Identify the product formed when $\text{D-fructose}$ is treated with dilute aqueous base followed by mild oxidation.

Solution

1. $\text{D-fructose}$ in dilute base undergoes enolization to form a common $\text{enediol}$ intermediate.
2. The $\text{enediol}$ can tautomerize to form $\text{D-glucose}$, $\text{D-fructose}$, or $\text{D-mannose}$.
3. This process is known as the $\text{Lobry de Bruyn-van Ekenstein}$ transformation.
4. Mild oxidation of this mixture would affect the aldoses present.
5. Hence the answer is (B).