Search for Antifouling Sobstances Derived from Ring-Trans-formation of p-Benzoquinone Cycloadducts with 1, 3-Dipoles

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Cycloaddition of p-benzoquinones with 1, 3-Dipoles such as nitrile N-oxides and nitrones has been investigated and site- and regio-selectivity has been shown to be governed by the substituents and substitution pattern of the quinone moieties. The C=C cycloadducts of the quinones with nitrile oxides, 9-aryl-7-oxa-8-azabicyclo[4.3.0]nona-3, 8-diene-2, 5-diones, were shown to undergo base-induced reactions in different patterns also depending on the substituents and substitution pattern of the starting quinones.Some of the cycloadducts underwent isomerization on treatment with a base to give isoxazole-fused cyclohexadienones, which were transformed to isoxazole-fused catechol diacetates by the reaction with acetic anhydride-sulfuric acid.Direct treatment of the cycloadducts with acetic anhydride-sulfuric acid gave isoxazole-fused hydroquinone diacetates.The transformation of the adducts to the catechol or hydroquinone derivative was investigated mainly in terms of substituent effects.The catechol and hydroquinone derivatives obtained were screened for barnaclicidal activity against cypris larva of Balanus amphitrite amphitrite.