Alkylation, acylation, and Beckmann rearrangement of oximes in the presence of an oxidation–reduction system

Abstract

The system triphenylphosphine–diethyl azodiformate (TPP–DAF) can interact with oximes in the presence of either carboxylic acids or alcohols. Reactions of benzophenone oxime with a variety of aromatic carboxylic acids lead to O-acyl derivatives which undergo spontaneous Beckmann rearrangement. This modification of the Beckmann rearrangement takes place under very mild (0 °C), aprotic (tetrahydrofuran), and weakly acidic conditions, affording NN-diacyl aromatic amines as final products. The reaction of benzophenone oxime with alcohols in the presence of TPP–DAF gives O-alkyl ethers of the oxime. A mechanism is proposed.