Alkyl-aryl ketone arylation

The synthesis will therefore normally produce a 2,4-substituted pyrrole, with in addition an ester group or an acyl group at the 3-position, if a keto ster or a diketone respectively has been employed, and an ester group or an alkyl (aryl) group at the 5-position, according to the nature of the amino-ketone. 

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.) ... 

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. 

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 . 

Either or both of the R groups may be aryl. In general, dialkyl ketones and cyclic ketones react more rapidly than alkyl aryl ketones, and these more rapidly than diaryl ketones. The latter require sulfuric acid and do not react in concentrated HCl, which is strong enough for dialkyl ketones. Dialkyl and cyclic ketones react sufficiently faster than diaryl or aryl alkyl ketones or carboxylic acids or alcohols that these functions may be present in the same molecule without interference. Cyclic ketones give lactams. 

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. ... 

This section lists examples of the reaction of RH RR (R,R = alkyl or aryl). For the reaction C=CH -> C=C-R (R = alkyl or aryl), see Section 209 (Alkenes from Alkenes). For alkylations of ketones and esters, see Section 177 (Ketones from Ketones) and Section 113 (Esters from Esters). 

Scheme 4.23 Alkylations, arylation and vinylation of ketones with transA, 2-diami-nocyclopentane-based ligand.

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.

In 2000, Woodward et al. reported that LiGaH4, in combination with the S/ 0-chelate, 2-hydroxy-2 -mercapto-1,1 -binaphthyl (MTBH2), formed an active catalyst for the asymmetric reduction of prochiral ketones with catecholborane as the hydride source (Scheme 10.65). The enantioface differentiation was on the basis of the steric requirements of the ketone substituents. Aryl w-alkyl ketones were reduced in enantioselectivities of 90-93% ee, whereas alkyl methyl ketones e.g. i-Pr, Cy, t-Bu) gave lower enantioselectivities of 60-72% ee. 

Alkyltriphenylphosphonium halides are only weakly acidic, and a strong base must be used for deprotonation. Possibilities include organolithium reagents, the anion of dimethyl sulfoxide, and amide ion or substituted amide anions, such as LDA or NaHMDS. The ylides are not normally isolated, so the reaction is carried out either with the carbonyl compound present or with it added immediately after ylide formation. Ylides with nonpolar substituents, e.g., R = H, alkyl, aryl, are quite reactive toward both ketones and aldehydes. Ylides having an a-EWG substituent, such as alkoxycarbonyl or acyl, are less reactive and are called stabilized ylides. 

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. 

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