Rongalite/iodine-mediated C(sp³)–H bond oximation and thiomethylation reaction of methyl ketones using copper nitrate as the [NO] reagent: synthesis of thiohydroximic acids

In this work, a highly efficient rongalite/iodine-mediated oxime formation reaction for the preparation of thiohydroximic acids from methyl ketones by employing copper nitrate as the [NO] reagent has been developed. Notably, copper nitrate participated as both a catalyst and the mild oximation reagent in the transformation. This reaction is highly efficient and facile, with a broad substrate scope, especially for fused ring skeleton substrates, heterocyclic skeleton substrates, and acetyl-substituted natural products. Mechanistic studies revealed that copper nitrate might be converted into a NO₂ radical or the NO₂ radical dimeric forms as an ion-pair equivalent to participate in the transformation.