- Potassium Base-Promoted Diastereoselective Synthesis of 1,3-Diols from Allylic Alcohols and Aldehydes through a Tandem Allylic-Isomerization/Aldol–Tishchenko Reaction
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This study reports the first base-promoted aldol–Tishchenko reactions of allylic alcohols with aldehydes initiated by allylic isomerization. The reaction enables the diastereoselective synthesis of a variety of 1,3-diols with three contiguous stereogenic centers. Unlike commonly reported systems, our method allows the use of readily available allylic alcohols as nucleophiles instead of enolizable aldehydes and ketones.
- Sai, Masahiro
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p. 4053 - 4056
(2021/10/25)
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- A simple and efficient method for the allylation of heteroarenes catalyzed by PdCl2
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The PdCl2-catalyzed allylation of heteroarenes is presented. Various heteroarenes including O-, N-, and S-based ones were allylated efficiently with a rich range of allylic acetates in the presence of only 2 mol % of PdCl2, without the need of bases/acids, additives, and external supporting ligands. In addition, the reactions were carried out under mild and simple conditions just by stirring the two reactants and catalyst in CH 2Cl2 at 60 °C. Moreover, the by-product produced was non-toxic acetic acid. Thus, the method presented in this work provides a general, clean, and operationally simple approach for the functionalization of heteroarenes. Finally, a preliminary mechanistic study suggested that the Pd(II) may be reduced in situ by the heteroarenes to Pd(0), which serves as the active metal center to catalyze the following allylations of heteroarenes via a Tsuji-Trost pathway.
- Yuan, Feng-Quan,Sun, Feng-Yi,Han, Fu-She
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scheme or table
p. 6837 - 6842
(2012/08/28)
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- Ionene-bound borohydrides: Efficient, selective, and versatile polymer-supported reducing agents
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Reduction of structurally different carbonyl compounds, such as aldehydes, ketones, α,β-unsaturated enals and enones, acid chlorides, and imines was accomplished efficiently using high capacity ionene based borohydride reagents. Aldehydes and imines were reduced to the corresponding alcohols and amines in excellent yields in methanol at ambient temperature while ketones and acid chlorides were reduced in iso-propanol and THF-MeOH at reflux. Chemoselective reduction of aldehydes over ketones was achieved successfully with these reagents. Complete regioselectivity was also observed in the reduction of α,β-unsaturated aldehydes and ketones.
- Lakouraj, Moslem M.,Tajbakhsh, Mahmood,Mahalli, Majid S.
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p. 117 - 123
(2008/09/21)
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- Organotin Nucleophiles. 5. Palladium-Catalyzed Allylic Propargylation with Allenylstannane
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Allenyltrialkylstannanes were found to react with various allylic acetates in the presence of catalytic amounts of Pd(PPh3)4 under mild neutral conditions, providing a novel approach for obtaining the 1,5-enyne carbon skeleton.The regioselectivity of propargylation depends largely on the electron-withdrawing properties of the substituents at the two ends of the allylic system: substitution occurs at the end of closer proximity to the more electronegative group.Allylic cyanohydrin acetates are substituted at a position α to the cyano group along with formation of a reduced side product.Several mechanistic aspects of these reactions are discussed.
- Keinan, Ehud,Peretz, Moshe
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p. 5302 - 5309
(2007/10/02)
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