The major product formed in the following reaction sequence is

Concept:

Wittig reaction:

• In the Wittig reaction, an aldehyde or a ketone is reacted with a triphenyl phosphonium ylide to yield an alkene along with triphenylphosphine oxide.
• An example is shown below:

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Claisen rearrangement:

• In a claisen rearrangement reaction, the allyl vinyl ether is converted into a gamma, delta-unsaturated carbonyl compound on heating or in presence of a Lewis acid.
• An example is shown below:

Cope rearrangement:

• The Cope rearrangement is a chemical reaction in organic chemistry that involves the [3,3]-sigmatropic rearrangement of 1,5-dienes on heating.
• An example is shown below:

Trans Esterification reaction:

• The transesterification reaction is the process of exchanging the organic functional group R¹ of an ester with the organic group R² of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst.

Explanation:

• The reaction pathway is shown below:

• From the above reaction, we can see that the phosphonium ylide reacts with the aldehyde to form the alkene.
• In the next step, the generated alkene undergoes a [3,3] Claisen rearrangement reaction followed by a [3,3] Cope rearrangement reaction.
• In the next step, the intermediate product undergoes an [1,5] H shift followed by a transesterification reaction to give the final product.

Conclusion:

Hence, the major product formed in the following reaction sequence is