- Selective electrosynthesis of (trimethylsilyldifluoro)methylbenzene, a PhCF2-precursor; conditions for a molar scale preparation without HMPA
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Electrochemical reductive silylation of trifluoromethylbenzene by the sacrificial anode technique selectively led, in a THF/DMPU mixture instead of THF/HMPA and according to the charge passed, to the corresponding mono-, bis- or tris-trimethylsilyl derivatives, respectively PhCF2TMS, PhCF(TMS)2 and PhC(TMS)3. This reaction, without any chemical equivalent, was extended to a molar scale synthesis, using a tubular flow cell.
- Clavel,Léger-Lambert,Biran,Serein-Spirau,Bordeau,Roques,Marzouk
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The sacrificial anode electrochemical technique, using an undivided cell and a constant current density, provides a nice preparative route for creating Si-Si and C-Si bonds without using alkali metals. Compared to the chemical organometallic synthesis, this method is extremely selective and can lead to original compounds not accessible by the chemical routes. Bases, such as the 2-pyrrolidone magnesium salt electrogenerated in the same conditions, allowed the stereoselective synthesis of Z-silyl enol ethers. Finally, the reduction potentials of a large number of chlorosilanes measured by cyclic voltammetry in standard conditions are reported.
- Biran,Bordeau,Bonafoux,Deffieux,Duprat,Jouikov,Leger-Lambert,Moreau,Serein-Spirau
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p. 591 - 600
(2007/10/03)
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- Polychlorinated materials as a source of polyanionic synthons
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The reaction of dichloromethane (1a) or dichlorodideuteriomethane (1b) with an excess of lithium powder (1:7 molar ratio) and a catalytic amount of DTBB (5 mol%) in the presence of a carbonyl compound 2 (1:2 molar ratio) in THF at -40°C yields, after hydrolysis, the corresponding 1,3-diols 3 in moderate yields. The process is applied to other gem-dichlorinated materials such as 7,7-dichloro [4.1.0]heptane (4), 1,1-dichlorotetramethylcyclopropane (7) and dichloromethyl methyl ether (10), using pivalaldehyde as electrophile. Starting from 1,1,1-trichlorinated compounds or tetrachloromethane (14) and using chlorotrimethylsilane as electrophile at temperatures ranging between -80 and -90°C, the corresponding polysilylated compounds 15-17 are prepared applying the mentioned methodology.
- Guijarro, Albert,Yus, Miguel
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p. 1797 - 1810
(2007/10/03)
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