- A NEW PRACTICAL SYNTHESIS OF SILYL ENOL ETHERS. PART.I. FROM SIMPLE ALDEHYDES AND KETONES.
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A new, practical route to enoxysilanes is described from simple enolizable aldehydes or ketones, using the trimethylchlorosilane-sodium iodide-tertiary amine reagent in acetonitrile.From certain aldehydes, an onium intermediate has been isolated.A conformational study of this onium intermediate and a thermal unimolecular syn-elimination process may explain the stereoselectivity of the reaction.Such an interpretation can be extended to all the aldehydes and ketones considered.Steric factors related to the nature both of the cabonyl derivative and of the amine play a capital role for the regio- as well as for the stereo-control of the reaction.
- Cazeau, P.,Duboudin, F.,Moulines, F.,Babot, O.,Dunogues, J.
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- New method for the synthesis of 2-aza-1,3-butadienes
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2-Aza-1,3-butadienes have been synthesized from carbonyl compounds and 1,1,1,3,3,3-hexamethyl-disilazane in the presence of cobalt-containing catalysts. The best yields (up to 95%) were achieved in the case of aldehydes branched in the α-position and 2-methylcyclohexanone. In the case of two α,β-unsaturated ketones, pyridine derivatives were found as the main products. Copyright Taylor & Francis Group, LLC.
- Sisak, Attila
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p. 3693 - 3702
(2007/10/03)
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- The regiochemistry and stereochemistry of α,β-epoxysilane ring opening with silyl halides or pseudohalides
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The reaction of trimethylsilyl halides with α,β-epoxysilanes leads to either a vinyl halide by addition/elimination or a vinyl enol ether by rearrangement; the route depends upon the nature of the groups attached to the epoxyde ring.With groups β to the silicon that can stabilise an adjacent positive charge the directive effect of silicon towards substitution at the α position is overcome such that the enol ether is obtained.Trimethylsilyl pseudohalides behave similarly except that the intermediate addition product can be isolated.The stereoselectivity of ring opening is found to vary with the reagent. epoxyde / epoxysilane / ring opening / regiochemistry / halosilane
- Bassindale, Alan R.,Soobramanien, Marie-Claire,Taylor, Peter G.
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p. 604 - 608
(2007/10/02)
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