- ELECTROPHILIC SUBSTITUTION OF STRUCTURALLY RIGID n1-ALLYLPALLADIUM COMPLEXES
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h1-Allyl(aryl)palladium complexes react with some electrophiles to result in the selective Pd-allyl bond cleavage with 1,3-transposition, while the corresponding η3-allyl(aryl)palladiums and the electrophiles give rise to the selective Pd-Ar bond cleavage.The η1-allyl complexes also react with CCl4 and CHCl3 under very mild conditions to give good yields of CH2=CHCHR(CR'Cl2) (R=H, Me; R'=Cl, H).
- Kurosawa, Hideo,Urabe, Akira
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- A mild method for the replacement of a hydroxyl group by halogen: 3. the dichotomous behavior of α-haloenamines towards allylic and propargylic alcohols
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A study of the deoxyhalogenation of allylic and propargylic alcohols with tetramethyl-α-halo-enamines is reported. Primary allylic and primary and secondary propargylic alcohols gave the corresponding halides in high yields. Secondary allylic and propargylic alcohols yielded the corresponding secondary halides but the reaction also produced some rearranged primary halides (I > Br > Cl). The reactions with tertiary allylic and tertiary propargylic alcohols gave several products and was therefore of little synthetic value. However, the addition of triethylamine to the reaction mixture or the use of lithium alkoxide instead of alcohol brought about a major change of the course of the reaction which led to amides carrying an allyl or an allenyl group at C2. This was shown to result from a Claisen-Eschenmoser rearrangement of an intermediate α-allyloxy- or propargyloxy-enamine.
- Munyemana, Fran?ois,Patiny, Luc,Ghosez, Léon
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- Heterogeneous fluorination of allylic halides by the combination of lead fluoride and a sodium salt
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The composite solid reagent consisting of lead(II) fluoride and a small amount of sodium bromide has been found to facilitate the fluorination of allylic halides in acetonitrile to afford a mixture of the corresponding and rearranged fluorides in the ratio of 1:1 to 1:2.Such allylic rearrangement is not observed when KF/18-crown-6 or tetrabutylammonium fluoride are employed. - Keywords: Heterogeneous fluorination; Allylic halides; Lead fluoride; Sodium salts; NMR spectroscopy
- Ichihara, Junko,Takai, Yoshio,Hanafusa, Terukiyo,Tomioka, Kiyoshi
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p. 131 - 134
(2007/10/02)
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- SYNTHESIS OF ALKYL HALIDES UNDER NEUTRAL CONDITIONS
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Primary and secondary alcohols are efficiently converted to the corresponding alkyl halides under neutral conditions.
- Munyemana, Francois,Frisque-Hesbain, Anne-Marie,Devos, Alain,Ghosez, Leon
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p. 3077 - 3080
(2007/10/02)
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- Isolation of the First Allylic Gold(III) Complex Having a Triphenylphosphine Ligand
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A metathetical reaction of cis-dimethyliodo(triphenylphosphine)gold(III) with 1-methylallyl Grignard reagent in ether at 0 deg C gives cis-dimethyl(η1-E-crotyl)(triphenylphosphine)gold(III), 1.Reactions of 1 with HCl and bromine give selectively 1-butene and 1-methylallyl bromide, respectively.
- Komiya, Sanshiro,Ozaki, Satoshi
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p. 1431 - 1432
(2007/10/02)
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- CONVERSION OF ALCOHOLS INTO ALKYL BROMIDES AND IODINES VIA O-ALKYLISOUREAS
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Treatment of O-alkylisoureas with trifluoromethanesulphonic acid and a tetrabutylammonium salt (bromide or iodide) affords alkyl halides in high yields.
- Collingwood, Stephen P,Davies, Alan P,Golding, Bernard T
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p. 4445 - 4448
(2007/10/02)
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- BORON TRIFLUORIDE ETHERATE/HALIDE ION, A NOVEL REAGENT FOR THE CONVERSION OF ALLYL, BENZYL AND TERTIARY ALCOHOLS TO THE HALIDES
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A combination of boron trifluoride etherate and halide ion is found to be an excellent reagent for the conversion of allyl, benzyl and tertiary alcohols to the halides.
- Mandal, Arun K.,Mahajan, S. W.
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p. 3863 - 3866
(2007/10/02)
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- A reinvestigation of the vapor phase bromination of 2-bromobutane
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The soltuion phase photobromination of 2-bromobutane yields 2,2-dibromobutane, meso-2,3-dibromobutane, dl-2,3-dibromo-dibromobutane, small amounts of 1,2-dibromobutane, and 2,2,3-tribromobutane.However, in the corresponding vapor phase bromination these products appear along with other polybrominated products.The yield of these polybromides increases with temperature.The increase in yield of the polyhalogenated materials is rationalized by considering the thermal instabilty of the β-bromoalkyl radical, which eliminates a bromine atom to form the corresponding alkene.It is demonstrated that in the vapor phase allylic bromination competes succesfully with bromine addition.Reaction schemes are suggested to explain the formation of polybromides.An explanation is also offered for the dicrepancy between these results and those of previously reported vapor phase work.
- Tanner, Dennis D.,Ruo, Tomoki C. S.,Kosugi, Yoshio,Potter, Alan
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p. 2310 - 2316
(2007/10/02)
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- Interhalogen-Catalyzed Cleavages of Ethers and Esters with Trimethylsilyl Bromide or Chloride
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The cleavages of various dialkyl ethers, trimethylsilyl alkyl ethers, and alkyl esters by trimethylsilyl bromide are strongly catalyzed by iodine monobromide.This catalyzed cleavage procedure using iodine monobromide makes possible synthetic applications for trimethylsilyl bromide which were previously ruled out by problems with its low reactivity.Cleavages of benzylic and tertiary alkyl ethers and esters by trimethylsilyl chloride are feasible when catalyzed by iodine monochloride.However, other systems are essentially unreactive toward trimethylsilyl chloride even in the presence of iodine monochloride.
- Friedrich, Edwin C.,DeLucca, George
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p. 1678 - 1682
(2007/10/02)
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