The bifunctional compound shown is treated with one equivalent of methanol and pyridine at 0 degrees C. Which structure is the major product?

The acid chloride is a far more reactive acyl derivative than the primary amide. Methanol attacks the acid chloride carbonyl and chloride leaves, giving the methyl ester while the amide is unchanged. The product is methyl 4-amino-4-oxobutanoate (a monoamide monoester); the amide group is a poor electrophile because of the nitrogen lone pair resonance and the poor NH2 leaving group.