Synthesis of Azoimidazolium Dyes with Nitrous Oxide

A new method for the synthesis of industrially important azoimidazolium dyes is presented. The procedure is based on a reagent which is rarely used in the context of synthetic organic chemistry: nitrous oxide (laughing gas). N2O is first coupled to N-heterocyclic carbenes. Subsequent reaction with aromatic compounds through an AlCl3-induced CH activation process provides azoimidazolium dyes in good yields.