Selective Synthesis of Ketoxime Isomers Using Selenocompounds as a Catalyst

Oximes are important intermediates in organic synthesis and they have been used as building blocks in many organic transformations. They are used in the synthesis of N-substituted amides by Beckmann rearrangement or in the production of plastics, synthetic fibers, and pharmaceutical derivatives. With respect to their biological properties, oximes may act as bactericide, insecticide, herbicide, and fungicide, with the advantage of often having low toxicity. The traditional method to prepare oximes is the reaction of a carbonyl compound with an excess of hydroxylamine hydrochloride in the presence of a stoichiometric amount of base. However, both isomeric oximes (Z and E) are usually produced, except in the case of symmetrical ketones. The oxime stereochemistry is important for their physical and pharmacological properties, as well as their reactivity. Therefore, a method for controlling the stereochemistry of oximes is always required.

We described herein the use of diaryl diselenide and selenium dioxide as a catalyst in the double bond C-N isomerization of oximes. The reactions were performed using selenium dioxide and different species of diaryl diselenides with a range of ketoximes in green conditions. Several analysis using NMR equipment, such as ¹H-NMR, ¹³C-NMR, ⁷⁷Se-NMR, DEPT 135, COSY, HSQC, HMQC, HBQC and NOESY were performed to follow the reaction to discover intermediates and the interaction sites between the catalyst and the reactant.