Polyfluorocycloalkenes. Part VIII. The stereoisomeric 2H-perfluorocyclo-pentyl and -hexyl methyl ethers

Abstract

The stereoisomeric 2H-octafluorocyclopentyl methyl ethers have been prepared by the lithium aluminum hydride reduction of the stereoisometric 2-chloro-octafluorocyctopentyl methyl ethers obtained from the cobaltic fluoride fluorination of 2-chlorohexafluorocyctopentyl methyl ether. Dehydrofluorination of both 2H-octafluorocyclopentyl methyl ethers with aqueous base was smooth and gave 1 - and 3-methoxylheptalfluorocyclopentene. The stereoisomeric 2H-decafluorocyclohexyl methyl ethers were obtained from the cobaltic fluoride fluorination of 1H-6-methoxy-and 1H-2-methoxy-octafluorocyclohexene. The cis-2H-decafluorocyclohexyl methyl ether and aquous potassium hydroxide readily gave 1- and 3-methoxynonafluorocy flohexene in the ratio of 17 : 10, respectively, and the trans-isomer gave the same products in the ratio of 2 : 7, respectively, but much less readily, in agrement with the sterochemistry allocated. The trans-isomer was isolateds also from the reaction of methanolic potassium hydroxide with decaflurocyclohexene in agreement with an addition–elimination process.