The enamine shown is alkylated with methyl iodide and the product is then hydrolysed with dilute aqueous acid (Stork enamine sequence). Which structure is the final organic carbonyl product?

The enamine of cyclohexanone is nucleophilic at the beta (ring) carbon, which attacks methyl iodide to give a C-methylated iminium salt. Aqueous acid hydrolyses the iminium ion to the ketone and piperidine, giving 2-methylcyclohexanone as the monoalkylated product. Hydrolysis without alkylation would give only cyclohexanone.