Facile One-Pot Transformation of Phenols intoo-Cyanophenols

The treatment of phenols with paraformaldehyde in the presence of MgCl2 and Et3N in THF at 80 °C, followed by reaction with molecular iodine and aq. ammonia at room temperature provided the corresponding o-cyanophenols in moderate to good yields. The present reaction is a one-pot transformation of phenols into o-cyanophenols using much less expensive reagents than are typically used; the reaction is free of both transition-metals and cyanide. The utility of this reaction was highlighted during our preparation of Febuxostat from p-bromophenol.