dichloromethane in the presence of added carbonyl compounds (3) resulted almost exclusively in monoozonolysis reactions to give the corresponding unsaturated cross-ozonides 8 and/or 10 as the major products. In contrast, ozonolysis of the nonconjugated olefins 1,5-cyclooctadiene (6a) and 1,5-dimethyl-1,5-cyclooctadiene (6b) under similar conditions afforded both unsaturated cross-ozonides (11 and 17, respectively)