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Organic Lab Reactions 122

Organic Lab Reactions 122 - 9 Cyclization to form a five...

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THE SIZE OF THE RING 0 117 CO a H C 6 H 6 None of the isomeric hydrindone was obtained. Further substantiation was found in the conversion of benzylsuccinic acid (VII) into 3-car- boxytetralone-1 (VIII) as the only product of cyclization which could be isolated. 6 /3,7-Diphenylbutyric acid (IX), which has the structural possibility of cyclizing to 3-benzylhydrindone-l, gave only the product (X) of six-memberea ring closure. 7 In all cases the cyclizations were accomplished by the Friedel-Crafts method (p. 130), and the structures of the resulting ketones were proved. This preference regarding ring size is illustrated also by the cyclization of ;8,/3'-diphenyladipic acid to a chrysene derivative, 8 and by the formation of 3-carboxy-4-phenyl- tetralone-1 upon ring closure of diphenylmethylsuccinicracid.
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Unformatted text preview: 9 Cyclization to form a five- rather than a seven-membered ring is always realized provided that both modes of ring closure are subject to the same intrinsic cyclizing influence. This predilection for five-ring forma-tion was inferred from the observation 10 that benzosuberone (XII) was obtained repeatedly in yields of approximately 20% from S-phenylva-leric acid (XI), under the same conditions with which hydrindone-1 and also tetralone-1 were prepared in 70-80% yields. C0 2 H £12 CHj—CH 2 XI 7 v. Braun and Manz, Ann., 468, 258 (1929). 8 v. Braun and Irmisch, Ber., 64, 2461 (1931). •-Hewett, J. Chem. Soc, 1936, 596. 10 v. Braun and Rath, Ber., 60, 1182 (1927). XII...
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