The cis-disubstituted cyclohexyl bromide shown is treated with $\mathrm{NaN}{}_3$ in DMF (clean $\mathrm{S}{}_{\mathrm{N}}2$ at the C-Br carbon). Which structure is the major product?

The compound is cis-1-bromo-3-methylcyclohexane (the pattern with [C@H] and [C@@H] is the meso, i.e. cis, one for 1,3-dimethyl; RDKit meso test True). Backside attack inverts C1, so the azide ends up trans to the methyl: trans-1-azido-3-methylcyclohexane. Retention, elimination (3-methylcyclohexene) and a cis product are not the $\mathrm{S}{}_{\mathrm{N}}2$ outcome.