title: Synthetic approach to exo-endo cross-conjugated cyclohexadienones and its application to the syntheses of dehydrobrachylaenolide, isodehydrochamaecynone, and trans-isodehydrochamaecynone.
abstract: Methodology for synthesis of exo-endo cross-conjugated dienones with trans- and cis-decalin systems has been reported. Bromination of the silyl enol ether of alpha'-methyl alpha,beta-unsaturated ketones with PTAB and successive dehydrobromination of the resulting alpha'-bromo-alpha'-methyl alpha,beta-unsaturated ketones under three conditions (DBU/PhH; TBAF/THF; Li(2)CO(3), LiBr/DMF) gave the desired exo-endo cross-conjugated dienones in good yield. This method was applied to the syntheses of dehydrobrachylaenolide (1), isodehydrochamaecynone (5c), and trans-isodehydrochamaecynone (11) starting from tuberiferine (7), chamaecynone (5a), and trans-chamaecynone (9). Eudesmanolides possessing an alpha-methylene gamma-lactone moiety, i.e., 1, 7, and 13, exhibited significant inhibitory activity toward the induction of the intercellular adhesion molecule-1 (ICAM-1). Compound 1 showed greater activity than 7 and 13. All compounds possessing an ethynyl group, 5d, 9, 11, and 14, showed the same degree of termiticidal activity, and the exo-endo cross-conjugated dienone structure in 11 had no influence on the activity.
authors.affiliation: Graduate School of Science and Technology, and Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University, 2-8050 Ikarashi, Japan.
authors.forename: Yohsuke
authors.initials: Y
authors.lastname: Higuchi
authors.forename: Fumito
authors.initials: F
authors.lastname: Shimoma
authors.forename: Rei
authors.initials: R
authors.lastname: Koyanagi
authors.forename: Kouji
authors.initials: K
authors.lastname: Suda
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Mitsui
authors.forename: Takao
authors.initials: T
authors.lastname: Kataoka
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nagai
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Ando
mesh_terms: D000818:Animals; D003510:Cyclohexanes; D007306:Insecticides / Q000138:chemical synthesis* / Q000494:pharmacology; D018799:Intercellular Adhesion Molecule-1 / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D020049:Isoptera / Q000187:drug effects; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D012717:Sesquiterpenes / Q000138:chemical synthesis* / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D003510:Cyclohexanes; D007306:Insecticides; D007375:Interleukin-1; D009281:Naphthalenes; D012717:Sesquiterpenes; C477989:dehydrobrachylaenolide; C477990:isodehydrochamaecynone; D018799:Intercellular Adhesion Molecule-1; C007229:decalin