Selective Oxidation of Sufur‐Containing Flavones: Synthesis of Sulfoxide/Sulfone‐Flavonoids

A transition‐metal‐free protocol is proposed for the selective oxidation of flavones, providing various sulfoxide/sulfone‐flavonoids in excellent yields. This strategy features excellent selectivities, high yields and broad substrate scope. The combination of oxone (2KHSO 5 ⋅ KHSO 4 ⋅ K 2 SO 4 ) as the sole oxidant and NaHCO 3 /Na 2 CO 3 as the buffer play an important role in the process, in which the amounts of oxone and reaction temperatures are the key to the outstanding selectivities and high efficiency of the reaction. It should be noteworthy that a class of novel sulfone‐flavonols is also synthesized through triple oxidation. Moreover, the glycosylation of sulfone‐flavonols has been realized.