-dithepin-6,11-dione.