Organic Lab Reactions 180

Organic Lab Reactions 180 - equal quantities of...

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INFLUENCE OF METHOD ON DIRECTION OF CYCLIZATION 175 of a mixture of the a- and /3-substitution products. 286 That a change in reaction temperature may influence the proportion of isomers was shown in the succinoylation of acenaphthene. 90 Changing the method of acetylating acenaphthene from the Friedel-Crafts to the hydrogen fluo- ride technique was found to make possible the preparation of a new acetoacenaphthene in yields which can be accounted for only by a definite change in the proportion of isomers. 16 - 237 In the present problem of intramolecular acylation the conditions which have been most effective in altering the direction of ring closure have been those which involve different methods of cyclization. The case of 7-5,6,7,8-tetrahydro-2-naphthylbutyric" acid (XC) affords an example of the possibility of controlling, at least partially, the direction of ring closure by using different methods. When the free acid chloride (CH,),CX)IH xo xci xcn was heated under reduced pressure, an 83% yield of a mixture of about
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Unformatted text preview: equal quantities of l-keto-l,2,3,4,5,6,7,8-octahydroanthracene (XCI) and 4-keto-l,2,3,4,5,6,7,'8-octahydrophenanthrene (XCII) was ob-tained. 69 On the other hand, when the acid (XC) was cyclized with warm concentrated sulfuric acid, a homogeneous product, which proved to be the ketooctahydroanthracene XCI, resulted in 75% yield. 16 Another instance of selective ring closure was reported 98 in the cyclization of Y-5-methoxy-l-naphthylbutyric acid (XCIV). The (CHs) 8 CO 2 H " 0 SnCl + SomeXCIII OCHs xcv Friedel-Crafts reaction with aluminum chloride in sywt-tetrachloro-ethane gave 7-keto-4-methoxyhomoperinaphthane (XCIII) in 41% yield. Heating the free acid with stannic chloride, however, produced l-keto-8-methoxy-l,2,3,4-tetrahydrophenanthrene (XCV) in 40% yield S8 «Eivkin, J. Qen. Chem. U.S.S.R., 6, 277 (1935). JS7 Fieser and Kilmer, J. Am. Chem. Soc, 62, 1354 (1940)....
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