Ketone alkyl aryl ketones

The Schmidt reaction of ketones works best with aliphatic and alicyclic ketones alkyl aryl ketones and diaryl ketones are considerably less reactive. The reaction is only seldom applied to aldehydes as starting materials. The hydrazoic acid used as reagent is usually prepared in situ by treatment of sodium azide with sulfuric acid. Hydrazoic acid is highly toxic, and can detonate upon contact with hot laboratory equipment. 

Bis[4-methoxyphenyl] dicyanomethylidene tellurium did not react with benzaldehyde3. Dibutyl ethoxyearbonylmethylidene tellurium and aliphatic aldehydes, aromatic aldehydes, cycloalkanones, dialkyl ketones, alkyl aryl ketones, and diphenyl ketone combine to yield a,/ -unsa turated carboxylic acid esters predominantly in the ( )-form4. Dibutyl cyanomethylidene and dibutyl benzoylmethylidene tellurium react similarly with benzal-dehydes and ketones5. 

The mixed hydride is the reagent of choice for the reduction of diaryl ketones, alkyl aryl ketones, and certain aryl alcohols to the corresponding hydrocarbons. Usually best yields are obtained if an equimolecular mixture of the ketone and aluminum chloride in ether is added to the I 1 LiAlHj AICI3 reagent. 

Aldehydes generally undergo this reaction faster and more completely than ketones. Alkyl aryl ketones give only poor yields of cyanohydrin, and diaryl ketones give none at all. 

Claisen-Schmidt reaction. Aromatic aldehydes condense with aliphatic or mixed alkyl-aryl ketones in the presence of aqueous alkali to form ap-unsaturated ketones ... 

In the alkyl aryl ketones, the aryl groups migrate preferentially, yielding V-aryl amides. 

When an alkyl aryl ketone is heated with yellow ammonium polysulphide solution at an elevated temperature, an aryl substituted aliphatic acid amide is foimed the product actually isolated is the amide of the ci-aryl carboxylic acid together with a smaller amount of the corresponding ammonium salt of the oarboxylio acid. Thus acetophenone affords phenylacetamide (50 per cent.) and ammonium phenylacetate (13 per cent.) ... 

Acylation (Sections 16.3,21.4) The introduction of an acyl group, —COR, onto a molecule. For example, acylation of an alcohol yields an ester, acylation of an amine yields an amide, and acylation of an aromatic ring yields an alkyl aryl ketone. 

Der Komplex aus Lithiumalanat, (-)- bzw. (+)-N-Methyl-ephedrin und 3,5-Dime-thyl-phenol reduziert unverzweigte Alkyl-aryl-ketone in Ausbeuten iiber 90% und optischen Ausbeuten von 62 bis 80% zu den (+)-(R)- bzw. (-) -(S)-1 -Phenyl-alka-nolen . 

With alkyl aryl ketones, it is the aryl group that generally migrates to the nitrogen, except when the alkyl group is bulky. The reaction has been applied to a few aldehydes, but rarely. With aldehydes the product is usually the nitrile (16-21). Even with ketones, conversion to the nitrile is often a side reaction, especially with the type of ketone that gives 17-31. A useful variation of the Schmidt reaction treats a cyclic ketone with an alkyl azide (RN3) in the presence of TiCU, generating a... 

Alkyl aryl ketones can be converted to arylacetic acid derivatives in an entirely different manner. The reaction consists of treatment of the substrate with silver nitrate and I2 or Br2, ° or with thallium nitrate, MeOH, and trimethyl orthoformate adsorbed on Montmorillonite K-10 clay, an acidic clay. ... 

In addition, Peruzzini et al. developed, in 2007, iridium complexes of planar-chiral ferrocenyl phosphine-thioether ligands that were tested in the hydrogenation of simple alkyl aryl ketones.These complexes were diastereoselec-tively generated in high yields (85-90%) by addition of the corresponding... 

Scheme 8.33 Hydrogenations of alkyl aryl ketones with ferrocenyl phosphine-thioether ligands.

Smith, R. M. and Finn, N., Comparison of retention index scales based on alkyl aryl ketones, alkan-2-ones and 1-nitroalkanes for polar drugs on re-versed-phase high-performance liquid chromatography,. Chromatogr., 537, 51,1991. 

Amalgamated zinc residues isolated from Clemmensen reduction of an alkyl aryl ketone in glacial acetic acid were pyrophoric, and had to be immediately dumped into water after filtration to prevent ignition. 

Treatment of a-(benzotriazol-l-yl)alkyl thioethers 831 with ZnBr2 weakens the bond with benzotriazole, and the obtained complex 832 may partially dissociate to thionium cation 835 that can be trapped by even mild nucleophiles. Thus, trimethylsilyl cyanide added to the reaction mixture causes substitution of the benzotriazole moiety by the CN group to give a-(phenylthio)carbonitrile 834. In a similar manner, treatment with allylsilane leads to y,S-unsaturated thioether 833. Addition of species 835 to the double bond of a trimethylsilyl ot-arylvinyl ether followed by hydrolysis of the silyloxy group furnishes (i-(phenylthio)alkyl aryl ketones 836 (Scheme 132) <1996TL6631>. 

It is well accepted that the asymmetric reduction of simple dialkyl ketones generally proceeds with low enantioselectivity.68 Ohkuma et al.69 reported that hydrogenation of simple ketones can be achieved using Ru(II) catalysts in the presence of diamine and alcoholic KOH in 2-propanol. Promising results have been achieved in the asymmetric hydrogenation of alkyl aryl ketones with a mixture of an Ru-BINAP complex, chiral diamine, and KOH (Scheme 6-33). 

The quininium and quinidinium fluoride catalysts, 10 (R=H etc., X=F) and 8 (R=H, X=F), were used for the asymmetric reduction of alkyl aryl ketones in conjunction with silanes.1751 One of the most efficient silanes proved to be tris(trimethylsiloxy)silane, which together with 8 (R=H, X=F) reduced acetophenone to give the alcohol 102 in almost quantitative yield with 78 % ee, as shown in Scheme 31. The... 

Scheme 31. Asymmetric reduction of alkyl aryl ketones.

Asymmetric reductions. The reagent can effect asymmetric reduction of alkyl aryl ketones and unhindered dialkyl ketones in high optical yield.1 It is the most useful reagent known to date for asymmetric reduction of even hindered a-keto esters to (S)-a-hydroxy esters in >90% ee.2 It is also effective for asymmetric reduction of phosphinyl imines of dialkyl ketones, RlR2C=NP(0)(C6H5)2 (50-84% ee).3... 

Enantioselective reduction of ketones.1 The ability of diborane in combination with the vic-amino alcohol (S)-2-amino-3-methyl-l,l-diphenyl-l-butanol (12, 31) to effect enantioselective reduction of alkyl aryl ketones involves formation of an intermediate chiral oxazaborolidine, which can be isolated and used as a catalyst for enantioselective borane reductions (equation I). 

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