Aryl Methyl Sulfides as Substrates for Rhodium-Catalyzed Alkyne Carbothiolation: Arene Functionalization with Activating Group Recycling

A Rh­(I)-catalyzed method for the efficient functionalization
of
arenes is reported. Aryl methyl sulfides are combined with terminal
alkynes to deliver products of carbothiolation. The overall process
results in reincorporation of the original arene functional group,
a methyl sulfide, into the products as an alkenyl sulfide. The carbothiolation
process can be combined with an initial Rh­(I)-catalyzed alkene or
alkyne hydroacylation reaction in three-component cascade sequences.
The utility of the alkenyl sulfide products is also demonstrated in
simple carbo- and heterocycle-forming processes. We also provide mechanistic
evidence for the course of this new process.