The Stork enamine reaction and the intramolecular aldol reaction can be carried out in sequence to allow the synthesis of cyclohexenones. For example, reaction of the pyrrolidine enamine of cyclohexanone with 3-buten-2-one, followed by enamine hydrolysis and base treatment, yields the product indicated. The mechanism involves the following steps: Michael addition of the enamine to the unsaturated ketone yields carbanion 1; Proton transfer leads to enamine 2; Hydrolysis of the enamine leads to cyclohexanone 3; Deprotonation leads to carbanion 4; Intramolecular aldol addition leads to tetrahedral intermediate 5; Protonation leads to aldol addition product 6; Dehydration leads to the final product. Write out the reaction mechanism on a separate sheet of paper, and then draw the structure of tetrahedral intermediate 5.