AbstractThe reaction of 6,6‐dimethylfulvene (1) with small amounts of sodium cyclopentadienide (Na‐CPD) gives a mixture of oligomeric products, from which 1‐cyclopentadienyl‐1,3,3,‐trimethyltetrahydropentalene (7) was isolated with 67% yield. The structure of the main product7was proved by combination of spectrosopic methods as well as by NMR spectroscopy of its dianion. A reasonable reaction mechanism is presented and supported by isolation of other dimers9and12and trimers10as well as of side products11and13. The product distribution is severely influenced by increasing the amount of Na‐CPD (favouring oligomers of type11and13) as well as by addition of