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Organic Lab Reactions 176

Organic Lab Reactions 176 - 186 Another reagent fused zinc...

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MISCELLANEOUS METHODS AND REAGENTS 171 LXXXVIII gave the tetralone derivative LXXXIX in 99% yield. A modification of the phosphorus oxychloride method was used to cyclize CO 2 H CH CH 2 LXXXVI (R = H) LXXXVII (R - LXXXVIII (R = CH 3 O) LXXXIX (R =- < 7-2-methoxyphenylbutyric acid in 55% yield. syra-Tetrachloroethane was used as the solvent, and the mixture was boiled for two and one- half hours. 24 This was an improvement over the phosphorus pentoxide method which gave a yield of 16%. The excellent method for cyclizing o-benzylbenzoic acids to anthranol acetates, by heating the acid in- a mixture of acetic acid and anhydride with zinc chloride as a catalyst, 223 has been used also in the preparation of cyclic ketones of the tetralone type. In this way 7-3-acenaphthylbuty- ric acid has been cyclized in 78% yield; 224 7-2-phenanthrylbutyric acid *• and the 9,10-dihydro derivative 97 in 51% and 59% yields respectively; and a,/3-dimethyl-7-2-naphthylbutyric acid in 90% yield.
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Unformatted text preview: 186 Another reagent, fused zinc chloride, which has been more commonly used for the ring closure of o-benzylbenzoic acids, was applied to the cyclization of 7-3-pyrenylbutyric acid (Table IV, example 2). The reac-tion was carried out at 180°, and the yield was 16%. An interesting ring closure has been described in an attempt to effect an acylation of anisole with j3-phenylpropionic acid in the presence of chloroacetic anhydride. 73 Only intramolecular acylation occurred, giv-ing hydrindone-1; the yield after heating for forty-eight hours at 170° was 74%. 3,3-Diphenylhydrindone-l was similarly prepared in 67% yield. This further stresses the preference for intra- over inter-molecular acyla-tion. M »Fieser and Hershberg, J. Am. Chem. Soc., 59, 1028 (1937). !M Fieser and Hershberg, J. Am. Chem. Soc, 60, 1893 (1938)....
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