Alkyl aryl

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. 

Oxonium salt formation. Shake up 0 5 ml. of ether with 1 ml. of cone. HCl and note that a clear solution is obtained owing to the formation of a water-soluble oxonium salt. Note that aromatic and aliphatic hydrocarbons do not behave in this way. In general diaryl ethers and alkyl aryl ethers are also insoluble in cone. HCl. 

Wurtz - Fittig reaction. The interaction of an aryl halide, alkyl hahde and sodium gives a reasonable yield of an alkyl aryl hydrocarbon, for example ... 

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

The last-named reaction provides an excellent method for the preparation of a-substituted glutaric acids the intermediate alkyl (aryl) -2-cyanoethyl-malonate is both hydrolysed and decarboxylated re ily by boiling with an excess of 48 per cent, hydrobromic acid solution. 

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.) ... 

Neutral oxygen-containing compounds in Solubility Groups I, II and V which either contain the CHjCO— group attached to H, alkyl, aryl, or ester H R... 

The highly regio- and diastereoselective addition of an alkyl and an arylthio group to an olefinic double bond ( carbosulfenylation ) is achieved with arenesulfenyl chlorides and alkyl-chloro-titanium(IV) species (Reetz reagent, from R2Zn/TiCU 5 1 M. T. Reetz, 1987, 1989), Use of the more bulky 2,4,6-triisopropylbenzenesulfenyl chloride improves the yield of the highly versatile alkyl aryl sulfide products. 

Alkyl, aryl, acyl. Used for colored pliotogra- 1036... 

Mono (H N-C-NHRi) or disubstituted (H N-C-NRiR i) selenoureas can be used. The group R, R( can be hydrogen, alkyl, aryl, acyl, or benzoyl. 

III. Alkyl, Aryl, Aralkyl aud Related Thiazole Derivatives... 

The reaction of a thioamide with a-halocarbonyl compounds has been applied extensively, and many thiazoles (10) with alkyl, aryl, aralkyl, or heteroaryl functional groups at the three 2-, 4-, or 5-positions have been reported (Scheme 6). 

The method has not been studied extensively and is restricted to the preparation of alkyl-, aryl-, or alkoxy-substituted thiazoles mostly in 2-, 5-, or 2,5-positions. Yields ranged from 45 to 80%. Sometimes this method gives good results when the usual Hantzsch s synthesis fails. There has been very little speculation about the mechanism of this reaction. 

The most general pathways to thiazoles bearing such groups as alkyl, aryl, aralkyl, and alkenyl, substituted or not by functional groups, are the cyclization reactions described in Chapter II. A certain number of indirect methods also exist, though only a few examples of each are given here. Others are discussed in the following chapters, with the more important references cited here. 

A large number of variously 2-, 4-, and 5-substituted thiazoles with alkyl, aryl, hydroxy, methylthio, mercapto, halo, and nitro groups have been analyzed by thin-layer chromatography on silica and alumina by the Stahl s technique (167, 170, 172). Among the many systems recommended for the elution of these compounds are the following ... 

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