CBZ6 as a Recyclable Organic Photoreductant for Pinacol Coupling

A recyclable organic photoreductant (1 mol % CBZ6)-catalyzed reductive (pinacol) coupling of aldehydes, ketones, and imines has been developed. Irradiated by purple light (407 nm) using triethylamine as an electron donor, a variety of 1,2-diols and 1,2-diamines could be prepared. The oxidation potential of the excited state of CBZ6 is established as -1.92 V (vs saturated calomel electrode (SCE)). The relative high reductive potential enables the reductive coupling of carbonyl compounds and their derivatives. CBZ6 can be prepared in gram scale and is acid/base- or air-stable. It could be applied in large-scale photoreductive synthesis and recovered in high yield after the reaction.

Automated summary

The recyclable organic photoreductant CBZ6 catalyzes the reductive coupling of aldehydes, ketones, and imines under purple light irradiation, producing 1,2-diols and 1,2-diamines. With a high oxidation potential, CBZ6 is suitable for the reductive coupling of carbonyl compounds and their derivatives, making it a promising candidate for large-scale photoreductive synthesis.