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Carbonyl bromide fluoride alcohols

Fluoroformic esters are obtained either from the corresponding chloroformates and thallium fluoride by halogen exchange859 or, if the expensive T1F is not available, from carbonyl bromide fluoride and alcohols which give only... [Pg.214]

Fluoride ion is effective in promoting the reduction of aldehydes by organosil-icon hydrides (Eq. 161). The source of fluoride ion is important to the efficiency of reduction. Triethylsilane reduces benzaldehyde to triethylbenzyloxysilane in 36% yield within 10-12 hours in anhydrous acetonitrile solvent at room temperature when tetraethylammonium fluoride (TEAF) is used as the fluoride ion source and in 96% yield when cesium fluoride is used.83 The carbonyl functions of both p-anisaldehyde and cinnamaldehyde are reduced under similar conditions. Potassium bromide or chloride, or tetramethylammonium bromide or chloride are not effective at promoting similar behavior under these reaction conditions.83 Moderate yields of alcohols are obtained by the KF-catalyzed PMHS, (EtO SiH, or Me(EtO)2SiH reduction of aldehydes.80,83,79... [Pg.59]

Tris(dimethylamino)sulfonium difluo-rotrimethylsilicate, 336 Xenon(II) fluoride, 345 Alkyl bromides Potassium permanganate, 258 Sodium bromide, 46 Tetraethylammonium bromide, 46 Alkyl iodides Aluminum iodide, 17 Potassium permanganate, 258 Sodium iodide, 46 Tetraethylammonium iodide, 46 Alkynes (see also Acetylenic carbonyl compounds, Diynes, Enynes, Propar-gyl alcohols)... [Pg.382]

Bu3Bi mediates the allylation of carbonyl compounds with allyl bromide to give a mixture of homoallyl alcohols and fheir allyl ethers (Scheme 14.133) [278], Tris(4-methoxyphenyl)bismuthane catalyzes the cyanation of carbonyl compounds with MesSiCN [175], In the presence of fluoride ions (CeFsjsBi undergoes nucleophilic substitution with an activated C-F bond of perfluorinated compounds to transfer three CgFj groups [279]. (CFsjsBi can also act as a trifluoromethyl anion equivalent [280]. [Pg.790]

Diaryliodonium salts react more or less easily with carbonyl compounds to afford the C-arylated derivatives. Depending upon the nature of the substrate, different experimental conditions have been used. These reactions are generally performed in alcoholic solvents (r-BuOH, r-AmOH.) or in DMF, at temperatures ranging from low (- 78°C) to reflux of the solvent. Arylation of simple ketones has been obtained either by reaction of the ketone enolates with an appropriate diaryliodonium salt, i or by reaction of the ketone enol silyl ether with diaryliodonium fluoride. Phenylation of the potassium enolate of acetone (13) with diphenyliodonium bromide (14) afforded a modest yield of the monophenylation product, but the stimulation with solvated electrons led to overreaction due to the subsequent reaction of the iodobenzene, a good SrnI arylating agent under these conditions. 9... [Pg.110]

Allylsilane and Propargylsilane Synthesis. (lodomethyl)-trimethylsilane has been used to prepare aflylsUanes, which are t)q)icafly utilized in Lewis acid or fluoride ion-promoted reactions with carbonyl compounds to provide homoallylic alcohols. Treatment of Mc3SiCH2l with methyltriphenylphosphonium bromide and base produces an intermediate phosphonium salt which can be further utilized to prepare allylsilanes from carbonyl compounds. This procedure has been modified so that this series of transformations can be done as a one-pot procedure (eq 1). ... [Pg.323]

Non-fluoride initiators have been employed satisfactorily as well, including Lewis bases (amines, amine A-oxides, carbonates and phosphates," LiOAc," " f-BusF ), Lewis acids," A-heterocyclic carbenes, or even without initiator in DMSO as solvent. The addition of TMSCF3 to carbonyl compounds in the presence of a chiral initiator allows the enantioselective preparation of trifluoromethyl alcohols. For this purpose, quaternary ammonium fluorides derived from cinchona alkaloids (1) have been employed, affording moderate (up to 51% ee) " to high enantioselectivities (up to 92% ee). Also, the corresponding bromides were used in combination with an external fluoride source (KF or TMAF, up to 94% ee) or with disodium (R)-binaphtholate (up to 71% ee), or simply a cinchonidine-derived ammoniumphenoxide (up to 87% ee). Moreover, the use of a chiral TASF derivative (2) has also been reported (up to 52% ee). ... [Pg.541]


See other pages where Carbonyl bromide fluoride alcohols is mentioned: [Pg.1236]    [Pg.526]    [Pg.221]    [Pg.961]    [Pg.54]    [Pg.148]    [Pg.959]    [Pg.166]    [Pg.305]    [Pg.1274]   
See also in sourсe #XX -- [ Pg.734 ]




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Alcohols carbonylation

Alcohols carbonylations

Bromides alcohols

Bromides carbonylation

Carbonyl bromide

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