The Neber Rearrangement

An early investigation of the Beckmann rearrangement led Neber to discover that treatment of O-sulfonyl ketoximes with base led to the formation of 2H-azirines. Neber's subsequent papers described in detail the full panoply of reactions, intermediates, and byproducts associated with the reaction, including α-amino ketones formed by acidic hydrolysis of the azirines. This chapter is devoted to the base-promoted rearrangement of oxime O-derivatives, commonly O-sulfonates, representing the original “Neber” rearrangement, and the corresponding reaction of N, N, N-trimethylhydrazonium iodides, the “modified Neber” rearrangement, discovered by Smith. Keywords: Beckmann Rearrangement; Ketoximes; 2H-Azirines; α-amino ketones; Neber Rearrangement