Diboron Reagents in N‐N Bond Cleavage of Hydrazines, N‐Nitrosamines, and Azides: Reactivity and Mechanistic Insights

Diboron reagents are known for their ability to promote the deoxygenation of amine or pyridine oxides, nitroarenes, and nitrones through the formation of B‐O‐B bonds. In this study, we have investigated the potential of diboron reagents to induce N‐N bond cleavage in hydrazines, N‐nitrosamines and azides. Our findings show that the combination of B2nep2 as diboron source and KOMe as a Lewis base can effectively promote the N‐N cleavage of a wide variety of substrates. For hydrazines and nitrosamines, the presence of an aryl group is essential for the reaction to proceed, probably due to a better stabilization of the negative charge developed during N‐N bond cleavage. Both types of azides, aromatic and aliphatic, are easily reduced, and the resulting amines can be in situ converted into the corresponding amides by simple treatment with a carboxylic acid. Experimental and theoretical calculations suggest a non‐radical mechanism, with concerted B‐B and N‐N bond cleavage in the case of hydrazines and azides, and a stepwise mechanism in the case of N‐nitrosamines, where deoxygenation occurs as the first step, involving the formation of an N‐nitrene intermediate