<i>ipso</i>-Cyclization of unactivated biaryl ynones leading to thio-functionalized spirocyclic enones

Abstract

Ceric ammonium nitrate (CAN)-promoted oxidative <i>ipso</i>-cyclization of unactivated biaryl ynones with <i>S</i>-centered radicals (SCN/SCF₃) to access spiro[5,5]trienones has been established. This approach displayed excellent regioselectivity towards spirocyclization and tolerated a variety of functional groups. Dearomatization of hitherto unknown aryl/heteroaryl groups is also disclosed. DMSO is employed as a low-toxicity, inexpensive solvent as well as a source of oxygen.