POLYFLUOROCYCLOALKENES .8. STEREOISOMERIC 2H-PERFLUOROCYCLO-PENTYL AND -HEXYL METHYL ETHERS

The stereoisomeric 2H-octafluorocyclopentyl methyl ethers have been prepared by the lithium aluminium hydride reduction of the stereoisomeric 2-chloro-octafluorocyclopentyl methyl ethers obtained from the cobaltic fluoride fluorination of 2-chlorohexafluorocyclopentenyl methyl ether. Dehydrofluorination of both 2H-octafluorocyclopentyl methyl ethers with aqueous base was smooth and gave 1- and 3-methoxyheptafluorocyclopentene. 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-methoxynonafluorocyclohexene 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 agreement with the stereochemistry allocated. The trans-isomer was isolated also from the reaction of methanolic potassium hydroxide with decafluorocyclohexene in agreement with an addition - elimination process.