1-Methylcyclohexene is ozonised and then treated with $\mathrm{H}{}_2\mathrm{O}{}_2$ (oxidative work-up). The product is

Cleavage of the ring double bond gives a ketone at the methylated carbon, $-\mathrm{C}(=\mathrm{O})\mathrm{CH}{}_3$, and an aldehyde at the other carbon. Oxidative work-up converts only the aldehyde to $\mathrm{COOH}$. The product is $\mathrm{HOOC}-(\mathrm{CH}{}_2){}_4-\mathrm{CO}-\mathrm{CH}{}_3$, 6-oxoheptanoic acid.