Synthesis and Properties of 1, 1‐Dihalogenocycloprop[b]Anthracenes

The synthesis of 1, 1‐difluoro‐1 H ‐cycloprop[ b ]anthracene ( 3 ) is described. The key step of the synthesis is the cycloaddition of 1,2‐dichloro‐3,3‐difluorocyclo‐propene ( 6 ) to 2,3‐dimethylidene‐1,2,3,4‐tetrahydronaphthalene ( 5 ). The 13 C‐NMR. spectrum of 3 is assigned on the grounds of C,F‐coupling constants, selective H‐decoupling and the resulting residual C,H‐coupling. The 1, 1‐dichloro derivative 4 was synthesized by the same route, but could not be isolated pure. Experiments for the reduction to 1 H ‐cycloprop[ b ]anthracene ( 2 ) and for the ionization of 3 or 4 to the cation 16 failed.