Photocatalytic deoxygenation of sulfoxides to sulfides over titanium(IV) oxide at room temperature without use of metal co-catalysts

• Photocatalytic deoxygenation of sulfoxides was examined over metal-free TiO2.
• Sulfoxides were successfully deoxygenated to corresponding sulfides with high yields.
• Formic acid and oxalic acid were appropriate as hole scavengers.
• The TiO2 photocatalyst could be repeatedly used without loss of activity.
• Phenyl vinyl sulfoxide was reduced to sulfide without hydrogenation of a CC bond.

Deoxygenation of sulfoxides was examined in acetonitrile suspensions of metal-free titanium(IV) oxide (TiO2) under irradiation of UV light at room temperature. Experimental results indicate that deoxygenation was induced by the TiO2 photocatalyst and that organic acids such as formic acid and oxalic acid are appropriate as hole scavengers in the photocatalytic reaction. Diphenyl sulfoxide was successfully deoxygenated to diphenyl sulfide with high yields, and the TiO2 photocatalyst could be repeatedly used for deoxygenation without loss of activity. The present photocatalytic method could be applied for deoxygenation of various sulfoxides to corresponding sulfides, and phenyl vinyl sulfoxide was chemoselectively reduced to phenyl vinyl sulfide without hydrogenation of a CC double bond.

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