The free radical chemistry of the azoxy group

Abstract

The azoxy functional group, though relatively uncommon, is found in several natural products and in liquid crystalline compounds. Azoxyalkanes are generally very stable to heat and light and are not subject to attack by radicals. Intramolecular radical reactions, however, can lead to cyclic aminyl nitroxides and hydrazyls, which rearrange further or undergo fragmentation. The azoxy group greatly stabilizes an attached carbon-centered radical but the chemistry of the resulting α-azoxy radicals is not completely understood.

Photorearrangement of α-Azoxy Ketones and Triplet Sensitization of Azoxy Compounds

“…Despite its occurrence in a number of biologically active molecules, − the azoxy functional group has received less attention than its lower oxidation state analogue, the aliphatic azo group . The latter is a widely used source of free radicals, but as pointed out in a recent review, the radical chemistry of azoxy compounds is relatively sparse.…”

“… Although some aspects of azoxy group radical chemistry have been investigated, unhindered α-azoxy radicals remain poorly understood. Here we report the generation of α-azoxy radicals under mild conditions by irradiation of α-azoxy ketones 4a , b .…”