Ipso-Cyclization via a Dienone–Phenol Rearrangement of Alkynyloxy Cyclohexadienones for the Synthesis of Oxaspiro[4.5]trienones

Herein, we present a convenient method to access oxaspiro[4.5]trienone compounds from alkynyloxy cyclohexadienones. The reactions are catalyzed by Lewis/Bronsted acids, yielding the desired products in moderate to good yields under very mild reaction conditions. The process, which involves a dienone–phenol rearrangement, is characterized by its simplicity and the absence of any additional activators. The synthesis of the oxaspiro[4.5]trienone compounds is amenable to gram-scale reactions along with subsequent product transformations, making this approach practical and attractive.