A Direct BrOnsted Acid-Catalyzed Azidation of Benzhydrols and Carbohydrates

Benzhydryl alcohols were converted into their corresponding diarylazidomethane analogues using azidotrimethylsilane (TMSN3) in the presence of a catalytic amount of a BrOnsted acid HBF4OEt2. The azidation reactions proceeded in high yields and demonstrated excellent functional group tolerance to electron-donating and electron-withdrawing substituents. In addition, a range of unprotected functional groups including amine, amide, aldehyde and alcohol were well-tolerated. Furthermore, this methodology was successfully applied to carbohydrates for the preparation of the corresponding azide derivatives.