- Cyclization of 1,5-dienes: An efficient synthesis of β-Georgywood
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(Chemical Equation Presented) In the acid-promoted 1,5-diene cyclization of pseudo- to β-Georgywood, the cyclization product is obtained with high selectivity in spite of an unfavorable substituent at the C(2)-position of the diene precursor. Preisomeriza
- Frater, Georg,Schroeder, Fridtjof
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- Synthesis and olfactory properties of (-)-(1R,2S)-Georgywood
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The enantiomers of Georgywood were synthesized from (E)-2-methyl-6-methylene-nona-2,7-diene and methacrylaldehyde followed by oxidation of the Diels-Alder adduct and classical racemate separation of the acid with optically-active N-methylephedrine. Conversion to the final ketone and olfactory evaluation showed that the (-)-(1R,2S)-enantiomer is more powerful by a factor of >100 than its antipode. The absolute configuration was determined by conformational studies and CD-analysis.
- Frater, Georg,Mueller, Urs,Schroeder, Fridtjof
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- Endo-selective Diels-Alder reaction of methacrylonitrile: application to the synthesis of Georgywood
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Diels-Alder reactions of alkyl-substituted dienes with acrylonitriles give good yields and endo-selectivities if catalyzed by (organo)aluminum, (organo)boron or gallium halides. The activity of these group IIIa Lewis acids in this reaction correlates with
- Borosy, Andras,Frater, Georg,Müller, Urs,Schr?der, Fridtjof
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experimental part
p. 10495 - 10505
(2010/02/28)
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- Enantioselective syntheses of georgyone, arborone, and structural relatives. Relevance to the molecular-level understanding of olfaction
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Georgyone (1) and arborone (2), powerful woody odorants, have been synthesized enantioselectively along with their enantiomers. Several structural relatives of 1 and 2 have also been made enantioselectivity in order to probe the molecular details of the b
- Hong, Sungwoo,Corey
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p. 1346 - 1352
(2007/10/03)
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- PROCESS FOR THE PREPARATION OF CIS-2-ACETYL-1, 2, 3, 4, 5, 6, 7, 8-OCTAHYDRO-1, 2, 8, 8-TETRAMETHYLNAPHTHALENE
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A process of preparation of cis-2-acetyl-1,2,3,4,5,6,7,8-octahydro-1,2,8,8-tetramethylnaphthalene ("?-Georgywood") from cis-1-[1,2-dimethyl-4(4-methyl-pent-3-enyl)-cyclohex-3-enyl]-ethanone (“Ψ -Georgywood"), comprising the reaction of Ψ-Georgywood with more than one molar equivalent of a Lewis acid. The method allows the preparation of isomeric mixtures that contain a much higher proportion of the olfactorily-desirable ?-Georgywood than was previously possible.
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Page/Page column 6
(2008/06/13)
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- PROCESS FOR THE PREPARATION OF METHYLALUMINIUM DICHLORIDE
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A process of preparing methylaluminium dichloride by (i) reacting by heating a material of the formula R3Al2X3, where R is C1-C4 alkyl and X is selected from bromine and iodine with an aluminium-containing material selected from metallic aluminium and a mixture of metallic aluminium and aluminium trichloride in an atmosphere of methyl chloride, with the proviso that when R is methyl and X is iodine, the aluminium-containing material is a mixture of aluminium and aluminium trichloride; and (ii) when the aluminium-containing material is metallic aluminium, adding aluminium trichloride to this reaction mixture and heating, to give a crude reaction product; and (iii) if desired, obtaining methylaluminium dichloride from this crude reaction product. The crude reaction product may be used directly in organic syntheses, such as the cyclisation of ψ-Georgywood to give ?-Georgywood.
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Page/Page column 8
(2008/06/13)
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- Chemistry of odorants: Stereoselective synthesis of octahydronaphthalene- based perfumery Georgywood, (+,-)-1-[(1R*,2S*)-1,2,3,4,5,6,7,8- octahydro-1,2,8,8-tetramethylnaphthalen-2-yl]ethan-1-one
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A straightforward synthesis of octahydronaphthalene-based fragrance, such as Georgywood, is described. The Lewis acid tin (IV) chloride catalyzed efficiently an original one-pot sequential cycloaddition-clyclization process by reaction of myrcene with 3-bromo-but-3-en-2-one, leading directly to the octahydronaphthalene skeleton in very good yields (85%). Then, dehydrohalogenation with DBU gave the key 2,4-dienone intermediate in excellent yield (85%). Regioselective Michael addition gave rise to the formation of the addition product as a trans/cis diastereoisomeric mixture, by reaction either with CH3Cu·BF3 (6:1 ratio, 70%) or (CH 3)2CuLi/TMSCl reagents (3:1 ratio, 80%). The generation of thermodynamically more stable enolate by treatment of the diastereoisomeric mixture with sodium hydride in tetrahydrofuran in the presence of an excess of methyl iodide, allowed stereoselective introduction of the methyl group at C2, leading to the formation of Georgywood in good yield (60%), as the only diastereoisomer, with a trans stereochemistry of the two methyl groups as demonstrated by NMR experiments.
- Bella, Marco,Cianflone, Marcello,Montemurro, Gabriele,Passacantilli, Pietro,Piancatelli, Giovanni
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p. 4821 - 4827
(2007/10/03)
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