Carbohydrates, among the most abundant biomolecules in nature, play crucial roles in the synthesis of bioactive molecules, drug development, and materials science. The selective oxidation of sugar hydroxyl groups represents a key strategy for synthesizing carbohydrate derivatives and achieving functional group interconversion. However, the inherent polyhydroxy structure and the similar reactivity of their hydroxyl groups present significant challenges for selective modification. Traditional methods rely on tedious protection/deprotection steps, leading to lengthy and inefficient synthetic routes. In recent years, the direct selective catalytic oxidation of unprotected sugars has emerged as a prominent research focus. This strategy significantly streamlines synthetic pathways, enhances atom economy, and reduces environmental impact. This review summarizes the progress in selective catalytic oxidation of unprotected or minimally protected sugars, providing a critical discussion of various catalytic systems employed in this field, including metal catalysis, photocatalysis, and electrocatalysis.

Key words: carbohydrate, selective oxidation, metal catalysis, photocatalysis, electrocatalysis