- Synthesis of the racemate of (Z)-exo-alpha-bergamotenal, a pheromone component of the white-spotted spined bug, Eysarcoris parvus Uhler.
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The racemate of (Z)-exo-alpha-bergamotenal, a sex pheromone component of the white-spotted spined bug, was synthesized from racemic exo-alpha-bergamotene by a five-step sequence involving regioselective epoxidation and (Z)-selective Wittig olefination reactions. The 1H- and 13C-NMR spectra of the synthetic sample were identical with those of the natural material.
- Alizadeh, Babak Heidary,Kuwahara, Shigefumi,Leal, Walter Soares,Men, Hong-Chao
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p. 1415 - 1418
(2007/10/03)
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- Synthesis of Terpenes Containing the Bicycloheptane Ring System by the Intramolecular Cycloaddition Reaction of Vinylketenes with Alkenes. Preparation of Chrysanthenone, β-Pinene, β-cis-Bergamotene, β-trans-Bergamotene, β-Copaene, and β-Ylangene and Lemnalol
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Treatment of geranoyl chloride (20) with triethylamine in toluene at reflux gave the vinylketene 21 which underwent a cycloaddition to give 7,7-dimethyl-2-methylenebicycloheptan-6-one (24) in 43percent yield.Isomerization over Pd gave chrysanthenone (6) in quantitative yield.Wolf-Kischner reduction gave β-pinene (5) in 70percent yield.A similar sequence of reactions starting from (Z,E)- and (E,E)-farnesoyl chloride gave ketones 51 and 57, which were converted to β-cis-bergamotene (8) and β-trans-bergamotene (9), respectively. β-Copaene (10) and β-ylangene (11) were prepared from 57 by a three-step sequence.Treatment of the imidazole 59 with tri-n-butyltin hydride in toluene at reflux gave a 46percent yield of a 1:1 mixture of 10 and 11.Selenium dioxide oxidation of 11 gave the antitumor agent lemnalol.The mechanisms of the regiospecific ketene generation and the cycloaddition reaction have been explored, and the reactivity of the novel bicycloheptanones has been examined.
- Kulkarni, Yashwant S.,Niwa, Maho,Ron, Eyal,Snider, Barry B.
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p. 1568 - 1576
(2007/10/02)
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- SIMPLE SYNTHESES OF (+/-)-β-COPAENE, (+/-)-β-YLANGENE AND LEMNALOL.
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The ketone 1a, which we have prepared from geranylacetone in 38percent yield by a four step sequence, has been converted to β-copaene and β-ylangene by a three step secquence.Oxidation of β-ylangene with SeO2 gives lemnalol in 76percent yield.
- Snider, Barry B.,Kulkarni, Yashwant S.
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p. 5675 - 5676
(2007/10/02)
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- Intramolecular Cycloadditions of Ketenes. 2. Synthesis of Crysanthenone, β-Pinene, β-cis-Bergamotene, and β-trans-Bergamotene
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Vinylketenes prepared from geranoyl and farnesoyl chloride by treatment with triethylamine react to give bicycloheptanones which can be converted to β-pinene and the β-bergamotenes by Wolff-Kishner reduction.
- Kulkarni, Yashwant S.,Snider, Barry B.
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p. 2809 - 2810
(2007/10/02)
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- SIMPLE SYNTHESIS OF (+)-β-TRANS-BERGAMOTENE
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(+)-β-trans-Bergamotene (4) has been synthesized in five steps from geranylacetone using intramolecular ketene-olefin cycloadditon as a key step.
- Corey, E. J.,Desai, Manoj C.
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p. 3535 - 3538
(2007/10/02)
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