Cyclohexene is first treated with cold, dilute, alkaline $\mathrm{KMnO}{}_4$ and the product is then treated with $\mathrm{HIO}{}_4$. The final organic product is

Cold permanganate gives cis-cyclohexane-1,2-diol. Periodic acid cleaves the ring C-C bond between the two carbinol carbons and each end becomes an aldehyde group. The result is $\mathrm{OHC}-(\mathrm{CH}{}_2){}_4-\mathrm{CHO}$, hexanedial, the same product as ozonolysis with reductive work-up.