Triplet Ketone Catalysis-Enabled Functionalization of Thioanisoles with Maleimides

Considering the importance of sulfur-containing organic
molecules
in various domains of chemistry, we report herein a protocol for the
catalytic diastereoselective synthesis of tricyclic heterocycles through
α-C(sp3)–H functionalization of thioanisoles
with maleimides enabled by triplet ketone catalysis. Mild reaction
conditions, an inexpensive photocatalyst, molecular oxygen as a terminal
oxidant, and compatibility with various functional groups are advantages
of the protocol. Preliminary mechanistic studies suggest the generation
of α-thioalkyl radicals and involvement of aerial oxygen in
our reaction conditions.