Organic Chemistry
The enolate ion formed from nonane-3,8-dione is not nucleophilic enough to effectively attack the second carbonyl carbon.
The intermediates formed after ring-closing are not resonance stabilized resulting in a high-energy requirement for the reaction to occur.
The reaction ends in the formation of the aldol product and dehydration to form the α,β-unsaturated product does not occur.
The reaction is not favored because the nucleophile and the electrophile are farther apart and the probability of an intramolecular attack is decreased.