Insights Into the Carbohydrates Synthon in Brønsted Acid Catalyzed <i>N</i> ‐Formylation

Catalytic processes utilizing air as an environmentally benign oxidizing agent and acid catalysts offer significant advantages in converting renewable or sustainable carbohydrate feedstocks into high‐value chemical compounds. Herein, a remarkably efficient and innovative Brønsted acid‐catalyzed system has been developed, utilizing air as the sole oxidant, completely devoid of transition metals or costly oxidizing reagents. The system enables oxidative C−C/H activation and N ‐formamidation of amine and dextrose with notable efficiency synthesis of a diverse array of formamides while achieving impressive turnover numbers (TON = 91,455). Labeling studies have demonstrated that the carbon atom in the aldehyde group originates from the C1 position of dextrose, the hydrogen atoms are derived from the C−H bonds position within the dextrose skeleton, the H atom in the amide (NH) group originates from a hydroxyl group of dextrose, and the oxygen atom is derived from atmospheric O 2 . Mechanistic investigations have revealed that acidic conditions significantly promote the oxidation of dextrose by molecular oxygen.