Enantioselective Radical Construction of 5‑Membered Cyclic Sulfonamides by Metalloradical C–H Amination

Both arylsulfonyl and alkylsulfonyl
azides can be effectively activated
by the cobalt­(II) complexes of D2-symmetric
chiral amidoporphyrins for enantioselective radical 1,5-C–H
amination to stereoselectively construct 5-membered cyclic sulfonamides.
In addition to C–H bonds with varied electronic properties,
the Co­(II)-based metalloradical system features chemoselective amination
of allylic C–H bonds and is compatible with heteroaryl groups,
producing functionalized 5-membered chiral cyclic sulfonamides in
high yields with high enantioselectivities. The unique profile of
reactivity and selectivity of the Co­(II)-catalyzed C–H amination
is attributed to its underlying stepwise radical mechanism, which
is supported by several lines of experimental evidence.