Ketone To alkene

AICI3 is a moisture-sensitive and strong Lewis acid. It is a first choice for Friedel-Crafts-type reactions, which provide numerous important transformations in laboratory and industry. It can also be applied to the transformation of alkenes to ketones via alkylaluminum halides.303 Hydrozirconation of an olefin and subsequent transmetalation from zirconium to aluminum gives the corresponding alkylaluminum dichloride, and the subsequent acetylation by acetyl chloride affords the corresponding ketone in high yield (Scheme 66). 

Pd poly(benz-imidazole) nitrile oxidation of alkenes to ketones [96]... 

Oxidation of alkenes to ketones.3 Both internal and terminal alkenes are oxidized by PdCl2 (with CuCl2 as reoxidant) in water-polyethylene glycol (PEG), serving as the phase-transfer catalyst as well as the solvent (9, 360, 376). This oxidation is more facile than that catalyzed by quaternary ammonium salts, which is applicable only to terminal alkenes. 

The synthetic applications of the palladium-catalyzed oxidation of alkenes to ketones have recently been reviewed.639 Improvements in the Wacker palladium-catalyzed ketonization of terminal alkenes have been obtained using phase-transfer catalysis,641 polyethylene glycol642 or phosphomolybdovanadic acids.643... 

Ketones from halohydrins. Palladium acetate complexed with a triarylphos-phine, particularly tri-o-tolylphosphine, converts halohydrins into ketones in the presence of K2C03. Yields are about 70-85% for substrates in which the halogen is secondary or tertiary, but less than 50% when the halogen is primary because of epoxide formation. The reaction is useful for conversion of alkenes to ketones in those instances in which halohydrins are formed regioselectively. 

Oxidation of alkenes to ketones. This palladium complex is an effective catalyst for air oxidation of 1-alkenes to methyl ketones in high yield via a nitro-nitrosyl redox couple. ... 

Aqueous chromic acid has been used to oxidize alkylboranes derived from cyclic alkenes to ketones. For example, hydroboration and oxidation of 1-methylcyclohexene converts it into 2-methylcyclohexanone (Equation B2.10). 

Palladium catalysts are best known for oxidizing alkenes to ketones or vinyl derivatives. However, formation of a, unsaturated carbonyl compounds by UV irradiation of oxygenated solutions of alkoies in the presence of catalytic amounts of palladium s ts has been observed by Muzait - This reaction is believed to proceed through a ir-allylpalladium trifluoroacetate complex, e.g. (77). 

The oxidation of (secondary alkyl)boranes with chromic acid leads to ketones, " and in combination with hydroboration provides a high-yielding route from alkenes to ketones. The reaction gives ketones at... 

Other retrocycloadditions may occur in the decomposition of /3-sultines, obtained by reaction of triplet sulfur dioxide with alkenes, to ketones and sulfines (or a carbene and sulfur monoxide) and in the decomposition of 1,2-oxathietane-4-one 2-oxides to carbon dioxide and a sulfine. The mass spectrum of 1,2-oxathietane 2-oxide shows a fragment attributed to sulfine. ... 

Oxidations with chromic oxide encompass hydroxylation of methylene [544] and methine [544, 545, 546] groups conversion of methyl groups into formyl groups [539, 547, 548, 549] or carboxylic groups [550, 55i] and of methylene groups into carbonyls [275, 552, 553, 554, 555] oxidation of aromatic hydrocarbons [556, 557, 555] and phenols [559] to quinones, of primary halides to aldehydes [540], and of secondary halides to ketones [560, 561] epoxidation of alkenes [562, 563,564, and oxidation of alkenes to ketones [565, 566] and to carboxylic acids [567, 565, 569]. 

To conclude this study, we examined the possibility of recycling and reusing the HY catalyst. Initially, the spent solid was simply recovered by filtration, washed with acetone, dried at 110°C, and reused. Under these conditions, the recycled aluminosilicate exhibited only poor catalytic activity, and the conversion of the alkene to ketone was limited to a few per-cent. en an additional calcination step was performed before reuse, on the other hand, the recycled material was almost as active as a fresh sample of zeolite HY. For instance, the yield of (2) dropped only from 45 to 39% when catalyst regenerated by calcination in air at 400°C was used instead of the original fresh molecular sieve. Furthermore, it was possible to reemploy the same catalyst in a third, and even a fourth run, without any further decrease in yield, provided that the solid was regenerated by calcination between each successive reaction. 

Diols are oxidatively cleaved to ketones and/or aldehydes by periodic acid (HIO4). Ozonolysis oxidatively cleaves alkenes to ketones and/or aldehydes when worked up under reducing conditions and to ketones and/or carboxylic acids when worked up under oxidizing conditions. Acidic solutions and hot basic solutions of potassium permanganate also oxidatively cleave alkenes to ketones and/or carboxylic acids. 

The functional group transforms for the alkene to ketone conversion are ... 

The //4-0X0 cluster [Pd6Cu4Cli204(HMPA)4] catalyzes the oxidation of alkenes to ketones by 02. Oxidation of cyclohexene to a mixture of cyclohexanone and cyclohexenone (88 12) was achieved in 360% yield by use of the polymeric complex [ClCuL4(/i-Cl)PdCl2 PdCl2] (L = pyrrolidin-2-one) as catalyst. ... 

Attack of the oxygen atom of NO2 anion at Pd-coordinated alkene ligand afforded metallacycle compounds (Scheme 8.32) [53]. The X-ray structure determination of the product from dicylopentadiene complex of Pd(II) established the cis oxypalladation. The metallacycle thus formed can be regarded as an intermediate in Pd-catalyzed oxidation of alkenes to ketones or epoxides with the use of NO2 ligand as a mediator and O2 as an oxidant. 

Oxone in conjunction with OsOq cleaves alkenes to ketones or carboxylic acids (eq 43). This protocol has the advantage over traditional methods in that there is no need for intermediate... 

The O -oxidation of alkenes to ketones can also be effected by cationic palladium nitro complexes like [(CH2CN)2Pd(N02)ICl, containing both the 0-donor NO group and the alkene activating Lewis acid center... 

The oxidation of alkenes to ketones can occur by routes other than hydroxy-metallation. Oct-1-ene is converted into octan-2-one using [Rh(Oa)(AsPh3)4]-CIO4 and using 70% enriched 0 in the complex there is 70% in the octan-2-one, which is accounted for by the mechanism in Scheme 18. Similar conclusions are made from a related study using [RhCl(PPh3)3]. ... 

An oxametallacyclic intermediate has been suggested for the oxidation of alkenes to ketones on an oxygenated Rh(l 11) surface.3l3.3l4 Theoretical calculations on the oxidative addition of CH4 to second row metal atoms predict that this will be most favourable for Rh.3l5 The exothermicity of the addition of CH4 to Rh(I) can be improved by the presence of a ligand, but its position (in or out of the RhCH plane) is crucial.316... 

Figure 10. Catalytic oxygenation of alkenes to ketones or epoxides.

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