The present invention relates to a process for preparing at least one compound with Z−1 cycles and 7 to 16 carbon atoms with at least one aldehyde group, at least comprising the stages:(a1) oxidation of a composition (A), at least comprising a cyclic olefin with Z cycles and 7 to 16 carbon atoms and at least two C—C double bonds, by means of dinitrogen monoxide to give a composition (A1),(a2) separating off the at least one cyclic olefin with Z cycles and 7 to 16 carbon atoms with at least two C—C double bonds from the composition (A1) from stage (a1) in order to obtain a composition (A2),(b1) separating off the at least one cyclic compound with Z cycles and 7 to 16 carbon atoms with a keto group from the composition (A2) from step (a2), in order to obtain a composition (B1), comprising at least 50% by weight of the at least one compound with Z−1 cycles and 7 to 16 carbon atoms with at least one aldehyde group and at least two C—C double bonds,where Z may be 1, 2, 3 or 4.
