- Synthetic approach to exo-endo cross-conjugated cyclohexadienones and its application to the syntheses of dehydrobrachylaenolide, isodehydrochamaecynone, and trans-isodehydrochamaecynone
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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 α′-methyl α,β-unsaturated ketones with PTAB and successive dehydrobromination of the resulting α′-bromo-α′-methyl α,β-unsaturated ketones under three conditions (DBU/PhH; TBAF/THF; Li2CO3, LiBr/DMF) gave the desired exo-endo cross-conjugated dienones in good yield. This method was applied to the syntheses of dehydrobrachylaenolide (1), isodehydro-chamaecynone (5c), and trans-isodehydrochamaecynone (11) starting from tuberiferine (7), chamaecynone (5a), and trans-chamaecynone (9). Eudesmanolides possessing an α-methylene γ-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.
- Higuchi, Yohsuke,Shimoma, Fumito,Koyanagi, Rei,Suda, Kouji,Mitsui, Tomokazu,Kataoka, Takao,Nagai, Kazuo,Ando, Masayoshi
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p. 588 - 594
(2007/10/03)
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- Synthesis of Sesquiterpenes, Occidentalol, Chamaecynone and Related Compounds Characterised by a cis-Eudesmane Structure
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In continuation of our synthetic work for constructing the cis-decalin skeleton by a double Michael annulation using 3-methyl-4-methylenecyclohex-2-enone and its congeners with dimethyl 3-oxoglutarate, the sesquiterpenes, occidentalol, chamaecynone, and related compounds have been synthesised in a stereoselective manner.
- Mizuno, Yukio,Mori, Reiko
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p. 2849 - 2854
(2007/10/02)
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