Y-Arylbutyric acids

Procedure V. Ring Closure with Sulfuric Acid.198 For the conversion of Y-arylbutyric acids into cyclic ketones, the finely powdered acid (1 part) is added gradually with stirring to a mixture of concentrated sulfuric acid (3 volumes) and water (1 volume). After one hour s heating on the water bath the colored solution is cooled, diluted with water by pouring onto ice, and extracted with ether. The extract is washed with water, which removes traces of colored sulfonation product, then with dilute aqueous ammonia, and dried over anhydrous potassium carbonate the solvent is removed, the residue distilled under reduced pressure, and the distillate crystallized from a suitable solvent. 

CycHzation of y-arylbutyric acids. Eisenbraun et al.1 greatly prefer use of PPA to the acid chloride-AlCl3 procedure for cyclization of 4-(2,5-dimethylphenyl)-2-methyl-butyric acid (1) to 2,5,8-trimethyI-l-tetralone (2). 

The liquid reagent has high solvent power, particularly for oxygen-containing substances and for aromatic compounds. It is an effective dehydrating and condensing agent comparable to coned, sulfuric acid but less prone to permit secondary reactions such as enolization and aromatic substitution. Treatment with liquid HF at room temperature provides a simple and efficient method for the cyclization of /3-arylpropionic acids and y-arylbutyric acids to 1-indanones and 1-tetralones, as shown by the yields cited under the formulas of typical ketones. It is far superior... 

Haworth phenanthrene synthesis. Acylation of aromatic compounds with aliphatic dibasic acid anhydrides to (i-aroylpropionic acids, reduction of the carbonyl group according to Clemmensen or Wolff-Kishner procedures, cyclization of the y-arylbutyric acid with 85% sulfuric acid, and conversion of the cyclic ketone to polycyclic hydroaromatic and subsequently to aromatic compounds. 

Z-Arginine hydrochloride, 12, 4 Arsanilic acid, 16, 85 Arsonoacetic acid, 10,108 Arylarsonic acid, preparation, IS, 59 y-Arylbutyric esters, 18, 25 Arylsulfur chlorides, preparation, 15, 45... 

It has been known for some time190 that sulfuric add can be used as an agent for dehydrating y-arylbutyric and /3-arylpropionic acids to... 

Polycyclic Nuclei. In general, arylpropionic and arylbutyric acids in which the aryl group is a polycyclic aromatic nucleus cyclize readily. Cyclization into the a-position of the naphthalene nucleus, for example, takes place more ea( y than into the benzene ring. The ring closure of the substituted naphthylpropionic acids XXXIII and XXXV proceeded smoothly. 

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