- Stereoselective Synthesis of (E)-α-Hydroxy-1,3-dienes via the Reaction of 2,5-Dihydrothiophene S,S-Dioxides with Carbonyl Compounds
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A stereoselective synthesis of (E)-α0hydroxy -1,3-dienes, by thermal extrusion from adducts of 2,5-dihydrothiophene S,S-dioxide(1) with aldehydes and ketones, is presented and its extension to the synthesis of the dienone, (E)-tagetone, and of a 1,3,5-triene system, is illustrated.
- Yamada, Sachiko,Suzuki, Hiromasa,Naito, Hiroyuki,Nomoto, Takashi,Takayama, Hiroaki
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- Stereoselective Synthesis of (E)-Tagetone
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(E)-Tagetone (8) was prepared in four steps by successive alkylation of 1,3-dithiane (1) by 1-iodo-2-methylpropane (2) and by 3-ethoxy-2-methylacrolein (3), followed by treatment of the intermediate 4 with sulfuric acid.Wittig alkylenation of the resulting aldehyde 5 and removal of the protecting group affords the title compound in good yield. - Key Words: Tagetes glandulifera / (E)-Tagetone / 1,3-Dithiane / Oxopropylenation / Wittig alkylenation
- Kunz, Joachim,Breitmaier, Eberhard
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p. 707 - 708
(2007/10/02)
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- ACYLATION OF 1,3-ALKADIENES BY ACYL FLUOROSULFONATES. STEREOSPECIFIC SYNTHESIS OF E AND Z ISOMERS OF CONJUGATED DIENONES
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Acyl fluorosulfonates generated from acyl fluorides and SO3 permits acylation of butadiene and isoprene to give triconjugated dienones.This reaction proceeds stereospecifically and leads to E isomers of the corresponding dienones in the case of butadiene and Z isomers in the case of isoprene.
- Gavrishova, T.I.,Shastin, A.V.,Balenkova, E.S.
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p. 580 - 583
(2007/10/02)
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- Reactions with α,β-Unsaturated Nitrile Oxides. Synthetic Studies in the Terpene Field. Synthesis of Tagetones, Ocimenones, Deodarone and Atlantone
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The generation and 1,3-dipolar cycloaddition of α,β-unsaturated nitrile oxides are described.Selective reductive cleavage of the isoxazoline ring was achived.Subsequent elimination of water leads to the 1,4-dien-3-one system.The formation of tetrahydro-γ-pyrones is observed.The reactions were applied to the synthesis of tagetones, ocimenones, deodarone and atlantone.
- Isager, Per,Thomsen, Ib,Torssell, Kurt B. G.
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p. 806 - 813
(2007/10/02)
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- Trityl Salt Catalyzed Aldol Reaction between α,β-Acetylenic Ketones and Silyl Enol Ethers
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In the presence of a catalytic amount of trityl salt, α,β-acetylenic ketones react with silyl enol ethers to afford the corresponding aldol adducts (1,2-addition products) stereoselectively in high yields.Naturally occurring monoterpenes, trans- and cis-tagetones, are synthesized by the use of this reaction.
- Kobayashi, Shu,Matsui, Shigekazu,Mukaiyama, Teruaki
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p. 1491 - 1494
(2007/10/02)
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- REACTIONS OF UNSATURATED COMPOUNDS. CXIII. THE STEREOCHEMISTRY AND REGIOCHEMISTRY OF THE ACYLATION OF CONJUGATED SYSTEMS
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The stereochemistry and regiochemistry of the low-temperature acylation of vinylacetylene, chloroprene, bromoprene, and isoprene with carboxylic acid chlorides in the presence of aluminum chloride were studied.It was shown that mixtures of the geometric isomers of 3-chloro-1,3-alkadien-5-ones are formed in the case of vinylacetylene, and 1,4-adducts (which undergo stereoselective 1,4-dihydrochlorination with the preferential formation of cis-3-X-1,3-alkadien-5-ones) are formed in the other cases. cis-Tagetone was synthesized with a stereoisomeric purity of 83percent.
- Melikyan, G. G.,Babayan, E. V.,Atanesyan, K. A.,Badanyan, Sh. O.
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p. 1884 - 1889
(2007/10/02)
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- CONDENSATION DES NITRILES AVEC LES ORGANOZINCIQUES ALLYLIQUES. APPLICATIONS EN SERIE TERPENIQUE
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The reaction of 3-bromomethyl-2,5-dihydrothiophen-1,1-dioxide 6 and 2-bromomethyl-1,3-butadiene 7 with nitriles in the presence of the zinc-silver couple leads to a mixture of ketones 8,9, the pyrolysis of which give the ketones 10 and 11, corresponding respectively to acylation of isoprene at its methyl group from 8, and at C-3 from 9.The reaction of bromide 7 with nitriles leads also to the formation of ketones 10 which by acid isomerisation give the ketones 12 corresponding to an acylation at C-1 of isoprene.In the same way the reaction of 2-(1'-methyl-4'-cyclohexenyl)-3-bromo propene 13 with 3,3-dimethyl acrylonitrile give β- atlantone 14 which is isomerised in acidic medium to α-atlantone 15. 10,11-dihydro α and β-atlantone 16, 17 are obtained by the same procedure from 13 and 3-methyl butyronitrile.
- Rousseau, G.,Drouin, J.
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p. 2307 - 2310
(2007/10/02)
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- NEW METHOD FOR REGIOSELECTIVE SYNTHESIS OF α-SUBSTITUTED ALLYLSILANES AND ITS APPLICATION TO THE SYNTHESIS OF E- AND Z-TAGETONES
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Sequential addition of lithium salt of carbanion and tributylstannylmethyl iodide (3) to vinyl sulfone 2 afforded β-tributylstannyl sulfones 5, which gave substituted allylsilanes 1 in a regioselective manner by the smooth destannylsulfonation.Allylsilane 8 prepared by Michael type addition of isopropenyllithium to 2 was converted into tagetones (10). Keywords --- allylsilane; β-trimethylsylilvinyl sulfone; destannylsulfonation; tributylstannylmethyl iodide; tagetone; Michael addition
- Ochiai, Masahito,Sumi, Kenzo,Fujita, Eiichi,Tada, Shin-ichi
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p. 3346 - 3349
(2007/10/02)
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