Cyclohexanone is treated in sequence with (i) pyrrolidine, trace acid, water removed; (ii) $\mathrm{CH}{}_3\mathrm{COCl}$; (iii) $\mathrm{H}{}_3\mathrm{O}{}^{+}$. The final organic product is

The enamine carbon attacks the acyl chloride carbon (Stork acylation), giving an acylated iminium ion. Aqueous hydrolysis removes the amine to give the 1,3-diketone 2-acetylcyclohexan-1-one. O-acylation would give an ester, but C-acylation is the observed pathway.