Elemental Sulfur-Promoted Aerobic Dehydrogenative Aromatization of Cyclohexanones with Amines.

An elemental sulfur-promoted aerobic dehydrogenation system for the access to N,N'-dialkyl-o-phenylenediamines and N-substituted 2-naphthylamines is reported herein. Readily available cyclohexanones and amines (especially alkylamines) are transformed smoothly to target products. Aromatic amines can be achieved from all aliphatic reagents under aerobic metal-free reaction conditions. Control reactions show that the combinational use of elemental sulfur and molecular oxygen is exceptionally essential for this dehydrogenative aromatizaiton.