B(OH)-Mediated Reductive Ring-Opening of -Tosyl Aziridines by Nitroarenes: A Green and Regioselective Access to Vicinal Diamines.

The nucleophilic ring-opening of aziridine derivatives provides an important synthetic tool for the preparation of various β-functionalized amines. Amines as nucleophiles are employed to prepare synthetically useful 1,2-diamines in the presence of various catalysts or activators. Herein, the B(OH)-mediated reductive ring-opening transformation of -tosyl aziridines by nitroarenes was developed. This aqueous protocol employed nitroarenes as cheap and readily available amino sources and proceeds under external catalyst-free conditions. Control experiments and DFT calculations pointed to the reduction of nitroarenes to aryl amines via -aryl boramidic acid () and an S1-type ring-opening of -tosylaziridines by the resultant aryl amines with high regioselectivity.