Reduction of oximes and aliphatic nitro compounds to imines for further in situ reactions: a novel synthesis of pyrroles and pyrrolin-2-ones

Tributylphosphine–diphenyl disulphide is a self-drying reagent capable of reducing ketoximes and secondary aliphatic nitro compounds to the corresponding imines under strictly anhydrous conditions at room temperature. The imine may be hydrolysed to a ketone, acetylated to give an enamide, reduced to an amine, or captured by hydrogen cyanide to produce an α-amino nitrile. In the case of 1,4-nitro ketones or esters, intramolecular cyclisation leads to pyrroles or pyrrolin-2-ones. Aldoximes and primary nitro compounds are converted into nitriles by the reagent. Hydroxamic acids are reduced to the corresponding amides.