Chemoselective reduction of nitrobenzenes having other reducible groups over titanium(IV) oxide photocatalyst under protection-, gas-, and metal-free conditions

m-Nitrostyrene was chemoselectively reduced to m-aminostyrene in an acetonitrile suspension containing a titanium(IV) oxide (TiO2) photocatalyst and a suitable hole scavenger at room temperature under atmospheric pressure without the use of a precious metal or reducing gas. Addition of a small amount of water to acetonitrile increased the reaction rate, and the highest rate was obtained. Moreover, applicability of the photocatalytic system was investigated using various nitro compounds having other reducible groups (chloro, bromo, carboxyl, and acetyl groups), and only the nitro group of these compounds was chemoselectively reduced, resulting in the formation of corresponding amino compounds with high yields.

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