- Copper-Catalyzed Enantioselective Conjugate Addition to α,β-Unsaturated Aldehydes with Various Organometallic Reagents
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β-Substituted aldehydes constitute a very important class of compounds found in nature. Synthesis of this motif can be envisioned by C-C bond formation on enals. For this purpose, we report herein the development of enantioselective copper-catalyzed conjugate addition of various organometallic reagents to α,β-unsaturated aldehydes with (R)-H8BINAP, (R)-TolBINAP, and (R)-SEGPHOS as chiral ligands. Three sets of conditions were successfully developed and several enals were used. Reactivity and regio- and enantioselectivities were strongly dependent on reaction conditions and substrates. Good to excellent regio- and enantioselectivities were obtained with zinc reagents R2Zn and aluminum reagents R3Al. However, the asymmetric conjugate addition of Grignard reagents afforded only moderate to good regio- and enantioselectivities.
- Goncalves-Contal, Sylvie,Gremaud, Ludovic,Palais, La?titia,Babel, Lucille,Alexakis, Alexandre
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p. 3301 - 3308
(2016/09/12)
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- Copper-catalyzed enantioselective 1,4-addition to α,β- unsaturated aldehydes
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Figure presented The first asymmetric Cu-catalyzed conjugate addition of dialkylzinc zinc reagents to a large scope of enals in presence of phosphoramidite, SimplePhos, or (R)-BINAP ligands with enantiomeric excesses up to 90% is reported. Moreover, ACA of Grignard reagents afforded moderate to good 1,4-regioselectivities with enantioselectivities up to 90%.
- Palais, Laetitia,Babel, Lucille,Quintard, Adrien,Belot, Sebastien,Alexakis, Alexandre
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supporting information; experimental part
p. 1988 - 1991
(2010/07/10)
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- Rearrangement of allylic and propargylic alcohols catalyzed by the combined use of tetrabutylammonium perrhenate(VII) and p-toluenesulfonic acid
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Allylic rearrangement and/or dehydration reaction of allylic alcohols proceeds smoothly by the use of catalytic amounts of tetrabutylammonium perrhenate and p-toluenesulfonic acid hydrate. Treatment of propargylic alcohols with the catalysts at room temperature affords the rearranged products, α,β-unsaturated carbonyl compounds, while β,γ-unsaturated ketones are obtained as main products by the reaction in refluxing 1,2-dichloroethane. The application of this catalytic system is also described for the preparation of some synthetic intermediates.
- Narasaka,Kusama,Hayashi
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p. 2059 - 2068
(2007/10/02)
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- Rearrangement of Allylic and Propargylic Alcohols Catalyzed by the Combined Use of Tetrabutylammonium Perrhenate(VII) and p-Toluenesulfonic Acid
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Allylic rearrangement and/or dehydration of allylic alcohols proceed by the use of a catalytic amount of tetrabutylammonium perrhenate and p-toluenesulfonic acid.Treatment of propargylic alcohols with the above reagents affords the rearranged products, α,β-unsaturated carbonyl compounds.
- Narasaka, Koichi,Kusama, Hiroyuki,Hayashi, Yujiro
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p. 1413 - 1416
(2007/10/02)
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- Reactions of 3-Hydroxyvinyl Selenones with Alkoxides. Oxetane Formation and Fragmentation Reactions
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3-Hydroxyvinyl phenyl selenones are prepared and their behavior as conjugate addition acceptors has been investigated.As a result, a selenonyl group has been found to activate the C=C bond for conjugate addition of nucleophiles and further to behave as an
- Shimizu, Makoto,Ando, Ryoichi,Kuwajima, Isao
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p. 1230 - 1238
(2007/10/02)
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