Treatment of the bridged oxepine (±)‐1 with a large excess of powdered sodium methoxide in Et2O or with triphenylphosphonium methylide leads to the functionalized hydroazulenes (±)‐2 (69%) and (±)‐3 (81%). Regioselective and stereoselective cyclopropanation of (±)‐2 leads to the dibromocyclopropane derivative (±)‐4. Epoxidation gives the epoxides (±)‐5 and (±)‐6. The resolution of the hydro‐azulenone (±)‐2 is achieved by fractional crystallization of the quinine salt (–)‐8 of the corresponding mono acid (±)‐7. The absolute configuration of (+)‐7 is established by X‐ray analysis of the quinine salt (–)‐8.

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Irradiation of the dihydrooxepine monoester (+)‐4 gives the bridged bicyclobutane (+)‐5 in 77% yield. On the other hand, the corresponding diester 1 yields the cyclobutene 2. Possible explanations for this differing behaviour are discussed.