α, β-epoxy-artemisia ketone, 2 undergoes intramolecular cyclisation by OM-DM yielding the tetrahydrofuran derivatives 3–6, while on treatment with BF3,-etherate 2 cyclises to the cyclopentanones 8 and 9. The structure of all products has been elucidated by spectral methods. The mechanism of the cyclisation reaction is discussed briefly.
