Identify the major product formed in the following reaction sequence:

Step-by-step solution

The given reactant contains two carbonyl groups: an ester ( - COOMe ) and an aldehyde ( - CHO ). The aldehyde group is more reactive towards nucleophilic addition than the ester group. Therefore, reaction with ethylene glycol ( HO -( CH ₂)₂- OH ) in the presence of an acid catalyst ( H ^+ ) selectively protects the aldehyde group by forming a cyclic acetal. The ester group remains unaffected. Intermediate formed: MeO - C (= O )- CH ₂- CH ( OCH ₂ CH ₂ O ) The protected intermediate is then treated with excess methyl