Migration and Cyclization Reactions

Double-bond Migration and Cyclization Reactions.—Linolenic acid (18 3 9cl2d5c) is converted by potassium hydroxide at 180°C or by sodium hydroxide at 220 °C, first to a conjugated trienoic acid, and then to a di-substituted cyclohexadiene (13—21 %), which is identified after aromatization with palladium-charcoal. A series of octadecatrienoic acids, when submitted to this reaction, gave the product(s) indicated in parentheses 9cl2cl5c (28 n = 3), 9/12/15/ (28 n =2,3, and 4), 9cll/13/ (28 n = 3, 4, and 5), 

Diene addition of ethylene to alkali-isomerized linoleic acid furnishes a Cgo acid containing a cyclohexene group. Attempts have been made to 

Methyl linoleate and methyl linolenate are isomerized to conjugated isomers with potassium t-butoxide at 60 °C and with tris(triphenylphosphine)-chlororhodium at 65 °C. Linoleyl alcohol and its methyl ether react with butyl-lithium and carbon dioxide to give mainly the 9-carboxy-Ai - and 13-carboxy-A -derivatives  

Reaction at C-13 seems to be slightly favoured. It is reported that the most probable explanation of the position discrimination is that the oxygen atom of the functional group helps, after coiling the chain, to solvate the lithium cation in the ion pair with the carbanion, and keeps it in such a position that most of the charge is located at C-13 .  

Ansell and Weedon have presented further reports on their studies of the alkali fusion of unsaturated acids, and of 0x0-, hydroxy-, epoxy-, and alkoxy-acids. The fission of 9(10)-hydroxy-10(9)-oxo-octadecanoic acid by alcoholic alkali at room temperature has been confirmed and shown to be an autoxida-tion reaction.  

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Methyl-3-phosphorylchroman-4-one 1106 is accessible via a tandem allyl-vinyl migration and cyclization reaction of the allylic phosphonate 1105 and ethyl salicylate (Equation 435) <2001SC2613>. 

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