| Abstrakt: |
Decachloro-4-allylidenecyclopentene (6) was synthesized by the reaction of pentachlorocyclopentadiene with hexachloropropene in the presence of anhydrous aluminium chloride. Hexachloro-2-allylidene-4-cyclopentene-1,3-dione (11), prepared from 6by treatment with coned nitric acid, cyclized to hexachloro-2,5-dihydrocyclopenta[b]pyran-5-one (14) on heating. In a solvent such as acetone and acetonitrile, 4rearranged to hexachloro-2,5-dihydrocyclopenta[b]pyran-2-one (18) at room temperature. The mechanism of this rearrangement is discussed. Hydrolysis of 14by 90% sulfuric acid afforded tetrachloro-2,5-dihydrocyclopenta[b]pyran-2,5-dione (15), which was obtained directly from 6by treatment with sulfuric acid. The reactions of 11with anhydrous methanol, and of 15with diazomethane were investigated. |
