New application of an old dye: Bay-annulated indigo (BAI) as an organic photocatalyst for the oxidation of organic sulfides.

• Efficient photocatalytic synthesis of sulfoxides from sulfides with good yields. • The method was achieved under visible light irradiation and ambient temperature conditions. • Gram-scale synthesis of sulfoxides was successfully conducted. • Photocatalytic oxidations of arylboronic acids and 2,3-dihydroquinazolinones were also investigated. Bay-annulated indigo (BAI), an old red dye first produced in 1914, which shows good performance as electron-accepting units in photovoltaic and semiconducting applications, was utilized as an organic photocatalyst for the first time. Under the irradiation of blue LEDs, organic sulfides can be selectively oxidized to corresponding sulfoxides with good to excellent yields. In addition, the photocatalytic oxidations of arylboronic acids and 2,3-dihydroquinazolinone derivatives were also investigated, indicating that it is a very promising organic photocatalyst for much more applications. [Display omitted] [ABSTRACT FROM AUTHOR]