ipso -Cyclization of unactivated biaryl ynones leading to thio-functionalized spirocyclic enones.

Ceric ammonium nitrate (CAN)-promoted oxidative ipso -cyclization of unactivated biaryl ynones with S -centered radicals (SCN/SCF 3 ) 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.