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Antitermite activity of 7-alkoxycoumarins and related analogs against Coptotermes formosanus Shiraki

Adfa, Morina, Hattori, Yosuke, Yoshimura, Tsuyoshi, Koketsu, Mamoru
International biodeterioration & biodegradation 2012 v.74 pp. 129-135
Coptotermes formosanus, antifeedants, antifeeding activity, benzene, coumarin, halides, potassium carbonate, skeleton
Twenty-three 7-alkoxycoumarins and related analogs were synthesized from 7-hydroxycoumarin by treatment with various alkyl/aryl/acyl halides and potassium carbonate in DMF. Their antifeedant and termiticidal activities against Coptotermes formosanus Shiraki were examined. Among the 23 compounds and control, 7-cyclohexyloxycoumarin (2k), exhibited the highest termiticidal activity in no-choice test, followed by 7-(4-nitrophenoxy)coumarin (2q), and 7-(2-butynyloxy)coumarin (2u) at 5 μmol/disc. On the other hand, all of 7-alkoxycoumarins showed antifeedant activity except 7-hexadecyloxycoumarin (2i) and 7-octadecyloxycoumarin (2j), while 7-ethoxycoumarin (2b) demonstrated the highest antifeedant activity. The results suggested that a presence of cyclohexyloxy and aryloxy groups at C-7 position of coumarin skeleton was found to be important for the termiticidal and antifeedant activities. Arylalkoxy groups having methoxy groups at benzene ring, alkenoxy, and alkynoxy groups led to analogs with good termiticidal activity, while the incorporation of alkoxy groups with longer alkyl chains tended to reduce both the termiticidal and antifeedant activities.