- Simple synthesis of eudesmin through oxidative coupling of carbanions and reductive catalytic hydrogenation of diketo diester
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A simple synthesis of eudesmin (1) is described. The key fragments were diol 13, dicarbethoxyethane 4, and diketo diester 5, which were prepared via reductive catalytic hydrogenation and oxidative intermolecular coupling of carbanions. This method is useful to generate the core skeleton of an endo-endo furofuran ring. Copyright Taylor & Francis Group, LLC.
- Jung, Jae-Chul,Park, Oee-Sook
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p. 1665 - 1673
(2008/02/01)
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- Stereoselective intramolecular coupling of diaroylacetates of (1R,1′R)-exo,exo′-3,3′-biisoborneol by oxidation with Br 2
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The oxidative coupling of diaroylacetate derivatives prepared from (1R,1′R)-exo,exo′-3,3′-biisoborneol with NaH-Br2 gave the corresponding intramolecularly coupled products stereoselectively. The major (R,R)-isomers thus obtained were transformed to (-)-Sesamin and (-)-Eudesmin.
- Kise, Naoki,Fujimoto, Azumi,Moriyama, Noriaki,Ueda, Nasuo
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p. 2495 - 2497
(2007/10/03)
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- Stereoselective homocoupling of chiral 1-aroylacetyl-2-imidazolidinones by oxidation with Br2
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The oxidative coupling of sodium enolates of (4R,5S)-1-aroylacetyl-3,4-dimethyl-5-phenyl-2-imidazolidinones with Br2 as the oxidant affords the R,R-dimers stereoselectively. The R,R-selectivity can be explained by a radical coupling mechanism.
- Kise, Naoki,Fujimoto, Azumi,Ueda, Nasuo
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p. 1845 - 1847
(2007/10/03)
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- Enantioselective synthesis of natural dibenzylbutyrolactone lignans (-)-enterolactone, (-)-hinokinin, (-)-pluviatolide, (-)-enterodiol, and furofuran lignan (-)-eudesmin via tandem conjugate addition to γ-alkoxybutenolides1,2
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A general and efficient method is described for the asymmetric synthesis of a variety of liguans. 5-(Menthyloxy)-2(5H)-furanones 5 proved to be excellent chiral synthons in this respect and could be transformed with complete stereoselectivity into a number of lignans. The addition of lithiated dithianes 7 to enantiomerically pure butenolides 5 was followed by quenching of the resulting lactone enolate anions with a benzylbromide (9) or with an aldehyde (6). This tandem addition quenching procedure gave the diastereomerically pure adducts 11, 26, or 27 in 50-67% yield, with a carbon skeleton as found in most natural lignans. As examples of the wide applicability of this method, the syntheses of the enantiomerically pure natural lignans (-)-hinokinin (23b), (-)-enterolactone (24a), (-)-pluviatolide (24c), and (-)-enterodiol (25) in overall yields of 29-37% from 5a and (-)eudesmin (30) in 16% overall yield from 5b are described.
- Van Oeveren,Jansen,Feringa
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p. 5999 - 6007
(2007/10/02)
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- Asymmetric 1,4-additions to γ-menthyloxybutenolides. (Part III) Enantioselective synthesis of (-) eudesmin
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Based on an enantioselective Michael addition of the aryldithiane of 3,4-dimethoxybenzaldehyde, to (5S)-menthyloxy-2[5H]-furanone optically pure (-) Eudesmin was synthesized in 16% overall yield.
- Jansen,Feringa
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p. 3239 - 3242
(2007/10/02)
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- Synthesis of 2,6-Diaryl-4,8-dihydroxy-3,7-dioxabicyclooctanes
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A series of 2,6-diaryl-4,8-dihydroxy-3,7-dioxabicyclooctanes, including 4,8-dihydroxysesamin, a naturally occurring lignan, have been prepared via the corresponding dilactones.The 1H and 13C n.m.r. spectra have been compared and the bistoluene-p-sulphonate of 4,8-dihydroxyeudesmin has been reduced by lithium aluminium hydride to give (+/-)-eudesmin.Since this synthesis does not involve ring-opened intermediates and starts from a dilactone of established structure, it represents the first unequivocal synthesis of such a lignan.
- Pelter, Andrew,Ward, Robert S.,Watson, Derrick J.,Collins, Peter,Kay, I. Trevor
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p. 175 - 182
(2007/10/02)
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