“On-water” reduction of α-keto amide by Hantzsch ester: A chemoselective catalyst- and additive-free way to α-hydroxy amide

Cobalt-Catalyzed Chemoselective Reduction of N-Heteroaryl Ketones with N,N-Dimethylformamide as a Hydride Source

A method for chemoselective reduction of 2-pyridyl ketones and related N-heteroaryl compounds catalyzed by cobalt stearate using DMF as a hydride source is developed. The ketone substrate is activated by chelation with cobalt, which makes the present method highly chemoselective. A possible reaction mechanism is proposed on the basis of control experiments.

Rongalite-Mediated Transition Metal- and Hydride-Free Chemoselective Reduction of α-Keto Esters and α-Keto Amides

A transition metal- and hydride-free protocol has been developed for the chemoselective reduction of α-keto esters and α-keto amides using rongalite as a reducing agent. Here, rongalite acts as a hydride-free reducing agent via a radical mechanism. This protocol offers the synthesis of a wide range of α-hydroxy esters and α-hydroxy amides with 85-98% yields. This chemoselective method is compatible with other reducible functionalities such as halides, alkenes, amides, and nitriles. The use of inexpensive rongalite (ca. $0.03/1 g), mild reaction conditions, and gram-scale synthesis are some of the key features of this methodology. Also, cyclandelate, a vasodilator drug, has been synthesized in gram scale with 79% yield.