Reaction scope. After investigating the reaction mechanism, the scope of this dearomative diamination was systematically investigated by using bifunctional reagent S8 as N-centered radical source under the optimized reaction conditions. As shown in Fig. , a range of representative electron-rich (hetero)arenes, such as indoles, benzofurans, benzothiophenes, phenanthrene and anthracene, smoothly underwent this protocol to form a variety of unsymmetrical diamines in moderate to good yields. Indoles with different N-protection groups, such as tert-butoxycarbonyl (Boc), methoxycarbonyl, pivaloyl, sulfonyl, or benzoyl, reacted with S8 in satisfactory yields (Fig. , 8, 19-22), and the structure of product 21 was further confirmed by X-ray crystallography. Then, various N-Boc protected indoles bearing either electron-donating or electron-withdrawing substituents on the aromatic ring or C3 position were well compatible with this reaction (Fig. , 23-40). Especially sensitive functional groups, such as chloro, bromo, acyloxy, ester, amide, cyano, formyl, and even boronic ester, were well-tolerated under the optimized conditions. To further test the compatibility of this method in more structurally complex contexts, several complicated indole-containing biologically active compounds such as Boc-protected Z-Trp-OMe and indoles embedded in gemfibrozil or dehydrocholic acid, were tested, affording the corresponding diamines in moderate yields (41-43). Unprotected indoles and N-alkyl or N-aryl indoles were, however, not suitable for this protocol. For instance, the reaction of 1H-indole H27 with S8 did not give any desired diamine product. The reactions of S8 with 1-methyl-1H-indole H28 or 3-methyl-1-phenyl-1H-indole H29