- Titanium-catalyzed enantioselective synthesis of α-ambrinol
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We describe the first enantioselective synthesis of the odorant compound (-)-α-ambrinol (96% ee) from commercial geranylacetone. The key steps are a Jacobsen's asymmetric epoxidation and a titanium-catalyzed stereoselective cyclization initiated by radical epoxide opening. The oxirane ring opening proceeds with retention of configuration at the epoxide chiral center, giving a secondary alcohol which can be advantageously exploited to raise the ee provided by the synthetic sequence. We also synthesized (+)-α-ambrinol by a closely related procedure, showing the synthetic versatility of combining titanium-catalyzed cyclization with Jacobsen's epoxidation reactions.
- Justicia, Jose,Campan, Araceli G.,Bazdi, Btissam,Robles, Rafael,Cuerva, Juan M.,Oltra, J. Enrique
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experimental part
p. 571 - 576
(2009/05/07)
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- Biomimetic cyclization of small terpenoids promoted by zeolite NaY: Tandem formation of α-ambrinol from geranyl acetone
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Zeolite NaY promotes efficiently the biomimetic cyclization of small acyclic terpenes. Geranyl and neryl acetone undergo a novel tandem 1,5-diene cyclization/carbonyl-ene reaction to form the natural product α-ambrinol isolated in >65% yield.
- Tsangarakis, Constantinos,Stratakis, Manolis
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p. 1280 - 1284
(2007/10/03)
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- New Synthesis of γ-Homocyclogeranial, γ-Dihydroionone and Their Derivatives
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A new and efficient synthesis of γ-homocyclogeranial (4), γ-dihydroionone (3) and their derivatives, 5, 6, 7 and 8, volatile components of ambergris, is described.Their compounds were synthesized via Claisen rearrangement of (3,3-dimethylcyclohexenyl)methyl vinyl ether (14).
- Kawanobe, Tsuneo,Kogami, Kunio,Hayashi, Kazuo,Matsui, Masanao
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p. 461 - 464
(2007/10/02)
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- Ambrinol and its homologues
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Compounds useful as fragrance materials having the structure STR1 wherein each of R1, R2, and R3 are hydrogen or methyl can be prepared by reacting a halogen-containing cyclohexane, having the structure STR2 wherein each of R1, R2, and R3 are hydrogen or methyl and X is a halogen, with a reagent capable of effecting intramolecular cyclization.
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- SYNTHESIS OF (+/-)-α-AMBRINOL
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Synthesis of α-ambrinol was successfully accomplished by cyclization of dihydro-γ-ionone ethylene acetal which was prepared by the titanium(IV)-promoted reaction of 3,3-dimethyl-1-trimethylsiloxycyclohexene with methyl vinyl ketone ethylene acetal followed by exomethylenation with triphenylphosphonium methylide.
- Takazawa, Osamu,Tamura, Hiroshi,Kogami, Kunio,Hayashi, Kazuo
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p. 1257 - 1258
(2007/10/02)
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