Heterogeneous Meerwein‐Ponndorf‐Verley–type Reduction of Aromatic Aldehydes Having Other Reducible Functional Groups over a TiO2 Photocatalyst

Abstract

AbstractChemoselective reduction of benzaldehydes having other reducible functional groups without the use of a reducing agent such as metal hydrides is important because metal hydrides simultaneously produce a large amount of undesirable waste containing metal compounds. Here we report that a titanium(IV) oxide (TiO2) photocatalyst is effective for heterogeneous Meerwein‐Ponndorf‐Verley (MPV)‐type reduction of various benzaldehydes having reducible functional groups to corresponding benzyl alcohols at room temperature under a metal‐free condition. We also investigated the effects of physical properties of TiO2 samples on chemoselective reduction of p‐chlorobenzaldehyde (CBAD) to p‐chlorobenzyl alcohol (CBAO) and we observed a linear correlation between the amount of CBAD adsorbed and the rate of CBAO formation, suggesting that ability of TiO2 for CBAD adsorption is one of the key factors for effective MPV‐type reduction of CBAD to CBAO.