Thioarylative Radical Cyclization of Yne-Dienone

We
herein demonstrated a N-hydroxyphthalimide (NHPI)-mediated
chemo- and regioselective radical cyclization of yne-dienone with
thiols to construct 3-thioaryl bearing [6,6]-fused dihydrochromenone
derivatives. This transformation tolerates common functional groups
and has broad scope. The reaction proceeds via the attack of a thioaryl
radical to alkyne over the activated Michael acceptor. The TEMPO quenching
experiment suggests the involvement of a radical intermediate. Synthetic
versatility of 3-thioaryl­dihydro­chromenones is also showcased.