The cyclic ketone shown is stirred with pyrrolidine and a catalytic amount of acid, with removal of water. Which structure is the isolable product?

Cyclopentanone and the secondary amine pyrrolidine form a carbinolamine, which loses water to give an iminium ion. This ion has no N-H to lose, so it loses an alpha proton to give the neutral enamine, 1-(cyclopent-1-enyl)pyrrolidine. The iminium and carbinolamine are intermediates, and the saturated amine would require a reducing agent.