- Enantioselective Ring Opening of meso-Epoxides with Silicon Tetrachloride Catalyzed by Pyridine N-Oxides Fused with the Bicyclo[3.3.1]nonane Framework
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The synthesis of new chiral Lewis basic organocatalysts that contain pyridine N-oxide moieties fused with the bicyclo[3.3.1]nonane framework is reported. The obtained pyridine N-oxides were employed as catalysts in the enantioselective ring opening of meso-epoxides with silicon tetrachloride. Derivative 1b endowed with two 2,4-diaryl-substituted pyridine N-oxide moieties proved to be a particularly effective catalyst for desymmetrization of norbornene oxide 16i to furnish Wagner-Meerwein rearrangement product 20i in unprecedented 96 % ee. Difunctional congener 3, which is striped of the 4-aryl substituents, exhibited moderate to high levels of asymmetric induction (47-88 % ee) with alicyclic epoxide substrates. Chiral Lewis basic catalysts with pyridine N-oxide moieties fused with a bicyclo[3.3.1]nonane framework were used in the enantioselective ring opening of meso-epoxides. 2,4-Diaryl-substituted N-oxide exhibited excellent asymmetric induction with norbornene oxide (96 % ee), whereas less-substituted congener was most effective with alicyclic epoxide substrates (47-88 % ee).
- Neni?kis, Algirdas,Ston?ius, Sigitas
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p. 6359 - 6369
(2015/10/06)
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- Pentamethylcyclopentadienyl ruthenium: an efficient catalyst for the redox isomerization of functionalized allylic alcohols into carbonyl compounds
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The catalytic activity of the ruthenium(II) complex [RuCp*(CH3CN)3][PF6] 1 in the transposition of allylic alcohols into carbonyl compounds, in acetonitrile, is reported. This catalyst has proven to be able to catalyze the transformation of poorly reactive and/or functionalized substrates under smooth conditions.
- Bouziane, Asmae,Carboni, Bertrand,Bruneau, Christian,Carreaux, Fran?ois,Renaud, Jean-Luc
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experimental part
p. 11745 - 11750
(2009/04/11)
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