This reaction involves an intramolecular aldol reaction followed by a retro aldol-like reaction. The steps involved are as follows: 1. Deprotonation to form enolate ion 1; 2. Cyclization via an intramolecular aldol reaction to form tetrahedral intermediate 2; 3. Collapse of the tetrahedral intermediate and bond cleavage to form enolate ion 3; 4. Protonation to form the final product. Write out the reaction on a separate sheet of paper, and then draw the structure of enolate ion 3