A facile and versatile method for
generating radicals from Csp3–H bonds under metal-free
and organic-peroxide-free
conditions was developed. By combining safe persulfate and low-toxic
quaternary ammonium salt, a wide variety of Csp3–H
compounds including ethers, (hetero)aromatic/aliphatic ketones, alkylbenzenes,
alkylheterocycles, cycloalkanes, and haloalkanes were selectively
activated to generate the corresponding C-centered radicals, which
could be further captured by N-arylacrylamides to
deliver the valuable functionalized oxindoles. Good functional group
tolerance was demonstrated. The useful polycarbonyl compound and esters
were also modified with the strategy. Moreover, the combination can
also be applied to the practical coupling between simple haloalkanes
and N-hydroxyphthalimide (NHPI).