Palladium‐Catalyzed N3‐Directed C−H Halogenation of N9‐Arylpurines and Azapurines

A palladium‐catalyzed direct ortho‐halogenation of N9‐arylpurines was developed by using N‐halogenated succinimide (NBS/NCS/NIS) as the halogenation reagents. The current procedure offers a late‐stage strategy to generate N9‐(ortho‐haloaryl)purines in moderate to excellent yields. The protocol was applicable to the substrates with both electron‐rich and electron‐deficient substituents and only monohalogenated products were formed. Moreover, the purinyl N3‐atom was verified as the directing group to facilitate Pd‐catalyzed ortho‐C−H activation. A palladium‐catalyzed direct ortho‐halogenation of N9‐arylpurines was developed by using N‐halogenated succinimide (NBS/NCS/NIS) as the halogenation reagents. The current procedure offers a late‐stage strategy to generate N9‐(ortho‐haloaryl)purines with moderate to excellent yields. The protocol was available for the substrates with both electron‐rich and electron‐deficient substituents and only monohalogenated products were formed. Moreover, the purinyl N3‐atom was verified as the directing group to facilitate Pd‐catalyzed ortho‐C−H activation.