- One-pot synthesis of 3-hydroxymaleic anhydrides by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride
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Functionalized 3-hydroxymaleic anhydrides were prepared by cyclization of 1,1-bis(trimethylsilyloxy)ketene acetals with oxalyl chloride.
- Rotzoll, Sven,Ullah, Ehsan,G?rls, Helmar,Fischer, Christine,Langer, Peter
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p. 2647 - 2656
(2007/10/03)
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- Photooxygenation of Silyl Ketene Acetals: Dioxetanes as Precursors to α-Silylperoxy Esters in the Silatropic Ene Reaction
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Photooxygenation of silyl ketene acetals afforded dioxetanes, which subsequently underwent secondary reactions to give rearrangement products (α-silylperoxy esters, major products) and cleavage products (pivalaldehyde, minor product).The kinetics of these reactions were studied by NMR and chemiluminescence.The activation energy of the chemiluminescence cleavage process was 2-3 kcal/mol higher than that of the rearrangement.In the presence of catalytic amounts of CF3COCF3 or CF3COCH3, the (E)-silyl ketene acetals rearranged into their Z isomers.Photooxygenation of the (E)- and (Z)-silyl ketene acetals showed that the cycloaddition was rigorously diastereoselective.Trapping experiments with acetaldehyde confirmed the intermediacy of 1,4-zwitterions in the rearrangement of the (E)- and (Z)-dioxetanes into α-silylperoxy esters, but such intermediates were not detected during the photooxygenation of the silyl ketene acetals; the latter proceeds presumably via perepoxides.
- Adam, Waldemar,Wang, Xiaoheng
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p. 4737 - 4741
(2007/10/02)
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- α-SILYL TRIMETHYLSILYLESTERS FROM ALIPHATIC CARBOXYLIC ACID DIANIONS
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The synthesis of α-silyl trimethylsilyl esters from aliphatic carboxylic acid dianions is reported.The results indicate kinetic and thermodynamic control of silylation of acid dianions.
- Bellassoued, M.,Dubois, J. E.,Bertounesque, E.
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p. 263 - 266
(2007/10/02)
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