- Lewis Acid Induced Rearrangement of 1-Hetero-2,3-Epoxides. Synthesis, Reactivity and Synthetic Applications of Homochiral Thiiranium and Aziridinium Ion Intermediates
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2,3-Epoxy sulfides and 2,3-epoxy amines, prepared in an optically active form via the Sharpless asymmetric epoxidation, both undergo a Lewis acid induced rearrangement to give the corresponding thiiranium and aziridinium ions respectively. These reactive intermediates, generated in situ, react efficiently with a variety of nucleophiles such as silylated aromatic heterocycles, amides, and amines, including amino acid derivatives. Imines can be used as synthetic equivalents of primary amine nucleophiles, which effectively allows selective monoalkylation with a reactive thiiranium ion intermediate. Applications of this new methodology, and mechanistic studies are also discussed.
- Rayner, Christopher M.
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- Homochiral 2,3-epoxy sulfides - powerful new synthetic building blocks providing stereoselective access to 2,3-epoxy sulfoxides, 2,3-dihydroxy sulfoxides and (E)-γ-hydroxy-α,β-unsaturated sulfoxides and sulfones. X-Ray molecular structure of rac-(2R*,3R*)-1-...
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The stereoselective transformation of homochiral 2,3-epoxy sulfoxides into 2,3-epoxy sulfoxides is described.These intermediates undergo elimination under basic reaction conditions to give (E)-γ-hydroxy-α,β-unsaturated sulfoxides, and under Lewis acidic conditions form novel cyclic sulfoxonium salts which on hydrolysis give 2,3-dihydroxy sulfoxides with excellent stereochemical control. 2,3-Dihydroxy sulfoxides can also be converted into (E)-γ-hydroxy-α,β-unsaturated sulfoxides by elimination via cyclic sulfide.The synthesis of (E)-γ-hydroxy-α,β-unsaturated sulfones by base-catalysed elimination of a 2,3-epoxy sulfone is also described.
- Westwell, Andrew D.,Thornton-Pett, Mark,Rayner, Christopher M.
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p. 847 - 860
(2007/10/02)
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- Stereoselective synthesis of 2,3-epoxy sulphoxides
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Methods for the diastereoselective preparation of various 2,3-epoxy sulphoxides are described using a double enantioselective oxidation approach. Direct comparisons of the selectivity and efficiency of the Davis and Kagan asymmetric sulphur oxidation procedures are given.
- Rayner,Sin,Westwell
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p. 7237 - 7240
(2007/10/02)
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