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/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.

Automated summary

A CAN-promoted oxidative ipso-cyclization of unactivated biaryl ynones with S-centered radicals has been developed for the synthesis of spiro[5,5]trienones. The method exhibited excellent regioselectivity towards spirocyclization and tolerated various functional groups. Dearomatization of previously unknown aryl/heteroaryl groups was also achieved. DMSO was employed as a low-toxicity, inexpensive solvent and oxygen source.