- Total Synthesis and Structure Revision of (-)-Illisimonin A, a Neuroprotective Sesquiterpenoid from the Fruits of Illicium simonsii
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Illisimonin A was isolated from Illicium simonsii and has a previously unreported tricyclic carbon framework. It displayed neuroprotective effects against oxygen-glucose deprivation-induced cell injury in SH-SY5Y cells. It incorporates a highly strained trans-pentalene ring system. We report the first synthesis of (±)-illisimonin A. Notable steps in the route include a 1,3-dioxa-2-silacyclohexene templated Diels-Alder cycloaddition and type-3 semipinacol rearrangement to generate the trans-pentalene. The final step is an iron-catalyzed C-H oxidation. The synthetic route is robust, with 94 mg of racemic material prepared in a single pass. Resolving an intermediate enabled the synthesis of natural (-)-illisimonin A. The absolute configuration of (-)-illisimonin A was revised to 1S,4S,5S,6S,7R,9R,10R based on the X-ray structure of a heavy-atom analogue.
- Burns, Alexander S.,Rychnovsky, Scott D.
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- Synthesis of the complete carbocyclic skeleton of vinigrol
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(Matrix presented) An efficient entry to the fully elaborated skeleton of vinigrol is described. The installation of the desired stereochemistry at C(12) and the construction of the eight-membered ring were achieved in one operation by a remarkably facile anionic oxy-Cope rearrangement of Z-isopropenyl isomer 24.
- Gentric, Lionel,Hanna, Issam,Ricard, Louis
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p. 1139 - 1142
(2007/10/03)
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- Unexpected MIMIRC Annulation Between a Lithium Dienolate and Methyl Acrylate
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We describe an unusual MIMIRC reaction between a lithium dienolate 6 and methyl acrylate.The more classical double Michael addition cyclisation provides an efficient entry towards key intermediate 5 for 2-isocyanopupukeanane 1 synthesis.
- Jaafar, Akram,Alilou, El Houssine,Reglier, Marius,Waegell, Bernard
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p. 5531 - 5534
(2007/10/02)
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