The major product formed in the following reaction is

Concept:

• In an aldol reaction, the enolate of an aldehyde or a ketone reacts at the α-carbon atom with the carbonyl of another molecule under basic or acidic conditions to obtain a β-hydroxy carbonyl compound.
• The mechanism of the aldol reaction is shown below:

• In intramolecular aldol reaction, the enolate donor and the electrophilic acceptor of an aldol reaction are contained in the same molecule such as dialdehydes, keto aldehydes, or diketones.

Explanation:

• The reaction pathway is shown below:

• From the above reaction we see that in the first step, the tri-keto compound undergoes the intramolecular aldol reaction in presence of Sodium ethoxide (NaOEt).
• The resonance-stabilized enolate ion undergoes an intramolecular aldol reaction to give the β-hydroxy carbonyl compound.
• In the final step, the β-hydroxy carbonyl compound undergoes dehydration to give the final product. 

Conclusion:

Hence, the major product formed in the following reaction is 

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