- Steric effects in hula-twist photoisomerization. 1,4-Dimethyl- and 2,3-dimethyl-1,4-diphenylbutadienes
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1,4-Dimethyl-1,4-diphenylbutadiene was shown to be able to execute regiospecific HT-1 photoisomerization around a methyl group when irradiated in a low-temperature organic glass, albeit at reduced efficiency. 2,3-Dimethyl-1,4-diphenylbutadiene exhibited a different type of steric effect, causing the E,E-isomer to undergo regiospecific HT-1 photoisomerization. Copyright
- Yang, Lan-Ying,Liu, Robert S. H.,Wendt, Natalie L.,Liu, Jin
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- Synthesis of Substituted 1,3-Dienes by the Reaction of Alkenylsulfonyl Chlorides with Olefins Catalyzed by a Ruthenium(II) Complex
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Alkenylsulfonyl chlorides reacted with vinylarenes in the presence of a catalytic amount of dichlorotris(triphenylphosphine)ruthenium(II) to give substituted adducts, which were dehydrochlorinated and desulfonylated successively to form substituted (E,E)-1,3-dienes in good yield.
- Kameyama, Masayuki,Shimezawa, Hiroshi,Satoh, Takeshi,Kamigata, Nobumasa
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p. 1231 - 1236
(2007/10/02)
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- Comparative Studies on the Addition Reactions of the Normant Reagent ("CH3MgBr" + CuBr) and the New Tetrahydrofuran-Soluble Magnesium Methylcuprates MgmCun(CH3)2m+n with Phenylacetylene
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Reactions of phenylacetylene with the Normant reagent ("CH3MgBr" + CuBr) and the THF-soluble magnesium methyl cuprates MgmCun(CH3)2m+n obtained from the reaction of (CH3)2Mg with CuBr have been studied in detail.An attempt to determine the reactive species in Normant reagents was made by studying the rate of reaction of the Normant reagent with phenylacetylene compared to the rate observed with various magnesium methylcuprates.Cu4Mg(CH3)6 and Cu6Mg(CH3)8 have been shown to be the most probable candidates responsible for reactions involving the Normant reagent with alkynes.The effect of MgBr2 and LiBr on the reactivity and the product selectivity has also been studied.
- Ashby, E. C.,Smith, R. Scott,Goel, A. B.
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p. 5133 - 5139
(2007/10/02)
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- R3Cu2M Species: Convenient cuprates for the conversion of 1-alkynes into 1-alkenes
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The paper describes reactions of 1-alkynes, R1-CC-H, with new cuprate species of the type R3Cu2M .Under suitably chosen conditions a smooth transfer of R (Me or Et) from the cuprates to the 1-alkynes (R1 = Ph or n-C6H13) could be realized.The resulting stereospecifically generated adducts 1C=CH)xCu2R3-x>Mg (Cl or Br) were stable under the conditions of the reactions, provided that a sufficient amount of lithium bromide was present.In the absence of lithium bromide substantial decomposition of the adducts into RR1C=CH-CH=CRR1 took place.During the reaction of PhCCH with Me3Cu2Li the addition reaction was accompanied by deprotonation, which could be proved by using PhCCD as starting alkyne.Deprotonation in PhC-CH as side-reaction also occured with Me3Cu2MgBr.The latter complex was prepared from MeMgBr and CuBr.The number of R groups which are transferrable from R3Cu2M to R1-CCH with an acceptable rate appeared to depend on the nature of R, viz. one R group in the case of Me3Cu2M and all three R groups in the case of Et3Cu2M.
- Westmijze, H.,Kleijn, H.,Meijer, J.,Vermeer, P.
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- Reactions of Palladium(II) with Organic Compounds. Part 5. Effect of Reaction Conditions upon Products of Oxidation of α-Methylstyrene
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The effects upon product distribution of varying the temperature, time of reaction, and reagent concentrations have been investigated in the oxidation of α-methylstyrene by palladium(II) acetate.Two reaction pathways have been identified.A ?-allylic organopalladium compound decomposes slowly in a process catalysed by excess of the alkene to give 2-phenylprop-2-enyl acetate.The second reaction leads to competitive formation of enolic acetates and oxidative dimers but the organopalladium species involved has not been unambiguously identified.The addition of sodium acetate to the reaction, contrary to earlier reports, has only a marginal effect upon the distribution of products.
- Norman, Richard O. C.,Thomas, C. Barry,Watson, Grenville
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p. 1099 - 1104
(2007/10/02)
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