Ethyl 4-oxopentanoate is treated with exactly one equivalent of methyl magnesium bromide ( CH ₃ MgBr ) at a low temperature, followed by mild acidic hydrolysis. The major organic product formed is:

Step-by-step solution

The reactant, ethyl 4-oxopentanoate ( CH ₃- CO - CH ₂- CH ₂- COOCH ₂ CH ₃ ), contains two electrophilic functional groups: a ketone and an ester. Ketones are more reactive towards nucleophilic addition than esters because the ester carbonyl carbon is less electrophilic due to resonance donation from the adjacent oxygen atom. Since only one equivalent of methyl magnesium bromide ( CH ₃ MgBr ) is used, the Grignard reagent will selectively attack the more reactive ketone group. The ketone is converted into a tertiary