Dedicated to Professor Koichi Narasaka with Gratitude on the occasion of his 77th Birthday (Kiju).The first efficient diazo-transfer reaction of phenols is described. o-Quinone diazides (diazoquinones) were prepared from phenols in high yields by the diazo-transfer reaction using 2-azido-1,3-bis(2,6-diisopropylphenyl)imidazolium hexafluorophosphate (IPrAP, 2-PF 6 ), which is a safe and stable crystalline. The reaction efficiently proceeded in methanol in the presence of a base. Phenols substituted with electron-donating groups reacted more smoothly than those having electron withdrawing groups. Reactive phenols were diazotized by IPrAP with i Pr 2 NH as a base, and low reactive phenols were diazotized with N,Ndimethyl-4-aminopyridine (DMAP). Furthermore, the formed diazoquinones reacted with sodium azide in 2-methoxyethanol and afforded the corresponding azidophenol in high yields.