Identify the major product of the following reaction sequence:

Step-by-step solution

The given starting material is ethyl 4-oxobutanoate, which contains both an aldehyde group and an ester group. Step (i): Reaction with ethylene glycol ( HOCH ₂ CH ₂ OH ) in the presence of an acid catalyst ( H ^+ ) and heat. Aldehydes are more reactive towards nucleophilic addition than esters. Therefore, the aldehyde group is selectively protected as a cyclic acetal (1,3-dioxolane), while the ester group remains unreacted. Step (ii): Reaction with lithium aluminum hydride ( LiAlH ₄ ) followed by mild acid workup.