Reaction of 2, 2-bis (trifluoromethyl)-1, 1-dicyanoethylene (BTF; 1) with 6, 6-dimethylfulvene (2) affords the expected Diels-Alder cycloadduct, 7-(1-methylethylidene)-3, 3-bis (trifluoromethyl) bicyclo [2.2. 1] hept-5-ene-2, 2-dicarbonitrile (3), in good yield. The cycloadduct 3 is unstable and exists in equilibrium with the starting materials in less polar solvents. In more polar environment, the [4+ 2] adduct 3 either reverts to starting materials, ...
