TEMPO-Mediated C–H Amination of Benzoxazoles with N‑Heterocycles

The
direct amination of benzoxazoles at C2 using N-heterocycles
as nitrogen sources has been developed for the first time. Several
kinds of inexpensive oxidants and also electricity were effective
for this transformation in the presence of 2,2,6,6-tetramethylpiperidine-N-oxyl. This metal-free and operationally simple reaction
can afford a variety of important C,N′-linked bis-heteocycles
in moderate to good yields under very mild reaction conditions. The
in situ generated oxoammonium salt was proved to be important for
this transformation.