Synthesis of (6,7-dichlorononafluoro-5,6,7,8-tetrahydronaphthalen-2-yl)acetic acid and its transformation into perfluorinated 2-methylnaphthalene and 6-methyl-1,4-dihydronaphthalene

Abstract

2,3-Dichlorodecafluorotetralin reacted with ethyl cyanoacetate to give ethyl 2-cyano-2-(6,7-dichlorononafluoro-5,6,7,8-tetrahydronaphthalen-2-yl)acetate which was hydrolyzed to (6,7-dichlorononafluoro-5,6,7,8-tetrahydronaphthalen-2-yl)acetic acid. The latter was treated with PCl₅ on heating to obtain 2,2-dichloro-(6,7-dichlorononafluoro-5,6,7,8-tetrahydronaphthalen-2-yl)acetyl chloride which was converted to 2,3-dichlorononafluoro-6-trifluoromethyl-1,2,3,4-tetrahydronaphthalene by the action of SbF₅. The reduction of 2,3-dichlorononafluoro-6-trifluoromethyl-1,2,3,4-tetrahydronaphthalene with zinc in 1,4-dioxane gave perfluoro-6-methyl-1,4-dihydronaphthalene, and in DMF, perfluoro-2-methylnaphthalene.