- Cobalt- and rhodium-catalyzed cross-coupling reaction of allylic ethers and halides with organometallic reagents
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Reactions of 2-alkenyl methyl ether with phenyl, trimethylsilylmethyl, and allyl Grignard reagents in the presence of cobalt(II) complexes are discussed. The success of the reactions heavily depends on the combination of the substrate, ligand, and Grignard reagent. In the reaction of cinnamyl methyl ether, the formation of the linear coupling products predominates over that of the relevant branched products. In the cobalt-catalyzed allylation of allylic ethers, addition of a diphosphine ligand can change the regioselectivity, mainly providing the corresponding branched products. Rhodium complexes catalyze the reactions of allylic ethers and halides with allylmagnesium chloride and allylzinc bromide, respectively, in which the branched coupling product is the major product.
- Yasui, Hiroto,Mizutani, Keiya,Yorimitsu, Hideki,Oshima, Koichiro
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p. 1410 - 1415
(2007/10/03)
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- Nickel-Catalyzed Arylation of Acrolein Diethyl Acetal: A Substitute to the 1,4-Addition of Arylhalides to Acrolein
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(Equation presented) In the presence of catalytic amount of NIBr 2 as catalyst precursor, organic halides are reductively coupled at 70°C with acrolein diethyl acetal to give (Z)- and (E)-enolethers by allylic deplacement of an alkoxy group. Subsequent hydrolysis affords β-arylated aldehydes.
- Condon,Dupre,Nedelec
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p. 4701 - 4703
(2007/10/03)
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- Alkylation of 2-Oxy-Substituted 1-Sulfonylallyl and 1-Sulfonylvinyl Anions. New Routes to Functionalized Carbocycles and Dihydrofurans
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Alkylation of the anion derived from 2-phenoxy-3-(phenylsulfonyl)-1-propene proceeds α to the phenylsulfonyl group and affords cyclic products from 1,ω-dihalides.Reaction of the monoalkylated products, in which a suitably positioned olefinic or acetylenic unit is present, with sodium benzenesulfinate-acetic acid gives functionalized acetylcyclopentenes and cyclohexenes via C-C bond formation from the allyl cation-sulfinate ion pair.In the vinyl sulfone series, deprotonation of (E)- or (Z)-2-alkoxyvinyl phenyl sulfones rapidly affords the more stable (E)-lithio derivative, an acetaldehyde anion equivalent which reacts normally with aldehydes, ketones, alkyl halides, and epoxides.The latter process may be effected in an intramolecular fashion.Thus, (E)-(2-phenylsulfonyl)vinyl ethers of 2,3-epoxy alcohols cyclize on treatment with amide bases to afford dihydrofurans whose stereochemistry is fully defined by that of the starting epoxy alcohol.
- Padwa, Albert,Bullock, William H.,Dyszlewski, Andrew D.,McCombie, S. W.,Shankar, B. B.,Ganguly, A. K.
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p. 3556 - 3564
(2007/10/02)
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- CONFIGURATIONAL PROPERTIES AND CHEMICAL REACTIVITY OF MONO AND DIANIONS DERIVED FROM ARYL 2-ALKOXYVINYL SULFONES
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E-2-Alkoxy-1-arylsulfonylethenes are regio and stereospecifically lithiated at C-1 and the resulting species react efficiently with a variety of electrophiles to give synthetically useful products.
- McCombie, S. W.,Shankar, B. B.,Ganguly, A. K.,Padwa, Albert,Bullock, William H.,Dyszlewski, Andrew D.
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p. 4127 - 4130
(2007/10/02)
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