Phenol Umpolung: Nucleophilic Halogenation of Quinone Diazides to Give Halogenated Phenols

ABSTRACT In quinone diazides, the ortho or para diazo carbons are rendered electrophilic and therefore susceptible to reaction with simple nucleophiles such as halides in an umpolung of phenol reactivity. The reaction of a range of ortho ‐ and para ‐quinone diazides, readily prepared by diazotization of amino‐phenols or ‐naphthols, with halide anions (chloride, bromide, iodide) gives ortho ‐ or para ‐halogenated phenols in moderate to excellent yield. The effect of solvent, catalyst, nucleophile, and diazo substrate on the reaction was investigated, although attempts to extend the process to the nucleophilic addition of fluoride resulted in only trace quantities of fluorophenol being formed.