- Transition-metal-free arylations via photogenerated triplet 4-alkyl- and 4-trimethylsilylphenyl cations
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The irradiation in protic solvents of 4-chloroalkylbenzenes and 4-chlorophenyltrimethylsilane caused the heterolytic cleavage of aryl-chlorine bonds to give the corresponding triplet phenyl cations. These were exploited for transition-metal-free arylation reactions under mild conditions to give allylbenzenes, γ-benzyl lactones, 3-arylacetals (ketals), and biaryls in moderate to good yields. The path followed was supported by DFT calculations at the UB3LYP/6-311+G(2d,p) level.
- Qrareya, Hisham,Raviola, Carlotta,Protti, Stefano,Fagnoni, Maurizio,Albini, Angelo
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p. 6016 - 6024
(2013/07/26)
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- Chemoselective transfer of allyl or phenyl group from allyl(phenyl)germanes in Pd-catalyzed reactions with aryl halides
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Treatment of chloro(phenyl)germanes with allylmagnesium bromide yielded allyl(phenyl)germanes. Coupling of the allyl- (phenyl)germanes with aryl halides in 1,4-dioxane in the presence of aqueous NaOH and Pd catalyst resulted in Heck-type transfer of the allyl group providing the corresponding allylated aryls. On the other hand, reaction of allyl(phenyl)germanes with SbF5 intercalated in graphite in toluene and subsequent treatment of the resulting germanyl fluorides with TBAF generates reactive hypervalent fluorogermanates that undergo Stille-like Pd-catalyzed cross-coupling with aryl halides in wet toluene to provide biaryls.
- Pitteloud, Jean-Philippe,Liang, Yong,Wnuk, Stanislaw F.
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supporting information; experimental part
p. 967 - 969
(2011/12/05)
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- Palladium-catalyzed allyl cross-coupling reactions with in situ generated organoindium reagents
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Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions, using allylindium generated in situ from allyl halides and indium, is demonstrated. Allylindium compounds may be effective nucleophilic coupling partners in palladium-catalyzed cross-coupling reactions. A variety of allyl halides, such as allyl iodide, allyl bromide, crotyl bromide, prenyl bromide, geranyl bromide, and 3-bromocyclohexene afforded the allylic cross-coupling products in good to excellent yields. Stereochemistry of the double bond is retained in the allylic cross-coupling reactions. Electrophilic cross-coupling partners, such as aryl and vinyl halides, dibromoolefin, alkynyl iodide, and aryl and vinyl triflates participate in these reactions. The presence of various substituents, such as n-butyl, ketal, acetyl, ethoxycarbonyl, nitrile, N-phenylamido, nitro, and chloride groups on the aromatic ring of electrophilic coupling partners showed little effect on the efficiency of the reactions. The present conditions work equally well for not only intermolecular but also intramolecular palladium-catalyzed cross-coupling reactions. These methods provide an efficient synthetic method for the introduction of an allyl group, which can be easily further functionalized to afford an sp2- and sp-hybridized carbon. The present method complements existing synthetic methods as a result of advantageous features such as easy preparation and handling, thermal stability, high reactivity and selectivity, operational simplicity, and low toxicity of allylindium reagents.
- Lee, Kooyeon,Kim, Hyunseok,Mo, Juntae,Lee, Phil Ho
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scheme or table
p. 2147 - 2157
(2011/10/31)
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- Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions using allylindium generated in situ from allyl acetates, indium, and indium trichloride
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Inter- and intramolecular palladium-catalyzed ally! cross-coupling reactions using allylindium generated in situ by treatment of allyl acetates with indium and indium trichloride in the presence of Pd0 catalyst and nBuNMe2 in DMF were successfully demonstrated. Allylindium species generated in situ by reductive transmetalation of π- allylpalladium(II) complexes, obtained from a variety of allyl acetales in the presence of Pd0 catalyst together with indium and indium trichloride, were found to be capable of acting as effective nucleophilic coupling partners in Pd-catalyzed cross-coupling reactions. A variety of allyl acetates such as but-l-en-3-yl acetate, crotyl acetate, and 2-methylallyl acetate afforded the corresponding allylic compounds in good yields in cross-coupling reactions. Various electrophilic cross-coupling partners such as aryl iodides and vinyl bromides and triflates participate in these reactions. Not only intermolecular but also intramolecular Pd-catalyzed cross-coupling reactions work equally well to produce the desired allylic coupling products in good yields.
- Seomoon, Dong,Lee, Kooyeon,Kim, Hyunseok,Lee, Phil Ho
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p. 5197 - 5206
(2008/02/10)
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- Palladium-indium-indium(III) chloride-mediated allyl cross-coupling reactions using allyl acetates
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Allylindiums in situ generated by reductive transmetalation of π-allylpalladium(II) complexes, obtained from allyl acetates and palladium(0) catalyst, with indium and indium(III) chloride are effective nucleophilic cross-coupling partners in Pd-catalyzed allyl cross-coupling reactions with a variety of electrophilic cross-coupling partners.
- Lee, Phil Ho,Seomoon, Dong,Lee, Kooyeon,Kim, Sundae,Kim, Hyunseok,Kim, Hyun,Shim, Eunkyong,Lee, Miae,Lee, Seokju,Kim, Misook,Sridhar, Madabhushi
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p. 1641 - 1645
(2007/10/03)
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