SYNTHESIS OF 7,7-DIMETHYLNORBORNADIENE

Two short syntheses of 7, 7-dimethylnorbornadiene starting from 4, 4-dimethylcyclopent-2-enone are described. The latter in its dienol form reacts with maleic anhydride to give the [4 + 2] adduct. Successive hydrolysis and oxidative decarboxylation gives 7, 7-dimethylnorbom-2-en-5-one. The corresponding tosylhydrazone on treatment with lithium diisopropylamide gives 7, 7-dimethylnorbornadiene. Alternatively, the cyclopentenone is reduced to the allylic alcohol, and then dehydrated to 5, 5-dimethylcvclopentadiene. The [4 + 2] adduct of the latter and achloroacrylonitrile, on hydrolysis, affords the norbornenone, which is converted as before to 7, 7-dimethylnorbornadiene. © 1979, American Chemical Society. All rights reserved.