The major product formed in the following reaction is

Concept:

Pd catalyzed cycloaddition reaction:

• Trimethylenemethane can be used to form a wide range of Five-membered rings such as cyclopentane, and cyclopentenes via  [3 + 2] cycloaddition reaction, catalyzed by palladium(0) complexes.
• The trimethylenemethane unit in these reactions is generally derived from the 2-[(trimethylsilyl)methyl]-2-propen-1-yl acetate, which is at the same time an allyl silane and an allylic acetate.
• Thus it is a weak nucleophile and an electrophile in the presence of palladium(0). Formation of the palladium π-allyl complex is followed by the removal of the trimethylsilyl group by nucleophilic attack of the resulting acetate ion.
• This produces a zwitterionic palladium complex that can undergo the cycloaddition reaction as follows:

Explanation:

• The reaction pathway is shown below:

• From the above reaction we can see that in the first step of the reaction, it forms a zwitterionic palladium complex.
• In the next step, the zwitterionic palladium complex undergoes a conjugate addition with the cyclopropane derivative followed by an attack of the resulting enolate on the π-allyl palladium unit to form a new five-membered ring having an Exo methylene group.

Conclusion:

Hence, the major product formed in the following reaction is