1,1-Bis(trifluoromethyl)butadiene-1,3—A new fluorinated building block

Although 1,1-bis(trifluoromethyl)butadiene-1,3 (1) reacts with dimethylamine with selective formation of 1,4-adduct [trans-(CF3)2CHCHCHCH2N(CH3)2], halogenation of 1 proceeds with predominant formation (>92%) of 1,2-adducts (CF3)2CCHCHXCH2X (X = Cl or Br). Electrophilic conjugated addition of “ClF” or “BrF” to 1 proceeds exclusively with the formation of 1,2-adducts (CF3)2CCHCHFCH2X (major) and (CF3)2CCHCHXCH2F (X = Cl or Br). Difluorocarbene adds selectively to CHCH2 moiety of 1 forming thermally stable vinylcyclopropane. In Diels-Alder reaction with linear or cyclic dienes (butadienes, cyclopentadiene, cyclohexadiene-1,3) and quadricyclane compound 1 behaves as dienophile providing for the reaction electron-deficient CHCH2 bond. The relative rate of cycloaddition of 1 and other fluoroolefins to quadricyclane, measured by high temperature NMR, indicates that (CF3)2CCH acts as very strong electron-withdrawing substituent. Synthetic utility of products based on 1 was also demonstrated.

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