MgCl₂-Catalyzed Chemoselective Reduction of Aldehydes, Ketones and Imines

Abstract

An operationally convenient Mg-catalyzed synthesis of alcohols by the reduction of aldehydes, ketones and α,β-unsaturated aldehydes/ketones is reported. It is a rare example of using mild and sustainable HBpin as a reductant for catalytic reduction of carbonyl compounds in the absence of acid or base as hydrolysis reagent. The reaction is up-scalable, and proceeds in high selectivity without the formation of boronate ester by-products, and tolerates sensitive functionalities such as iodine, bromide, chloride, fluoride, nitro, trifluoromethyl, aminomethyl, alkynyl, and amide. The MgCl2/HBpin combination has been also proved to be chemoselective for the C＝N reduction of imine analogs.

Photoredox/Bismuth Relay Catalysis Enabling Reductive Alkylation of Nitroarenes with Aldehydes

“…These results suggest a cascade reductive alkylation of nitroarenes with benzaldehydes by relay catalysis independently involving visible light-induced photoredox hydrogenation of nitroarenes to anilines [21] and bismuth-catalyzed reductive alkylation of amines with aldehydes. [22] Finally, we recorded the UV-vis absorption of each reaction components and their combinations in a solution of the same concentration as the real reaction mixture (Figure 5). The results reveal that the combination of PPh 3 and NaI features the same absorption with PPh 3 only in the UV (< 360 nm).…”