Does the Lossen rearrangement occur in the gas phase?

Abstract

Deprotonated hydroxamic acids and cognate systems undergo a number of rearrangement processes upon collisional activation. It is proposed that ions RCONOH undergo the Lossen rearrangement to form [(OCNR)HO^–], and that this reactive intermediate may decompose to form the ionic products HO^–, [(R – H)^–NCO], NCO^– and RNH^–. Alternatively, hydrogen transfer yields RCONHO^– which may undergo a three-centre reaction to produce RCO₂NH^–; this species may decompose to yield both RCO₂^– and [(R – H)CO₂]˙^–. Fragmentation processes have been investigated by both deuterium labelling and product ion studies.