Condition-Controlled O-Acylation and N–O Bond Reduction of Hydroximic Acids with Thioacetic Acid

Abstract

Condition-dependent transformations between hydroximic acids and thioacetic acid were achieved. Using NH4HCO3 in the ethanol solvent, efficient N–O bond cleavage of hydroxamic acids occurred to afford primary amides with high functional group compatibility. The reaction was switched to O-acylation when NEt3 and H2O were used as the base and solvent, respectively. These facile transformations could be scaled up to the gram level smoothly. Preliminary mechanistic studies suggested that the N–O bond cleavage involves a cascade process of acylation/reduction.

Copper-catalyzed synthesis of primary amides through reductive N–O cleavage of dioxazolones

“… 36 Moreover, a recent study showcased hydroxamic acids as amide sources, easily synthesized from carboxylic acids and hydroxylamine using 1,1′-carbonyldiimidazole, would be reduced to corresponding primary amides using thioacetic acid, NH 4 HCO 3 in ethanol. 37 In the past decade, dioxazolones, first invented by Beck and coworkers, 38 have been widely studied in the research area of catalytic C–H amidations using precious transition metals such as iridium and rhodium. 39–48 Despite the development of dioxazolones in transition metal catalysis, an alternative catalytic system is recognized to set the stage for a more convenient reaction regime that can be utilized under milder reaction conditions.…”