- An oxidative dearomatization-induced [5 + 2] cascade enabling the syntheses of α-cedrene, α-pipitzol, and sec -cedrenol
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Efficient syntheses of α-cedrene (1), α-pipitzol (2), and sec-cedrenol (3) were carried out using a new method, which was inspired by the proposed biosynthesis of the tricyclic skeleton of cedrol (12). The key transformation begins with the oxidative dearomatization of curcuphenol (5a) followed by an intramolecular [5 + 2] cycloaddition of the respective phenoxonium intermediate across the tethered olefin. The benzylic stereocenter effectively guides the formation of the first two stereocenters during the [5 + 2] reaction. The cascade then terminates with the selective incorporation of acetic acid to generate a third stereocenter, setting it apart from other previous cationic [5 + 2] reactions. The phenolic precursors (5a-h) are constructed from readily available salicylaldehydes, either as the racemate (one pot) or as a specific enantiomer (four pots) by a modification to our method for the generation of ortho-quinone methides (o-QMs).
- Green, Jason C.,Pettus, Thomas R. R.
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p. 1603 - 1608
(2011/04/16)
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- Synthesis of (±)-heliannuol D based on platinum catalyzed regioselective addition of arylboronic acids to allenes
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An alternative total synthesis of (±)-heliannuol D has been achieved in 13 steps and 6.9% overall yield from the arylboronic acid 9. The synthesis applies the previously developed regiocontrolled addition of arylboronic acids to alienes using a platinum catalyst to install the C5 carbon chain on the aryl ring.
- Osaka, Mayu,Kanematsu, Makoto,Yoshida, Masahiro,Shishido, Kozo
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experimental part
p. 1003 - 1012
(2010/10/19)
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- Synthesis of Aromatic Bisabolene Natural Products via Palladium-Catalyzed Cross-Couplings of Organozine Reagents
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Aromatic bisabolene derivatives were prepared by two methods involving cross-coupling of organozinc reagents. The first synthesis of (±)-glandulone A (10), as well as syntheses of (± )-curcuhydroquinone (8) and (±)-curcuquinone (9), were accomplished via coupling of a secondary alkyl zinc reagent (1,5-dimethyl-4-hexenylzinc halide, 18) to protected bromohydroquinones using Pd(dppf)Cl2 as catalyst. Coupling of arylzinc halides with alkenyl triflate 16 using Pd(PPh 3)4 catalyst provided a number of bisabolene derivatives and led to syntheses of dehydro-α-curcumene (2), (±)-curcuphenol (3), and (±)-elvirol (13). A high-yield synthesis of the (±)-heliannuol D precursor 29 is also reported using this method.
- Vyvyan, James R.,Loitz, Celeste,Looper, Ryan E.,Mattingly, Cheryl S.,Peterson, Emily A.,Staben, Steven T.
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p. 2461 - 2468
(2007/10/03)
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- Reaction of methyl 4,5-epoxy-(2E)-pentenoate with arenes. II. Application to the synthesis of(±)-curcudiol, (±)-curcuphenol, (±)-curcuhydroquinone, and(±)-curcuquinone
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Four bisabolane sesquiterpenes, (±)-curcudiol (2), (±)-curcuphenol (3), (±)-curcuhydroquinone (5) and (±)-curcuquinone (6), were synthesized based on the reaction of methyl 4,5-epoxy-(2E)-pentenoate (1) with methoxytoluenes in the presence of boron trifluoride etherate.
- Ono,Yamamoto,Akita
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p. 553 - 558
(2007/10/02)
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- A FACILE SYNTHESIS OF 4-ARYL-5-HYDROXY-(2E)-PENTENOATE DERIVATIVES AND ITS APPLICATIONS TO THE FIRST SYNTHESIS OF (+/-)-CURUCUDIOL, (+/-)-CURCUHYDROQUINONE AND (+/-)-CURCUQUINONE
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The first syntheses of three kinds of bisabolane sesquiterpenes, (+/-)-curcudiol (29), (+/-)-curcuhydroquinone (40) and (+/-)-curcuquinone (41) were achieved based on the BF3*Et2O catalyzed reaction of (+/-) methyl 4,5-epoxy-(2E)-pentenoate (1) and polyme
- Ono, Machiko,Yamamoto, Yasuo,Todoriki, Reiko,Akita, Hiroyuki
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p. 181 - 186
(2007/10/02)
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- New Aromatic Sesquiterpenes from a Halichondria sp.
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Three new aromatic sesquiterpenes have been isolated from a Halichondria sp. found off the Western Australian coast.Evidence is presented for the structure of (1'Z)- and (1'E)-2-(1',5'-dimethylhexa-1',4'-dienyl)-5-methylbenzene-1,4-diol and of (1'E)-2-(1'
- Capon, Robert J.,Ghisalberti, Emilio L.,Jefferies, Phillip R.
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p. 2583 - 2587
(2007/10/02)
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